ORCID Profile
0000-0001-5434-3816
Current Organisation
University of Tasmania
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Horticultural Production | Plant Biology | Horticultural Crop Protection (Pests, Diseases and Weeds) | Plant Pathology | Food Packaging, Preservation and Safety | Food Processing | Plant Pathology | Analytical Spectrometry | Analytical Spectrometry | Plant Improvement (Selection, Breeding And Genetic Engineering) | Higher Education | Plant Growth And Development | Food Sciences | Plant Protection (Pests, Diseases And Weeds) |
ANZSRC Socio-Economic Objective (SEO)
Horticultural crops not elsewhere classified | Plant Extract Crops (e.g. Pyrethrum, Jojoba) | Vegetables | Plant Production and Plant Primary Products not elsewhere classified | Vegetables | Processed Food Products and Beverages (excl. Dairy Products) not elsewhere classified | Food Safety
Related Links
Publications
Spatiotemporal Analysis of Epiphytotics of Downy Mildew of Oilseed Poppy in Tasmania, Australia
Publisher: Scientific Societies
Date: 06-2003
DOI: 10.1094/PHYTO.2003.93.6.752
Abstract: Downy mildew, caused by Peronospora arborescens, has become the major disease affecting oilseed poppy (Papaver somniferum) since its first record in Tasmania in 1996. Two field trials conducted in 2000 and 2001 studied the progression and spatial distribution of downy mildew epiphytotics. The logistic and exponential models best described the progression of disease incidence and severity, respectively. Incidence and severity increased rapidly following canopy closure. In 2001, incidence increased from 0.16%, prior to canopy closure, to 100% at late flowering (40 days). Spatial analyses of epiphytotics were conducted by fitting the beta-binomial and binomial distributions, median runs analysis, and the spatial analysis by distance indices. All analyses demonstrated that the distribution of incidence and severity was strongly spatially aggregated from canopy closure until at least late flowering. These results suggest that secondary spread from a few primary infections is the major factor in epiphytotics.
Relationship of resistance to common scab disease and tolerance to thaxtomin A toxicity within potato cultivars
Publisher: Springer Science and Business Media LLC
Date: 06-09-2019
Spatiotemporal Description of Epidemics Caused by Phoma ligulicola in Tasmanian Pyrethrum Fields
Publisher: Scientific Societies
Date: 06-2005
Abstract: Spatial and temporal patterns of foliar disease caused by Phoma ligulicola were quantified in naturally occurring epidemics in Tasmanian pyrethrum fields. Disease assessments (defoliation incidence, defoliation severity, incidence of stems with ray blight, and incidence of flowers with ray blight) were performed four times each year in 2002 and 2003. Spatial analyses based on distribution fitting, runs analysis, and spatial analysis by distance indices (SADIE) demonstrated aggregation in fields approaching their first harvest for all assessment times between September and December. In second-year harvest fields, however, the incidence of stems with ray blight was random for the first and last s lings, but aggregated between these times. Spatiotemporal analyses were conducted between the same disease intensity measures at subsequent assessment times with the association function of SADIE. In first-year harvest fields, the presence of steep spatial gradients was suggested, most likely from dispersal of conidia from foci within the field. The importance of exogenous inoculum sources, such as wind-dispersed ascospores, was suggested by the absence of significant association between defoliation intensity (incidence and severity) and incidence of stems with ray blight in second-year harvest fields. The logistic model provided the best temporal fit to the increase in defoliation severity in each of six first-year harvest fields in 2003. The logistic model also provided the best fit for the incidence of stems with ray blight and the incidence of flowers with ray blight in four of six and three of six fields, respectively, whereas the Gompertz model provided the best fit in the remaining fields. Fungicides applied prior to mid-October (early spring) significantly reduced the area under disease progress curve (P 0.001) for defoliation severity, the incidence of stems with ray blight, and the incidence of flowers with ray blight for epidemics at all field locations. This study provides information concerning the epidemiology of foliar disease and ray blight epidemics in pyrethrum and offers insight on how to best manage these diseases.
Susceptibility of pyrethrum and opium poppy to tomato spotted wilt tospovirus infection
Publisher: Springer Science and Business Media LLC
Date: 1999
DOI: 10.1071/AP99052
Determining specific window period for common scab disease infection in potato tubers
Publisher: Nepal Journals Online (JOL)
Date: 08-05-2017
Abstract: A series of experiments was conducted under glasshouse and hydroponic conditions to determine the specific window period for common scab disease infection in potato tubers. The study was performed in a glasshouse system where separate tubers from the root zone were inoculated at different intervals during plant growth along with a novel hydroponic system to inoculate in idual tubers at specific times of development growth allowing non-destructive observations of common scab symptoms developing. The window of tuber susceptibility to common scab disease infection was shown to vary with the season or conditions under which the plants were grown. Different internodes on tubers were found susceptible to infection at different times during tuber development. Basal internodes, which are the first sections of the tuber to expand, were susceptible to infection in the beginning of tuber development, whereas apical internodes only became susceptible later in tuber growth when the basal internodes were no longer susceptible.Journal of Nepal Agricultural Research Council Vol.3 2017: 19-26
Potato Tuber Greening Risk is Associated with Tuber Nitrogen Content
Publisher: Springer Science and Business Media LLC
Date: 18-06-2020
Assessing sequence diversity of groundnut rosette disease agents and the distribution of Groundnut rosette assistor virus in major groundnut-producing regions of Ghana
Publisher: Springer Science and Business Media LLC
Date: 03-2017
Evaluation of resistance to potato leafroll virus in selected potato cultivars under field conditions
Publisher: CSIRO Publishing
Date: 1993
DOI: 10.1071/EA9930083
Abstract: To test the resistance of potato cultivars to potato leafroll luteovirus (PLRV) in the field, small plots each containing 3 rows of 3 plants of the same cultivar were planted next to a row of infector plants. Harvested tubers were tested for PLRV infection by enzyme-linked immunosorbent assay. Most of the PLRV spread (85%) was sequential rather than random (i.e. related to distance between test and infector plants). Twenty-six potato cultivars were screened for resistance to PLRV in 6 trials during 3 years at 3 locations. Summer, autumn, or winter plantings were made. There were significant differences between cultivars in the degree of PLRV resistance and susceptibility, independent of location, season, or year. Of the cultivars included in at least 2 trials each, the most resistant were Delcora, Omega, Spunta, and Whitu. Most susceptible were Cadima, Denali, Elliot, Renova, Russet Burbank, and Tor. Contrary to earlier reports, Spunta was resistant, while Delaware was relatively susceptible. Four Australian-bred cultivars (Cadima, Elliot, Geographe, and Tor) that were tested for the first time had little or no resistance, and 2 (Bremer and Toolangi Delight) were intermediate. The incomplete (quantitative) nature of resistance to initial infection with PLRV by viruliferous aphids was demonstrated in a seventh field trial where aphids were more abundant and all plants became infected, including resistant cultivars Delcora and Omega.
First Report of Cucumber Mosaic Cucumovirus on Wasabi in Australia
Publisher: Scientific Societies
Date: 05-1998
DOI: 10.1094/PDIS.1998.82.5.590A
Abstract: Wasabi (Wasabia japonica (Miquel) Matsum.), a native perennial of Japan and Shakhalin Island used to produce a condiment for Japanese dishes, is under commercial development in Tasmania, Australia. Plants propagated within shade houses showed systemic necrotic flecks and veinal necrosis in leaves and sunken necrotic stem lesions similar to those, reported in Japan (1), caused by cucumber mosaic cucumovirus (CMV). Necrosis progressed rapidly, resulting in death of plants transferred to or mechanically inoculated in a glasshouse (15 to 30°C) under full light. Disease progression in plants maintained in shade houses (5 to 20°C) was slower and symptoms less severe. Presence of CMV in symptomatic plants was confirmed by enzyme-linked immunosorbent assay (ELISA), using antiserum from Agdia (Elkhart, IN), and by sap transmission tests to healthy wasabi and Chenopodium quinoa plants. Incidence of CMV among plants in the shade houses was estimated at 10%. A survey of a commercial planting of 400 to 500 plants in November 1997, using ELISA, showed an incidence of 2.6% CMV-infected plants. They were concentrated at the field margins, suggesting that the inoculum originated from external sources rather than from transplants. This pathogen could have significant impact on the longevity and production of this crop in Australia. Reference: (1) S. Adachi. 1987. Wasabi cultivation. Shizuoka Pref. Agric. Exp. Sta. Pub., Shizuoka, Japan.
Confirmation of ray blight disease of pyrethrum in Australia
Publisher: Springer Science and Business Media LLC
Date: 1998
DOI: 10.1071/AP98004
Transmission of Hop Latent and Hop Mosaic Carlaviruses by Macrosiphum euphorbiae and Myzus persicae
Publisher: Wiley
Date: 13-11-2006
DOI: 10.1111/J.1439-0434.2006.01164.X
Abstract: Macrosiphum euphorbiae and Myzus persicae , polyphagous aphid species commonly found within hop gardens in Australia, were confirmed as vectors of hop latent virus (HpLV) and hop mosaic virus in glasshouse trials. Both vectors transmitted either virus with equivalent efficiency. This is the first record of HpLV transmission by an aphid other than Phorodon humuli . Furthermore, aphids feeding on single infected plants, sequentially on plants infected with one virus and then the other or on co‐infected source plants did not influence transmission efficiency of either virus, nor was the frequency of co‐transmission affected by the order of virus acquisition. The role of these vectors in carlavirus epidemics in Australian hop gardens is discussed.
Foliar treatment of 2,4-dichlorophenoxyacetic acid for control of common scab in potato have beneficial effects on powdery scab control
Publisher: Hindawi Limited
Date: 2014
DOI: 10.1155/2014/947167
Abstract: Prior studies have shown that applications of the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) to the foliage of potato plants can reduce common scab. Here field and glasshouse trials suggest that 2,4-D foliar treatments may also reduce the biologically distinct tuber disease, powdery scab. Significant correlations between suppression of common and powdery scab from the field trials suggested an interaction between the two diseases or possible additional broad spectrum mechanisms of enhanced defence against pathogen invasion provided by 2,4-D treatment.
Virus content of seed potato stocks produced in a unique seed potato production scheme
Publisher: Wiley
Date: 02-1990
Biological properties of potato virus X in potato: effects of mixed infection with potato virus S and resistance phenotypes in cultivars from three continents
Publisher: Scientific Societies
Date: 2012
Abstract: Interactions between Potato virus X (PVX) and Potato virus S (PVS) were studied in potato plants, and isolates of PVX were inoculated to potato cultivars from four continents to identify occurrence of PVX resistance genes. Mixed infection with PVX and PVS increased the titer of PVS and enhanced expression of foliar symptoms in primarily and secondarily infected plants of ‘Royal Blue’. PVX isolates belonging to strain groups 1 and 3 (WA1+3) or 3 (XK3 and TAS3) were sap and graft inoculated (1 to 3 isolates each) to 38 cultivars and one breeding line. Presence of extreme PVX resistance gene Rx was identified in four Australian (‘Auski’, ‘Billabong’, ‘Flame’, and ‘Ruby Lou’) and two European (‘Mondial’ and ‘Rodeo’) cultivars, and in a clone of North American ‘Atlantic’. PVX hypersensitivity gene Nx was identified for the first time in two Australian (‘Bliss’ and ‘MacRusset’), four European (‘Almera’, ‘Harmony’, ‘Maxine’, and ‘Nadine’), and one North American (‘Ranger Russet’) cultivars, and in Australian breeding line 98-10713. PVX hypersensitivity gene Nb was identified for the first time in one Australian (‘White Star’), five European (‘Innovator’, ‘Kestrel’, ‘Kipfler’, ‘Laurine’, and ‘Royal Blue’), and one North American (‘Shepody’) cultivars. Probable ancestral sources of the resistance genes found in different cultivars were identified. Thus, although PVX resistance genes often occur in parents used in crosses, knowledge of their occurrence in parents and cultivars is often lacking. On sap inoculation, systemic hypersensitive phenotypes that caused shoot death often developed in cultivars with Nx but not necessarily in all shoots. This phenotype caused severe necrotic symptoms in infected tubers. In some instances, passage through cultivars with Nb separated strain group 3 from mixed isolate WA1+3.
Variability within Clones of Potato cv. Russet Burbank to Infection and Severity of Common Scab Disease of Potato
Publisher: Wiley
Date: 03-10-2001
Genomic Characterisation of an Isolate of Brassica Yellows Virus Associated with Brassica Weed in Tasmania
Publisher: MDPI AG
Date: 25-03-2022
Abstract: Brassica yellows virus (BrYV), a tentative species in the genus Polerovirus, of the Solemoviridae family, is a phloem-restricted and aphid-transmitted virus with at least three genotypes (A, B, and C). It has been found across mainland China, South Korea, and Japan. BrYV was previously undescribed in Tasmania, and its genetic variability in the state remains unknown. Here, we describe a near-complete genome sequence of BrYV (genotype A) isolated from Raphanus raphanistrum in Tasmania using next-generation sequencing and sanger sequencing of RT-PCR products. BrYV-Tas (GenBank Accession no. OM469309) possesses a genome of 5516 nucleotides (nt) and shares higher sequence identity (about 90%) with other BrYV isolates. Phylogenetic analyses showed variability in the clustering patterns of the in idual genes of BrYV-Tas. Recombination analysis revealed beginning and ending breakpoints at nucleotide positions 1922 to 5234 nt, with the BrYV isolate LC428359 and BrYV isolate KY310572 identified as major and minor parents, respectively. Results of the evolutionary analysis showed that the majority of the codons for each gene are evolving under purifying selection, though a few codons were also detected to have positive selection pressure. Taken together, our findings will facilitate an understanding of the evolutionary dynamics and genetic ersity of BrYV.
Germinate to exterminate: chemical stimulation of Spongospora subterranea resting spore germination and its potential to diminish soil inoculum
Publisher: Wiley
Date: 21-12-2018
DOI: 10.1111/PPA.12795
Survey for Botrytis species associated with onion bulb rot in northern Tasmania, Australia
Publisher: Springer Science and Business Media LLC
Date: 2004
DOI: 10.1071/AP04046
In Planta Transcriptome and Proteome Profiles of Spongospora subterranea in Resistant and Susceptible Host Environments Illuminates Regulatory Principles Underlying Host–Pathogen Interaction
Publisher: MDPI AG
Date: 28-08-2021
Abstract: Spongospora subterranea is an obligate biotrophic pathogen, causing substantial economic loss to potato industries globally. Currently, there are no fully effective management strategies for the control of potato diseases caused by S. subterranea. To further our understanding of S. subterranea biology during infection, we characterized the transcriptome and proteome of the pathogen during the invasion of roots of a susceptible and a resistant potato cultivar. A total of 7650 transcripts from S. subterranea were identified in the transcriptome analysis in which 1377 transcripts were differentially expressed between two cultivars. In proteome analysis, we identified 117 proteins with 42 proteins significantly changed in comparisons between resistant and susceptible cultivars. The functional annotation of transcriptome data indicated that the gene ontology terms related to the transportation and actin processes were induced in the resistant cultivar. The downregulation of enzyme activity and nucleic acid metabolism in the resistant cultivar suggests a probable influence of these processes in the virulence of S. subterranea. The protein analysis results indicated that the majority of differentially expressed proteins were related to the metabolic processes and transporter activity. The present study provides a comprehensive molecular insight into the multiple layers of gene regulation that contribute to S. subterranea infection and development in planta and illuminates the role of host immunity in affecting pathogen responses.
Characterisation of Botrytis species associated with neck rot of onion in Australia
Publisher: Springer Science and Business Media LLC
Date: 2004
DOI: 10.1071/AP03077
Brevipalpus oncidii, a new record for Australia is not a vector of Orchid fleck virus
Publisher: Informa UK Limited
Date: 14-09-2017
Multiple mutations across the succinate dehydrogenase gene complex are associated with boscalid resistance in Didymella tanaceti in pyrethrum
Publisher: Public Library of Science (PLoS)
Date: 20-06-2019
Low-dose foliar treatments of the auxin analog 2,4-D reduce potato common scab and powdery scab for multiple potato cultivars and enhance root development
Publisher: Elsevier BV
Date: 10-2020
A review of the plant virus and viroid records for Tasmania
Publisher: Springer Science and Business Media LLC
Date: 10-06-2020
Grading seed potato lots to remove tubers with powdery scab damage may not eliminate the pathogen threat
Publisher: Springer Science and Business Media LLC
Date: 08-02-2016
Improving the Fungicide-Based Management of Ray Blight Disease in Tasmanian Pyrethrum Fields
Publisher: Scientific Societies
Date: 06-2008
Abstract: Ray blight disease, caused by Phoma ligulicola var. inoxydablis, is a serious threat to the Tasmanian pyrethrum industry. The management of this disease relies upon the strategic application of fungicides in early spring. A range of fungicides were assessed for their efficacy in controlling ray blight disease in Tasmanian pyrethrum fields, and the primary objective of this study was to increase fungicide options available to growers in different resistance groups. Fungicides were assessed under in vitro conditions, within five replicated-plot field trials over three seasons (2004 to 2006) and in single-plot trials over eight fields in 2005. In each of the field trials, regular assessments of disease intensity (defoliation severity and the incidence of stems with ray blight), stem height, and the number of flowers produced on each stem were made using stems as the primary s ling unit. Canopy reflectance at 830 nm and the Difference Vegetative Index, measured using a handheld multispectral radiometer, also were used to compare fungicide effects on green leaf area. The effect of fungicides on the dry weight of flowers, pyrethrin content within the flowers, flower maturity, and pyrethrin yield were determined. Under in vitro conditions, boscalid reduced both conidial germination and mycelial growth at concentrations of at least 0.16 μg/ml. In field trials 1 and 2 (in 2004), the premixed formulation of pyraclostrobin + boscalid (Pristine) increased pyrethrin yield by an average of 79% compared with nontreated plots over the two locations. Furthermore, in single-plot trials, pyraclostrobin + boscalid increased pyrethrin yield by 134 and 60% compared with the industry-recommended protocol (single application of azoxystrobin at 150 g a.i./ha [Amistar WG] and two additional applications of a tank mixture of difenoconazole at 125 g a.i./ha [Score] and chlorothalonil at 1,008 liters a.i./ha [Bravo 720] at 14- to 21-day intervals) and nontreated plots, respectively. In field trials 3 (in 2005) and 4 and 5 (in 2006), similar yield benefits also were produced by applying pyraclostrobin (Cabrio SC) or boscalid (Filan) alone or in combination with chlorothalonil (Bravo 720) at 1.4 liters of product per hectare, regardless of the rates of pyraclostrobin (250 and 125 g a.i./ha) and boscalid (500 and 250 g a.i./ha) used. These data were used to recommend the incorporation of boscalid to improve the fungicide-based management of ray blight disease. This decreases the number of applications of both strobilurin and triazole fungicides which have been used extensively for the management of ray blight and other diseases in Tasmanian pyrethrum fields and are prone to fungicide resistance development.
Resting Spore Dormancy and Infectivity Characteristics of the Potato Powdery Scab Pathogen Spongospora subterranea
Publisher: Wiley
Date: 23-03-2017
DOI: 10.1111/JPH.12565
Viruses and Viroids Infecting Hop : Significance, Epidemiology, and Management
Publisher: Scientific Societies
Date: 03-2008
Quantifying Loss Caused by Ray Blight Disease in Tasmanian Pyrethrum Fields
Publisher: Scientific Societies
Date: 09-2007
Abstract: The efficacy of newly implemented fungicide recommendations on reducing the intensity of ray blight disease caused by Phoma ligulicola to achieve site-specific attainable yield potentials in Tasmanian pyrethrum fields was quantified over two seasons in 46 and 51 fields during the 2003 and 2004 growing seasons, respectively. Disease intensity and yield in two plots (10 × 24 m), one following the commercial fungicide protocol recommendations and the second receiving no fungicide, were assessed in each pyrethrum field. The commercial fungicide protocol consisted of one application of azoxystrobin at 150 g a.i./ha, followed by two applications of a tank mixture of difenoconazole at 125 g a.i./ha and chlorothalonil at 1,008 liters a.i./ha at 14- to 21-day intervals. This program resulted in significant decreases in defoliation severity and the incidence of stems and flowers with ray blight, and increases in the height of stems and number of flowers produced per stem in October and November. In plots receiving the commercial fungicide protocol, the dry weight of flowers was increased by 76 and 68% in 2003 and 2004, respectively. Moreover, pyrethrin yield increased by 81 and 78% when the commercial fungicide protocol was used compared with the nontreated plots. Tobit regression was used to examine the relationships and thresholds among disease intensity measures (defoliation severity, stem severity, and incidence of flowers with ray blight) assessed just prior to harvest. This regression utilized a left-censored regression model to define subminimal thresholds, as none of the disease intensity measures could be less than 0. Defoliation severity had a threshold of 35.3% before stem severity linearly increased and a threshold of 38.2% before the incidence of flowers with ray blight linearly increased. Finally, the threshold for stem severity was 13.7% before the incidence of flowers with ray blight linearly increased. These thresholds can be used to assist growers in making disease management decisions with the objective of minimizing loss of flowers by maintaining defoliation severity below the critical point at which the incidence of flowers with ray blight begins to linearly increase.
Incidence of weed reservoirs and vectors of tomato spotted wilt tospovirus on southern Tasmanian lettuce farms
Publisher: Wiley
Date: 04-1998
Use of a Multispectral Radiometer for Noninvasive Assessments of Foliar Disease Caused by Ray Blight in Pyrethrum
Publisher: Scientific Societies
Date: 11-2007
Abstract: Foliar disease due to ray blight (Phoma ligulicola) in pyrethrum was quantified at three locations over 2 years in Tasmania, Australia. To obtain a range of ray blight disease intensities, replicated plots were treated with fungicides that varied in efficacy to control ray blight. Visual disease assessments and measurement of canopy reflectance were made at least once during spring (September through December). Visual assessments involved removal of flowering stems at ground level from which measurements of defoliation severity and the incidence of stems with ray blight were obtained. Reflectance of sunlight from pyrethrum canopies was measured at 485, 560, 660, 830, and 1,650 nm using a handheld multispectral radiometer. Measurements from these wavelengths also were used to calculate all possible reflectance ratios, as well as four vegetative indices. Relationships between wavelength bands, reflectance ratios, vegetative indices, and disease intensity measures were described by linear regression analyses. Several wavelength bands, ratios, and vegetative indices were significantly related in a linear fashion to visual measures of disease intensity. The most consistent relationships, with high R 2 and low coefficients of variation values, varied with crop growth stage over time. The ratio 830/560 was identified as the best predictor of stem height, defoliation severity, and number of flowers produced on each stem in October. However, reflectance within the near-infrared range (830 nm) and the difference vegetative index was superior in November. The use of radiometric assessment of disease was noninvasive and provided savings in disease assessment time, which is critical where visual assessment is difficult and requires destructive s ling, as with pyrethrum.
Relationship between the application of foliar chemicals to reduce common scab disease of potato and correlation with thaxtomin A toxicity
Publisher: Scientific Societies
Date: 2012
Abstract: Production of the phytotoxin thaxtomin A by pathogenic Streptomyces spp. is essential for induction of common scab disease in potato. The disease can be significantly reduced by a range of chemicals applied as foliar sprays before tuber initiation. We tested a range of chemicals that had previously demonstrated varying capacities to reduce common scab for both disease suppression and their ability to inhibit thaxtomin A toxicity in both ‘Desiree’ and ‘Russet Burbank’ potato. Our results for disease suppression generally supported previous studies. Our tuber slice assays with thaxtomin A showed a strong correlation between the ability of the chemical to suppress common scab symptom development and the ability of the chemical to inhibit thaxtomin A toxicity. A Bayesian measurement error linear regression model was derived for each cultivar and trial and demonstrated a clear positive relationship between disease and thaxtomin-A-induced necrosis. The relationships obtained were much stronger than would have been obtained without adjustment for measurement error. This demonstrates that disease mitigation using chemical foliar sprays is strongly correlated with the ability of the chemical to inhibit thaxtomin A toxicity, suggesting this mechanism as a key mode of action for understanding this novel disease control strategy.
Synthesis and phytotoxicity of structural analogues of thaxtomin natural products
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/CH10006
Abstract: Structural analogues of the phytotoxic thaxtomin natural products have been synthesized by building upon a piperazinedione core and from l-phenylalanine. The compounds were evaluated for their phytotoxic activity against Arabidopsis thaliana seedlings and some of the key features for activity have been identified.
Resistance to phloem transport of potato leafroll virus in potato plants
Publisher: Microbiology Society
Date: 12-1992
DOI: 10.1099/0022-1317-73-12-3219
Abstract: A 'double-graft sandwich' technique in which sections of potato stem from different potato cultivars were grafted between a susceptible healthy stock plant and a potato leafroll virus (PLRV)-infected scion was used to study the rate of phloem transport of PLRV in cultivars differing in resistance to PLRV infection (IR) and accumulation (AR). Resistance to phloem transport (i.e. delayed PLRV systemic movement) was found in Bismark cultivar (IR A(S)). This was independent of IR and AR as the rate of movement in Bismark cultivar was markedly slower than that in Omega and Spunta (IR AR), Delaware (I(S) AR), and Desiree and Renova (I(S) A(S)) cultivars. It operated in Bismark cultivar stems of two different ages, but did not operate against potato virus X (PVX) and was not influenced by previous infection with this virus. Aphid vector (Myzus persicae) feeding preferences and colonization rates differed between cultivars, but the cultivar characteristics responsible were unrelated to IR, AR or resistance to phloem transport. Delayed systemic movement of PLRV out of leaves inoculated with viruliferous aphids was independent of AR and resistance to phloem transport, and remained unaffected by previous infection with PVX. It was also independent of cultivar factors causing different aphid feeding preferences and colonization rates, but may be linked to IR.
Significance of secondary infections with lily symptomless carlavirus to cut-flower production of Lilium
Publisher: Wiley
Date: 08-1996
Development of a Fungicide-Based Management Strategy for Foliar Disease Caused by Phoma ligulicola in Tasmanian Pyrethrum Fields
Publisher: Scientific Societies
Date: 10-2005
DOI: 10.1094/PD-89-1114
Abstract: The efficacy of a range of fungicides were assessed under in vitro conditions in four field trials over three seasons for the management of ray blight of pyrethrum, caused by the fungus Phoma ligulicola in Tasmania. Fungicides belonging to the demethylation inhibitor group, including prochloraz, tebuconazole, difenoconazole, and cyproconazole, produced the most significant reduction in mycelial growth in vitro compared with unamended controls. Significant reductions in germination of conidia resulted from low concentrations of azoxystrobin. In the field, azox-ystrobin (as Amistar) at a rate of 300 g of product/ha significantly decreased disease intensity and increased pyrethrin yield (kg/ha) in all seasons. Applications of either azoxystrobin or difenoconazole (as Score) at a rate of 250 ml of product/ha in early spring were the most effective, whereas no significant benefit was demonstrated from applications in autumn. Over all seasons, azoxystrobin applications resulted in double the weight of flowers produced compared with nontreated areas, whereas increases in pyrethrin content within the flowers were season and location specific. Application of azoxystrobin and chlorothalonil (as Bravo 720) at a rate of 1.4 liters of product/ha resulted in a 45 to 48% increase in flowers, reduced defoliation, and increased stem diameter. The weight of in idual flowers and flower maturity was not significantly affected by fungicide application. These data provide the basis for cost-effective management of this disease.
Optimal rates of 2,4-dichlophenoxyacetic acid foliar application for control of common scab in potato
Publisher: Wiley
Date: 04-06-2014
DOI: 10.1111/AAB.12138
The effect of irrigation strategies during tuber initiation on marketable yield and development of common scab disease of potato in Russet Burbank in Tasmania
Publisher: Springer Science and Business Media LLC
Date: 09-2001
DOI: 10.1007/BF02357902
Robustness of industrial crops in high production cost agricultural systems - dealing with market flux
Publisher: OMICS Publishing Group
Date: 2014
Chemotaxis and Motility of Spongospora subterranea Zoospores in Response to Potato Root Exudate Constituents and pH
Publisher: Scientific Societies
Date: 07-2023
DOI: 10.1094/PHYTO-04-21-0176-R
Abstract: Spongospora subterranea f. sp. subterranea is an important pathogen of potato responsible for major losses in most potato growing regions of the world. Infection is initiated by bi-flagellated motile zoospores released from long-lived resting spores. Zoospore chemotaxis to the host plant root is widely believed to be stimulated by host root exudate compounds, although direct evidence is lacking. This study refined the traditional chemotaxis capillary assay. With this we provided the first empirical evidence of S. subterranea zoospore chemotaxis. In idual potato root exudate metabolites were either taxis neutral, inhibitory, or attractant to the zoospores. L-glutamine was the strongest chemoattractant, while spermine was the most inhibitory. Zoospore motility and chemotaxis were constrained by strongly acidic or alkaline solutions of pH 5.3 and 8.5, respectively. Beyond pH, ionic constituents of the test solution affected zoospore motility as Sorensen’s phosphate buffer stalled zoospore motility, but HEPES buffer at the same concentration and pH had little or no negative motility effect. Zoospore motility, as characterized by several parameters, influenced chemotaxis. Among the parameters measured, total distance travelled was the best predictor of zoospore chemotaxis. The characterization of environmental and ecological effects on zoospore motility and chemotaxis highlights useful targets for S. subterranea disease control through manipulation of zoospore taxis or selection of host resistance traits.
Phylogenetic analysis of the downy mildew pathogen of oilseed poppy in Tasmania, and its detection by PCR
Publisher: Elsevier BV
Date: 02-2004
DOI: 10.1017/S095375620300916X
Abstract: Downy mildew of oilseed poppy (Papaver somniferum) has become a serious disease issue for the Tasmanian poppy industry since its first record in 1996. Previous reports have reported the pathogen as Peronospora arborescens, which is differentiated from the related species P. cristata, also known to infect Papaver spp., by conidium dimensions alone. This study investigated the taxonomic status of the downy mildew pathogen, using both morphological characters and molecular analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA). The inherent variability of conidium dimensions made differentiation of species difficult. Sequence homology and phylogenetic analyses of the ITS region showed the pathogen to be more closely related to P. cristata than P. arborescens. It is therefore proposed that downy mildew of oilseed poppy in Tasmania be reattributed to the pathogen P. cristata. In addition to this work, PCR primers have been developed for the specific detection of the downy mildew pathogen in Tasmania.
Development and validation of a novel rapid in vitro assay for determining resistance of potato cultivars to root attachment by Spongospora subterranea zoospores
Publisher: Wiley
Date: 25-10-2023
DOI: 10.1111/PPA.13659
Abstract: Spongospora subterranea f. sp. subterranea is a major pathogen of potatoes leading to losses in tuber quality and yield. Disease can be expressed as root infection, root galling and tuber lesions, the latter known as powdery scab. Attachment of zoospores to potato root hairs is the first step before infection of roots and disease development. Root hair infection results in root dysfunction leading to impaired plant productivity and yield. Varieties vary in their susceptibility to root and tuber disease however, varietal screening is both time and resource intensive. Furthermore, traditional screens assess root galling or tuber disease and not root infection. In this study, we determined optimal conditions for zoospore release and attachment of zoospores to plant roots and used this information to develop an in vitro bioassay to assess resistance to zoospore root attachment among 153 potato lines and cultivars. Optimal zoospore release occurred at 20°C in Hoagland's solution in a rapid and synchronized manner over the first 2 days, followed by a steep decline. The extent of zoospore root attachment varied with cultivar (Iwa Agria Russet Burbank Gladiator), region of the root maturation zone (lower middle upper) and temperature (greatest zoospore root attachment occurring at 15°C). Further comparisons suggested efficiency of zoospore root attachment was also generally associated with known variety resistance to powdery scab, zoosporangial infection and root galling, with a few notable exceptions. The bioassay proved to be a rapid and robust method for screening cultivar resistance to zoospore root attachment.
A comparison of potato seed-tuber sampling strategies using visual and DNA analyses to estimate incidence of major seed tuber-borne pathogens
Publisher: Springer Science and Business Media LLC
Date: 12-04-2014
Abundance of Poleroviruses within Tasmanian Pea Crops and Surrounding Weeds, and the Genetic Diversity of TuYV Isolates Found
Publisher: MDPI AG
Date: 30-07-2022
DOI: 10.3390/V14081690
Abstract: The genus Polerovirus contains positive-sense, single-stranded RNA plant viruses that cause significant disease in many agricultural crops, including vegetable legumes. This study aimed to identify and determine the abundance of Polerovirus species present within Tasmanian pea crops and surrounding weeds that may act as virus reservoirs. We further sought to examine the genetic ersity of TuYV, the most commonly occurring polerovirus identified. Pea and weed s les were collected during 2019–2020 between October and January from thirty-four sites across three different regions (far northwest, north, and midlands) of Tasmania and tested by RT-PCR assay, with selected s les subject to next-generation sequencing. Results revealed that the presence of polerovirus infection and the prevalence of TuYV in both weeds and pea crops varied across the three Tasmanian cropping regions, with TuYV infection levels in pea crops ranging between 0 and 27.5% of tested plants. Overall, two species members from each genus, Polerovirus and Potyvirus, one member from each of Luteovirus, Potexvirus, and Carlavirus, and an unclassified virus from the family Partitiviridae were also found as a result of NGS data analysis. Analysis of gene sequences of the P0 and P3 genes of Tasmanian TuYV isolates revealed substantial genetic ersity within the collection, with a few isolates appearing more closely aligned with BrYV isolates. Questions remain around the differentiation of TuYV and BrYV species. Phylogenetic inconsistency in the P0 and P3 ORFs supports the concept that recombination may have played a role in TuYV evolution in Tasmania. Results of the evolutionary analysis showed that the selection pressure was higher in the P0 gene than in the P3 gene, and the majority of the codons for each gene are evolving under purifying selection. Future full genome-based analyses of the genetic variations will expand our understanding of the evolutionary patterns existing among TuYV populations in Tasmania.
Shotgun Proteomics as a Powerful Tool for the Study of the Proteomes of Plants, Their Pathogens, and Plant–Pathogen Interactions
Publisher: MDPI AG
Date: 19-01-2022
DOI: 10.3390/PROTEOMES10010005
Abstract: The interaction between plants and pathogenic microorganisms is a multifaceted process mediated by both plant- and pathogen-derived molecules, including proteins, metabolites, and lipids. Large-scale proteome analysis can quantify the dynamics of proteins, biological pathways, and posttranslational modifications (PTMs) involved in the plant–pathogen interaction. Mass spectrometry (MS)-based proteomics has become the preferred method for characterizing proteins at the proteome and sub-proteome (e.g., the phosphoproteome) levels. MS-based proteomics can reveal changes in the quantitative state of a proteome and provide a foundation for understanding the mechanisms involved in plant–pathogen interactions. This review is intended as a primer for biologists that may be unfamiliar with the erse range of methodology for MS-based shotgun proteomics, with a focus on techniques that have been used to investigate plant–pathogen interactions. We provide a summary of the essential steps required for shotgun proteomic studies of plants, pathogens and plant–pathogen interactions, including methods for protein digestion, identification, separation, and quantification. Finally, we discuss how protein PTMs may directly participate in the interaction between a pathogen and its host plant.
Yield and cooking qualities of somaclonal variants of cv. Russet Burbank selected for resistance to common scab disease of potato
Publisher: Wiley
Date: 08-2010
Molecular variation of hop mosaic virus isolates
Publisher: Springer Science and Business Media LLC
Date: 03-08-2010
DOI: 10.1007/S00705-010-0780-3
Abstract: Hop mosaic virus (HpMV), a member of the genus Carlavirus, is importance to hop production worldwide. We identified variation in nucleic and amino acid sequences among 23 HpMV isolates from Australia, the USA, the Czech Republic, South Africa and Japan using a 1,455-bp fragment covering the 3' end of the virus genome including ORFs 4, 5 and 6. Three clusters of two or more isolates were identified in phylogenies of the total nucleotide sequence and the coat protein (ORF5) amino acid sequence. Two of these clusters combined in analyses of ORF4 and ORF6 amino acid sequences. Isolates from within and outside of Australia were found in each cluster, indicating that sequence variation was not associated with geographic source. Monitoring of HpMV variants in the field and evaluation of the impact of variants on vector association, rate of spread, and hop yield and quality can now be undertaken.
Occurrence of viruses within Tasmanian vegetable crops and identification of a novel Polerovirus infecting pea
Publisher: Springer Science and Business Media LLC
Date: 11-01-2012
Influence of benzimidazole fungicides on incidence of Botrytis allii infection of onion leaves and subsequent incidence onion neck rot in storage in Tasmania, Australia
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/EA05028
Abstract: Neck rot of onion caused by Botrytis spp., including B. allii, has previously been controlled in Australia with the fungicide Benlate (benomyl). Production of Benlate has recently ceased, therefore a field trial was conducted to examine the efficacy of alternative benzimidazoles fungicides. The trial compared 2 carbendazim fungicides (Marvel and Spin Flo) at 3 rates of application with Benlate applied at commercial rates and to non-treated plots in a randomised complete block design with 4 replicate plots per treatment. Fungicides were applied at 89, 96, 112 and 119 days after sowing. Plots were sprayed with inoculum consisting of a suspension of B. allii conidia 103 days after sowing. The incidence of B. allii infection in leaves was estimated 10 times during the season by collection and incubation of leaf s les. Fifty-six days after inoculum application the mean incidence of B. allii in leaves from fungicide treatments ranged from 0 to 10%, significantly lower (P .05) than that of non-treated plots (28.8%). The mean incidence of neck rot in bulb s les after 3 months of storage ranged from 1.0 to 9.9% in fungicide treatments, significantly (P .05) lower than that of non-treated plots (63.4%). The incidence of B. allii leaf infection in plots s led at different times during the season and the incidence of neck rot in storage were all significantly correlated (r = 0.42–0.61, P .01), except prior to application of inoculum.
Auxin-induced resistance to common scab disease of potato linked to inhibition of thaxtomin A toxicity
Publisher: Scientific Societies
Date: 09-2008
Abstract: Production of the phytotoxin thaxtomin A by pathogenic Streptomyces spp. is essential for induction of common scab disease in potato. Prior studies have shown that foliar application of sublethal concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and other auxin or auxin-like compounds significantly reduced severity and occurrence of common scab in subsequently produced tubers. However, the means of disease suppression by these compounds was not known. We confirm the disease suppressive activity of 2,4-D. Detailed tuber physiological examination showed that lenticel numbers, lenticel external dimensions, and periderm thickness and structure, physiological features believed to be critical to Streptomyces scabiei infection, were not substantially changed by 2,4-D treatments, negating a possible mechanism for disease suppression through alteration of these structures. In contrast, our studies show accumulation of 2,4-D in tubers of treated plants occurs and is associated with an enhanced tolerance to thaxtomin A. Applying 2,4-D to cultures of S. scabiei did not significantly alter in vitro growth of the pathogen. Thaxtomin A production by the pathogen was inhibited by 2,4-D, but only at the highest rate tested (1.0 mM), which is at least 200-fold more than is found in 2,4-D treated tubers. These data suggest 2,4-D has no direct effect on the pathogen or its virulence. Confirmatory evidence from studies with Arabidopsis thaliana seedlings demonstrated that the auxins 2,4-D and IAA ameliorate thaxtomin A toxicity. The evidence presented whereby auxin treatment inhibits toxicity of thaxtomin A secreted by the pathogen suggests a novel indirect means of disease suppression.
The tomato potato psyllid, Bactericera cockerelli (Sulc, 1909) (Hemiptera: Triozidae): a review of the threat of the psyllid to Australian solanaceous crop industries and surveillance for incursions in potato crops
Publisher: Wiley
Date: 15-10-2015
DOI: 10.1111/AEN.12129
Potato root exudation and release of Spongospora subterranea resting spore germination stimulants are affected by plant and environmental conditions
Publisher: Wiley
Date: 21-12-2017
DOI: 10.1111/JPH.12537
Resistance to infection and translocation of Tomato spotted wilt virus in potatoes
Publisher: Wiley
Date: 06-2001
Suberin deposition in potato periderm: a novel resistance mechanism against tuber greening
Publisher: Wiley
Date: 02-01-2020
DOI: 10.1111/NPH.16334
Abstract: Light-induced tuber greening is one of the most important quality defects of potato. Although varietal and maturity factors are known to affect greening resistance, physiological mechanisms of resistance are poorly understood. We proposed that physiological and biochemical factors within the tuber periderm provide resistance and hypothesised that resistance is primarily related to suberin content. We investigated differences in the tuber periderm between genotypes and tuber maturities that varied in greening propensity. We examined suberin and light-induced pigment accumulation, and phellem cell development and studied greening propensity in mutant and chemically treated tubers with enhanced suberisation. Resistance to greening was strongly linked to increased suberin in the periderm, which varied with variety and tuber maturity. Furthermore, greening was reduced in mutant and chemically treated tubers with enhanced suberisation. Increases in phellem cell layers and light-induced carotenoids and anthocyanins were identified as secondary resistance factors. Our work represents the first physiological mechanism of varietal and tuber maturity resistance to greening, expanding the known functionality of suberin and providing for the first time a biomarker that will aid producers and breeders in selection and improvement of potato varieties for greening resistance.
Occurrence of potato virus X strain group 1 in seed stocks of potato cultivars lacking resistance genes
Publisher: Wiley
Date: 12-1995
Incidence and pathology of common viruses of nerine in Tasmania
Publisher: Wiley
Date: 02-2000
Forecasting climate suitability of Australian hop growing regions for establishment of hop powdery and downy mildews
Publisher: Springer Science and Business Media LLC
Date: 2003
DOI: 10.1071/AP03056
Mechanisms of thaxtomin A-induced root toxicity revealed by a thaxtomin A sensitive Arabidopsis mutant (ucu2-2/gi-2)
Publisher: Springer Science and Business Media LLC
Date: 30-10-2016
DOI: 10.1007/S00299-015-1888-4
Abstract: The Arabidopsis mutant ( ucu2 - 2/gi - 2 ) is thaxtomin A, isoxaben and NPA-sensitive indicated by root growth and ion flux responses providing new insights into these compounds mode of action and interactions. Thaxtomin A (TA) is a cellulose biosynthetic inhibitor (CBI) that promotes plant cell hypertrophy and cell death. Electrophysiological analysis of steady-state K(+) and Ca(2+) fluxes in Arabidopsis thaliana roots pretreated with TA for 24 h indicated a disturbance in the regulation of ion movement across the plant cell membrane. The observed inability to control solute movement, recorded in rapidly growing meristematic and elongation root zones, may partly explain typical root toxicity responses to TA treatment. Of note, the TA-sensitive mutant (ucu2-2/gi-2) was more susceptible with K(+) and Ca(2+) fluxes altered between 1.3 and eightfold compared to the wild-type control where fluxes altered between 1.2 and threefold. Root growth inhibition assays showed that the ucu2-2/gi-2 mutant had an increased sensitivity to the auxin 2,4-D, but not IAA or NAA it also had increased sensitivity to the auxin efflux transport inhibitor, 1-naphthylphthalamic acid (NPA), but not 2,3,5- Triiodobenzoic acid (TIBA), when compared to the WT. The NPA sensitivity data were supported by electrophysiological analysis of H(+) fluxes in the mature (but not elongation) root zone. Increased sensitivity to the CBI, isoxaben (IXB), but not dichlobenil was recorded. Increased sensitivity to both TA and IXB corresponded with higher levels of accumulation of these toxins in the root tissue, compared to the WT. Further root growth inhibition assays showed no altered sensitivity of ucu2-2/gi-2 to two other plant pathogen toxins, alternariol and fusaric acid. Identification of a TA-sensitive Arabidopsis mutant provides further insight into how this CBI toxin interacts with plant cells.
Quantifying risk factors associated with light-induced potato tuber greening in retail stores
Publisher: Public Library of Science (PLoS)
Date: 18-09-2020
Seedborne Infection of Pyrethrum by Phoma ligulicola
Publisher: Scientific Societies
Date: 07-2006
DOI: 10.1094/PD-90-0891
Abstract: The incidence of Phoma ligulicola in Tasmanian pyrethrum seed and methods of managing seedborne mycoflora were determined. Fourteen different fungi were regularly isolated from seed, including Alternaria tenuissima, Stemphylium botryosum, and P. ligulicola, which have been documented as pathogens of pyrethrum. Comparisons between the incidence of these fungi from seed surface-sterilized with sodium hypochlorite and nontreated seed indicated they occurred both within and on the outside of the seed. A polymerase chain reaction (PCR) test for the detection of P. ligulicola was also developed, with a detection limit of 800 fg of fungal DNA. The assay detected infested seed lots down to an incidence of 0.5%. Reliable lification of the target DNA was achieved with the addition of bovine serum albumin to reduce the influence of inhibitors from pyrethrum seed. Agar plate tests and PCR demonstrated variability with pyrethrum cultivars in the presence and viability of P. ligulicola in seed. Effective management strategies for the reduction of seedborne P. ligulicola included the regular use of fungicides for reducing foliar disease intensity in the seed fields prior to harvest. Seed treatments with fludioxonil and thiabendazole/thiram also significantly reduced the incidence of seedborne P. ligulicola and increased seed germination and seedling survival.
Varietal response to groundnut rosette disease and the first report of Groundnut ringspot virus in Ghana
Publisher: Scientific Societies
Date: 05-2016
DOI: 10.1094/PDIS-07-15-0838-RE
Abstract: Twelve cultivars of groundnut were screened in field trials for resistance to groundnut rosette disease (GRD), caused by coinfection with Groundnut rosette assistor virus (GRAV), Groundnut rosette virus (GRV), and its satellite RNA in the coastal savannah of Ghana. ‘Oboshie’ groundnut was rated as highly resistant ‘Bremaowuo’, ‘Nkatefufuo’, and ‘Behenase’ as resistant and ‘Nkosuor’, ‘Kumawu’, and ‘Otuhia’ as moderately resistant. GRAV infection rates of 11.8 to 61.8% (dry season) and 13.9 to 100% (wet season) were found, which included symptomless plants, suggesting that some lacked coinfection with GRV and its satellite. Chlorotic ringspot and line-pattern symptoms were observed, suggesting infection with Groundnut ringspot virus (GRSV). Virus identity was confirmed by enzyme-linked immunosorbent assay, reverse-transcription polymerase chain reaction, and licon sequencing. This is the first report of GRSV in Ghana. GRSV infection rates were 0.0 to 69.5% (dry season) and 26.1 to 69.5% (wet season). Mixed infections of GRAV and GRSV were common in all cultivars except Nkosuor and Bremaowuo in the dry season. Most cultivars graft inoculated with GRD showed significantly reduced height, leaf area, chlorophyll content, dry haulm weight, and seed yield compared with healthy plants. The sources of resistance to GRD and possibly GRAV and GRSV identified in this study could be exploited in groundnut breeding programs.
Tan spot: a new disease of pyrethrum caused by Microsphaeropsis tanaceti sp.nov
Publisher: Wiley
Date: 18-11-2008
Plant Cell Growth and Ion Flux Responses to the Streptomycete Phytotoxin Thaxtomin A: Calcium and Hydrogen Flux Patterns Revealed by the Non-invasive MIFE Technique
Publisher: Oxford University Press (OUP)
Date: 04-2005
DOI: 10.1093/PCP/PCI069
Abstract: Thaxtomin A, a key phytotoxin produced by plant pathogenic Streptomyces sp., is implicit in common scab disease expression in potato. Primary targets and modes of action of thaxtomin A toxicity in plant cells are not well understood. In this work, early signalling events associated with thaxtomin A toxicity were studied using the ion-selective microelectrode ion flux estimation (MIFE) technique. Thaxtomin A-induced changes in net ion fluxes were measured across the plasma membrane (PM) of root and pollen tube tissue in Arabidopsis thaliana and tomato. Within a minute after toxin application, a rapid and short-lived Ca2+ influx was observed. Well ahead of the marked inhibition of root growth, a significant shift towards net H+ efflux across the PM occurred in all tissues. Similar to root tissues, thaxtomin A significantly modified ion flux profiles from growing pollen tubes. Thaxtomin A was more effective in young, physiologically active tissues (root elongation zone or pollen tube apex), suggesting a higher density of thaxtomin A-binding sites in these regions. Overall, our data provide the first evidence that thaxtomin A triggers an early signalling cascade, which may be crucial in plant-pathogen interactions. It also suggests a possible interaction between thaxtomin A and PM auxin receptors, as revealed from experiments on the auxin-sensitive ucu2-2/gi2 A. thaliana mutant.
A polymerase chain reaction assay for cucumber mosaic virus in lupin seeds
Publisher: CSIRO Publishing
Date: 1993
DOI: 10.1071/AR9930041
Abstract: Seed is the main source of infection of narrow-leafed lupin (Lupinus angustifolius) crops by cucumber mosaic virus (CMV). The ELISA procedure is currently used for large-scale, routine testing of lupin seed s les, but a more sensitive, reliable and labour-saving assay is needed which detects levels of seed infection as low as 0.1%. A Polymerase Chain Reaction (PCR) using ground dry seed s les was developed for this purpose. Primers based on concensus sequences of eight published CMV coat protein cDNAs (RNA3) of CMV subgroups 1 and 2 were used. The assay involved (1) a reverse transcription step for cDNA synthesis and (2) lification of a specific fragment (482-501 bp depending on the strain) by PCR. Two methods of extracting virus from infected lupin material were used: (i) a rapid procedure which was effective for s les with higher levels of infection, e.g. infected leaves and 20.5% infected seed (ii) a phenol-chloroform procedure, which led to greater sensitivity, enabling reliable detection of 0.1% seed infection. It detected CMV in 16 commercial seed s les (0.1-8% seed infection) belonging to seven cultivars from 12 different localities. Both methods were suitable for routine testing of the flour derived from grinding dry seed. On dissection of infected seeds, CMV was detected in the cotyledons and embryo and usually in or on the testa. The PCR assay detected virus from both CMV subgroups, but only subgroup 2 was found in lupin seed s les. The two CMV subgroups can be distinguished by digestion of lified DNA with the restriction enzyme EcoRI only CMV strains of subgroup 2 are digested to yield two fragments of size 330 and 170 bp.
Host range of Peronospora somniferi and Pe. meconopsidis within selected members of the Papaveraceae under controlled conditions
Publisher: Wiley
Date: 05-09-2020
DOI: 10.1111/JPH.12947
Resistance to multiple tuber diseases expressed in somaclonal variants of the potato cultivar Russet Burbank
Publisher: Hindawi Limited
Date: 2014
DOI: 10.1155/2014/417697
Abstract: Multiple disease resistance is an aim of many plant breeding programs. Previously, novel somatic cell selection was used to generate potato variants of “Russet Burbank” with resistance to common scab caused by infection with an actinomycete pathogen. Coexpression of resistance to powdery scab caused by a protozoan pathogen was subsequently shown. This study sought to define whether this resistance was effective against additional potato tuber diseases, black scurf, and tuber soft rot induced by fungal and bacterial pathogens. Pot trials and in vitro assays with multiple pathogenic strains identified significant resistance to both tuber diseases across the potato variants examined the best clone A380 showed 51% and 65% reductions in disease severity to tuber soft rot and black scurf, respectively, when compared with the parent line. The resistance appeared to be tuber specific as no enhanced resistance was recorded in stolons or stem material when challenged Rhizoctonia solani that induces stolon pruning and stem canker. The work presented here suggests that morphological characteristics associated with tuber resistance may be the predominant change that has resulted from the somaclonal cell selection process, potentially underpinning the demonstrated broad spectrum of resistance to tuber invading pathogens.
Metabolomes of potato root exudates: compounds that stimulate resting spore germination of the soil-borne pathogen Spongospora subterranea
Publisher: American Chemical Society (ACS)
Date: 28-09-2016
Abstract: Root exudation has importance in soil chemical ecology influencing rhizosphere microbiota. Prior studies reported root exudates from host and nonhost plants stimulated resting spore germination of Spongospora subterranea, the powdery scab pathogen of potato, but the identities of stimulatory compounds were unknown. This study showed that potato root exudates stimulated S. subterranea resting spore germination, releasing more zoospores at an earlier time than the control. We detected 24 low molecular weight organic compounds within potato root exudates and identified specific amino acids, sugars, organic acids, and other compounds that were stimulatory to S. subterranea resting spore germination. Given that several stimulatory compounds are commonly found in exudates of erse plant species, we support observations of nonhost-specific stimulation. We provide knowledge of S. subterranea resting spore biology and chemical ecology that may be useful in formulating new disease management strategies.
Zoosporangial root infection of tomato by Spongospora subterranea in hydroponic and glasshouse culture results in diminished plant growth
Publisher: Wiley
Date: 26-03-2018
DOI: 10.1111/JPH.12701
Detection of Two Peronospora spp., Responsible for Downy Mildew, in Opium Poppy Seed
Publisher: Scientific Societies
Date: 11-2018
DOI: 10.1094/PDIS-03-18-0503-RE
Abstract: Downy mildew is a serious threat to opium poppy production globally. In recent years, two pathogen species, Peronospora somniferi and Peronospora meconopsidis, which induce distinct symptoms, have been confirmed in Australia. In order to manage the spread of these pathogens, identifying the sources of inoculum is essential. In this study, we assessed pathogen presence associated with poppy seed. We developed PCR and qPCR assays targeting the coxI and coxII gene regions, for the detection, differentiation, and quantification of P. somniferi and P. meconopsidis in poppy seed. These results were complemented and compared with direct seed histological examination and a seed washing combined with viability staining for oospore detection. The majority of seed lots from all harvest years contained detectable P. meconopsidis, the earliest (1987) predating the first official record of the disease in Tasmania (1996). In contrast, only seed lots harvested in 2012 or later contained P. somniferi, evidence of its more recent introduction. P. meconopsidis contamination was estimated to be as high as 33.04 pg DNA/g of seed and P. somniferi as high as 35.17 pg DNA/g of seed. Incidence of pathogen contamination of seeds, estimated via a group testing protocol, ranged from 0 to 9% (P. meconopsidis) or 0 to 11% (P. somniferi). Mycelia were predominately found external to the seed coat. Seed washing and viability staining demonstrated that putatively viable oospores were present in the majority of seed lots. Transmission testing confirmed both pathogens can be successfully transmitted from infested seed to infected seedling. PCR and qPCR pathogen assays were found to be reliable and offer a routine test for determining pathogen inoculum in poppy seeds.
Effect of viruses on agronomic and brewing characteristics of four hop (Humulus lupulus) cultivars in Australia
Publisher: Wiley
Date: 02-2002
Spatiotemporal spread of Potato carlavirus S and Potato potexvirus X in seed potato in Tasmania, Australia
Publisher: Scientific Societies
Date: 2007
DOI: 10.1094/PHP-2007-0726-07-RS
Abstract: The spatial and temporal distribution of Potato virus S (PVS) and Potato virus X (PVX) was studied in two trials within each of four commercial fields of seed potato var. Russet Burbank in Tasmania, Australia. In the first trial (plots) 20 leaflets were collected from each of 49 plots (each approximately 8 m wide by 10 m long), with plots arranged in a 7-×-7 lattice. In the second trial (transects), leaflets were collected at 1-m intervals along seven adjacent, 50-m long rows. The mean incidence of PVS increased during the season by 5.2% in one of four plot trials and 25.5% in one of four transect trials. The mean incidence of PVX increased during the season by 10.1%, in one of two transect trials. Spatial Analysis by Distance IndicEs and ordinary runs analysis detected aggregation of PVS infected plants early in the season in one and two fields respectively, suggesting transmission during seed-cutting or during planting. An increase in PVS incidence mid- to late season in one field was associated with aggregation of PVS along, but not across rows, which may be related to the closer plant spacing within rows and hence increased potential for mechanical transmission along rows. Results suggested limited spread of PVS and PVX occurred within crops during the season. Accepted for publication 9 April 2007. Published 26 July 2007.
Adaptation of the Forecasting Model DOWNCAST for Determination of Downy Mildew Epidemics of Oilseed Poppy in Tasmania, Australia
Publisher: Wiley
Date: 13-03-2008
Toughing it out?disease-resistant potato mutants have enhanced tuber skin defenses
Publisher: Scientific Societies
Date: 05-2016
DOI: 10.1094/PHYTO-08-15-0191-R
Abstract: Common scab, a globally important potato disease, is caused by infection of tubers with pathogenic Streptomyces spp. Previously, disease-resistant potato somaclones were obtained through cell selections against the pathogen’s toxin, known to be essential for disease. Further testing revealed that these clones had broad-spectrum resistance to erse tuber-invading pathogens, and that resistance was restricted to tuber tissues. The mechanism of enhanced disease resistance was not known. Tuber periderm tissues from disease-resistant clones and their susceptible parent were examined histologically following challenge with the pathogen and its purified toxin. Relative expression of genes associated with tuber suberin biosynthesis and innate defense pathways within these tissues were also examined. The disease-resistant somaclones reacted to both pathogen and toxin by producing more phellem cell layers in the tuber periderm, and accumulating greater suberin polyphenols in these tissues. Furthermore, they had greater expression of genes associated with suberin biosynthesis. In contrast, signaling genes associated with innate defense responses were not differentially expressed between resistant and susceptible clones. The resistance phenotype is due to induction of increased periderm cell layers and suberization of the tuber periderm preventing infection. The somaclones provide a valuable resource for further examination of suberization responses and its genetic control.
Enhanced resistance to common scab of potato through somatic cell selection in cv. Iwa with the phytotoxin thaxtomin A
Publisher: Wiley
Date: 11-01-2009
Incidence and Spatial Distribution of Viruses in Hop Gardens of Washington State
Publisher: Scientific Societies
Date: 06-2002
DOI: 10.1094/PDIS.2002.86.6.661
Abstract: The incidences of Hop latent virus (HpLV), Hop mosaic virus (HpMV), and American hop latent virus (AHLV), members of the genus Carlavirus, and Prunus necrotic ringspot virus and Apple mosaic virus, members of the genus Ilarvirus, were assessed for two hop cultivars, Horizon and Nugget, in Washington State. The spatial distribution of plants infected by the carlaviruses was assessed in two Horizon gardens in 2000 and one Nugget garden in 1993, 1994, and 1995. In the first Horizon garden (garden 1) and the Nugget garden, plants were separated by 2.1 m within and between rows. In these gardens, cultivation and the wide plant spacing discouraged contact between plants in either direction. In the second Horizon garden (garden 2), plants were separated by 4.3 m between rows and 1.0 m within rows. In all gardens, mechanical operations operated predominantly along rows however, the closer plant spacing within rows in garden 2 permitted contact between adjacent plants within rows. In both Horizon gardens, the distribution of plants infected with HpMV was aggregated within rows. However, the distribution of plants infected with HpLV and AHLV was strongly influenced by contact between plants. In the Nugget garden, the distribution of plants infected by all three carlaviruses was autocorrelated within rows by 1995.
Species composition and abundance of aphids in Australian hop gardens and their impact on spatiotemporal patterns of Carlavirus epidemics
Publisher: Wiley
Date: 08-2004
Receiver Operating Characteristic curve analysis determines association of individual potato foliage volatiles with onion thrips preference, cultivar and plant age
Publisher: Public Library of Science (PLoS)
Date: 26-07-2017
Editorial: Plant responses to phytophagous mites/thrips and search for resistance
Publisher: Frontiers Media SA
Date: 04-07-2019
Genetic and host-associated differentiation within Thrips tabaci Lindeman (Thysanoptera: Thripidae) and its links to Tomato spotted wilt virus-vector competence
Publisher: Springer Science and Business Media LLC
Date: 05-2013
DOI: 10.1038/HDY.2013.39
Managing and Monitoring Viral and Soil-Borne Pathogens in Tasmanian Potato Crops
Publisher: Springer Netherlands
Date: 2012
Optimisation of Sporosori Purification and Protein Extraction Techniques for the Biotrophic Protozoan Plant Pathogen Spongospora subterranea
Publisher: MDPI AG
Date: 08-07-2020
DOI: 10.3390/MOLECULES25143109
Abstract: Spongospora subterranea is a soil-borne plant pathogen responsible for the economically significant root and powdery scab diseases of potato. However, the obligate biotrophic nature of S. subterranea has made the detailed study of the pathogen problematic. Here, we first compared the benefits of sporosori partial purification utilizing Ludox® gradient centrifugation. We then undertook optimization efforts for protein isolation comparing the use of a urea buffer followed by single-pot solid-phase-enhanced s le preparation (SP3) and a sodium dodecyl sulphate (SDS) buffer followed by suspension-trapping (S-Trap). Label-free, quantitative proteomics was then used to evaluate the efficiency of the sporosori purification and the protein preparation methods. The purification protocol produced a highly purified suspension of S. subterranea sporosori without affecting the viability of the spores. The results indicated that the use of a combination of SDS and S-Trap for s le clean-up and digestion obtained a significantly higher number of identified proteins compared to using urea and SP3, with 218 and 652 proteins identified using the SP3 and S-Trap methods, respectively. The analysis of proteins by mass spectrometry showed that the number of identified proteins increased by approximately 40% after the purification of spores by Ludox®. These results suggested a potential use of the described spore purification and protein preparation methods for the proteomics study of obligate biotrophic pathogens such as S. subterranea.
Molecular variation of hop mosaic virus isolates
Publisher: Springer Science and Business Media LLC
Date: 03-08-2010
DOI: 10.1007/S00705-010-0780-3
Abstract: Hop mosaic virus (HpMV), a member of the genus Carlavirus, is importance to hop production worldwide. We identified variation in nucleic and amino acid sequences among 23 HpMV isolates from Australia, the USA, the Czech Republic, South Africa and Japan using a 1,455-bp fragment covering the 3' end of the virus genome including ORFs 4, 5 and 6. Three clusters of two or more isolates were identified in phylogenies of the total nucleotide sequence and the coat protein (ORF5) amino acid sequence. Two of these clusters combined in analyses of ORF4 and ORF6 amino acid sequences. Isolates from within and outside of Australia were found in each cluster, indicating that sequence variation was not associated with geographic source. Monitoring of HpMV variants in the field and evaluation of the impact of variants on vector association, rate of spread, and hop yield and quality can now be undertaken.
Temporal association of potato tuber development with susceptibility to common scab and Streptomyces scabiei-induced responses in the potato periderm
Publisher: Wiley
Date: 23-02-2011
Identification of Orchid fleck virus by Reverse Transcriptase-Polymerase Chain Reaction and Analysis of Isolate Relationships
Publisher: Wiley
Date: 12-2001
DOI: 10.1046/J.1439-0434.2001.00702.X
Abstract: Using reverse transcription‐polymerase chain reaction (RT‐PCR) tests with a primer complementary to a region of its nucleoprotein gene together with a polydT/SP6 primer, Orchid fleck virus (OFV) was detected in 34 s les of infected orchids of several different genera from world‐wide sources. The resulting DNA fragments were approximately 800 bp in length and their sequences were determined directly. Analysis of sequences of the major open reading frame (ORF) within the DNA fragments obtained showed the presence of two virus strains. The first group was of two isolates, the original Japanese isolate from which the primers were derived and one from Germany, and the second group contained 33 isolates from four continents. The sequences of different groups differed from one another by at least 15.6% (nucleotide) and 1.8% (amino‐acid), but the within‐group differences were much less ( .7% difference). A search of the international nucleotide database with the OFV sequences showed them to be related, but distantly, to nucleoprotein regions of the genomes of four plant‐infecting rhabdoviruses.
Multiplex PCR assay for the detection of Pantoea stewartii subsp. stewartii using species-specific genetic markers
Publisher: Springer Science and Business Media LLC
Date: 06-05-2012
The Relative Importance of Seed-borne Inoculum to Common Scab Disease of Potato and the Efficacy of Seed Tuber and Soil Treatments for Disease Control
Publisher: Wiley
Date: 1999
Occurrence of Actinomadura phage in organic mulches used for avocado plantations in Western Australia
Publisher: Canadian Science Publishing
Date: 04-1993
DOI: 10.1139/M93-057
Abstract: Phage infecting Actinomadura verrucosospora, Actinomadura pusilla, and Nocardiopsis flava were isolated from mulches applied to avocado trees at the University of Western Australia experimental plots. The physiochemical properties, plaque morphology, host range, and particle morphology of the phage isolated are described. Taxonomic implications of the reactions of some cell wall chemotype III actinomycetes to Actinomadura phage are also discussed.Key words: Actinomadura phage.
Determination of optimal timing of 2,4-dichlorophenoxyacetic acid foliar applications for common scab control in potato
Publisher: Wiley
Date: 15-07-2013
DOI: 10.1111/AAB.12050
First report of systemic downy mildew of opium poppy caused by Peronospora somniferi in Australia
Publisher: Scientific Societies
Date: 02-2017
Visual and Radiometric Assessments for Yield Losses Caused by Ray Blight in Pyrethrum
Publisher: Wiley
Date: 2008
Occurrence of potato virus X strain group 1 in seed stocks of potato cultivars lacking resistance genes
Publisher: Wiley
Date: 12-1995
Virus incidence in Australian hop (Humulus lupulus L.) gardens and cultivar differences in susceptibility to infection
Publisher: CSIRO Publishing
Date: 2000
DOI: 10.1071/AR99154
Abstract: 0uo Victoria’ (98%) was significantlyhigher than in ‘T11’ (58%), which was higher than‘Opal’ (31%). Results suggested that ‘Victoria’was more susceptible to infection by all 3 viruses than traditionally growncultivars and recently released or experimental cultivars. Planting with elitematerial and roguing of infected plants has been ineffective as a viruscontrol strategy with this cultivar.
Enhanced resistance to the cellulose biosynthetic inhibitors, thaxtomin A and isoxaben in Arabidopsis thaliana mutants, also provides specific co-resistance to the auxin transport inhibitor, 1-NPA
Publisher: Springer Science and Business Media LLC
Date: 2013
Incidence and effects of viruses on production of two newly adopted hop (Humulus lupulus) cultivars in Australia
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/AR04025
Abstract: The incidence and spread of Hop latent virus (HpLV), Hop mosaic virus (HpMV), and Apple mosaic virus (ApMV) in nurseries and gardens established with elite material (certified free of HpLV, HpMV, and ApMV by serological testing), and the effect of these viruses on production of 2 newly adopted hop (Humulus lupulus) cultivars were assessed in Tasmania, Australia. Infection by HpLV in Agate was associated with significant losses in dry cone yield of 40–70% compared with the yield of elite plants. Infection by HpLV in Agate was also associated with a 44% reduction in alpha acid levels and the cohumulone proportion of the alpha acids. However, in the second year, no significant reductions in levels of alpha acid and beta acid contents, or in the ratio of alpha to beta acids were detected. Plants infected by HpLV were also significantly shorter than elite plants in both seasons. No significant effects on growth or yield were detected for HpMV in Agate or for any of the virus combinations tested in Super Pride. The incidences and spread of HpLV, HpMV, and ApMV were consistently higher in Agate than in Super Pride and the incidences of all these viruses were higher at Forrester River than at Bushy Park and Gunns Plains. The presence of viruses in nurseries containing material propagated from elite mother plants is also of concern and may be contributing to high levels of virus incidence found soon after establishment. When combined, this information can be used to design control strategies for the Australian hop industry for these cultivars.
Potato Tuber Greening: a Review of Predisposing Factors, Management and Future Challenges
Publisher: Springer Science and Business Media LLC
Date: 21-03-2018
A polymerase chain reaction assay for cucumber mosaic virus in lupin seeds
Publisher: CSIRO Publishing
Date: 1993
DOI: 10.1071/AR9930041
Abstract: Seed is the main source of infection of narrow-leafed lupin (Lupinus angustifolius) crops by cucumber mosaic virus (CMV). The ELISA procedure is currently used for large-scale, routine testing of lupin seed s les, but a more sensitive, reliable and labour-saving assay is needed which detects levels of seed infection as low as 0.1%. A Polymerase Chain Reaction (PCR) using ground dry seed s les was developed for this purpose. Primers based on concensus sequences of eight published CMV coat protein cDNAs (RNA3) of CMV subgroups 1 and 2 were used. The assay involved (1) a reverse transcription step for cDNA synthesis and (2) lification of a specific fragment (482-501 bp depending on the strain) by PCR. Two methods of extracting virus from infected lupin material were used: (i) a rapid procedure which was effective for s les with higher levels of infection, e.g. infected leaves and 20.5% infected seed (ii) a phenol-chloroform procedure, which led to greater sensitivity, enabling reliable detection of 0.1% seed infection. It detected CMV in 16 commercial seed s les (0.1-8% seed infection) belonging to seven cultivars from 12 different localities. Both methods were suitable for routine testing of the flour derived from grinding dry seed. On dissection of infected seeds, CMV was detected in the cotyledons and embryo and usually in or on the testa. The PCR assay detected virus from both CMV subgroups, but only subgroup 2 was found in lupin seed s les. The two CMV subgroups can be distinguished by digestion of lified DNA with the restriction enzyme EcoRI only CMV strains of subgroup 2 are digested to yield two fragments of size 330 and 170 bp.
Resistance to potato leafroll virus infection and accumulation in potato cultivars and the effects of previous infection with other viruses on expression of resistance
Publisher: CSIRO Publishing
Date: 1993
DOI: 10.1071/AR9931891
Abstract: A selection of potato cultivars and breeding lines was evaluated for presence of resistance to infection with potato leafroll virus (PLRV) via viruliferous aphid vectors ( IR) and/or resistance to accumulation of PLRV antigen ( AR) in infected leaf tissue. Cultivars Aracy, Delcora, Omega and Spunta, and breeding lines BR63.15 and B71.240.2 carried both IR and AR , Bismark, Serrana INTA and L/T1 had alone and Delaware had AR alone. The other cultivars tested had neither. Within both the resistant and susceptible classes for AR, the level of PLRV antigen accumulation achieved varied with cultivar. Previous infection with potato virus X (PVX) or potato virus S (PVS) either alone or together did not diminish the expression of IR or AR. However, the presence of PVX sometimes significantly increased the accumulation of PLRV in susceptible cv. Desiree and this effect was most pronounced in mature leaves of older plants. In contrast, presence of PVX in susceptible cv. Desiree did not increase the numbers of plants becoming infected with PLRV. Identifying potato genotypes with and IR AR will help the Australian potato industry to select cultivars which become infected with PLRV more slowly under conditions of high infection pressure and/or are suitable for use as parental lines in breeding virus-resistant cultivars.
Effect of physio-chemical seed treatments on opium poppy downy mildews caused by Peronospora meconopsidis and P. somniferi
Publisher: Public Library of Science (PLoS)
Date: 10-04-2020
Phylogenetic analysis of the downy mildew pathogen of oilseed poppy in Tasmania, and its detection by PCR
Publisher: Elsevier BV
Date: 02-2004
DOI: 10.1017/S095375620300916X
Abstract: Downy mildew of oilseed poppy (Papaver somniferum) has become a serious disease issue for the Tasmanian poppy industry since its first record in 1996. Previous reports have reported the pathogen as Peronospora arborescens, which is differentiated from the related species P. cristata, also known to infect Papaver spp., by conidium dimensions alone. This study investigated the taxonomic status of the downy mildew pathogen, using both morphological characters and molecular analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA). The inherent variability of conidium dimensions made differentiation of species difficult. Sequence homology and phylogenetic analyses of the ITS region showed the pathogen to be more closely related to P. cristata than P. arborescens. It is therefore proposed that downy mildew of oilseed poppy in Tasmania be reattributed to the pathogen P. cristata. In addition to this work, PCR primers have been developed for the specific detection of the downy mildew pathogen in Tasmania.
Histology of Sclerotium cepivorum infection of onion roots and the spatial relationships of pectinases in the infection process
Publisher: Wiley
Date: 08-1999
Quantitative proteomics provides an insight into germination‐related proteins in the obligate biotrophic plant pathogen Spongospora subterranea
Publisher: Wiley
Date: 29-04-2021
Abstract: The soil‐borne and obligate plant‐associated nature of S . subterranea has hindered a detailed study of this pathogen and in particular, the regulatory pathways driving the germination of S . subterranea remain unknown. To better understand the mechanisms that control the transition from dormancy to germination, protein profiles between dormant and germination stimulant‐treated resting spores were compared using label‐free quantitative proteomics. Among the ~680 proteins identified 20 proteins were found to be differentially expressed during the germination of S . subterranea resting spores. Elongation factor Tu, histones (H2A and H15), proteasome and DJ‐1_PfpI, involved in transcription and translation, were upregulated during the germination of resting spores. Downregulation of both actin and beta‐tubulin proteins occurred in the germinating spores, indicating that the changes in the cell wall cytoskeleton may be necessary for the morphological changes during the germination of the resting spore in S . subterranea . Our findings provide new approaches for the study of these and similar recalcitrant micro‐organisms provide the first insights into the basic protein components of S . subterranea spores. A better understanding of S . subterranea biology may lead to the development of novel approaches for the management of persistent soil inoculum.
Diseases of Pyrethrum in Tasmania: Challenges and Prospects for Management
Publisher: Scientific Societies
Date: 09-2008
Multiplex RT-PCR detection of three common viruses infecting orchids
Publisher: Springer Science and Business Media LLC
Date: 07-2014
DOI: 10.1007/S00705-014-2161-9
Abstract: A multiplex reverse transcription polymerase chain reaction (RT-PCR) assay was developed for simultaneous detection of three orchid viruses: cymbidium mosaic virus (CymMV), odontoglossum ringspot virus (ORSV), and orchid fleck virus (OFV). Primers were used to lify nucleocapsid protein gene fragments of 845 bp (ORSV), 505 bp (CymMV) and 160 bp (OFV). A 60-bp licon of plant glyceraldehyde-3-phophate dehydrogenase mRNA was included as an internal control against false negatives. The assay was validated against 31 collected plants from six orchid genera and compared with results obtained by transmission electron microscopy (TEM). The RT-PCR assay proved more sensitive than TEM for detection of OFV.
Baseline sensitivity of Australian Phoma ligulicola isolates from pyrethrum to azoxystrobin and difenoconazole
Publisher: Wiley
Date: 24-04-2007
The process of antagonism of Sclerotium cepivorum in white rot affected onion roots by Trichoderma koningii
Publisher: Wiley
Date: 04-2001
Virus content of seed potato stocks produced in a unique seed potato production scheme
Publisher: Wiley
Date: 02-1990
Plant pathogens ? the great thieves of vegetable value
Publisher: International Society for Horticultural Science (ISHS)
Date: 09-2016
Host Range of Australian Phoma ligulicola var. inoxydablis Isolates from Pyrethrum
Publisher: Wiley
Date: 08-07-2008
DOI: 10.1111/J.1439-0434.2008.01401.X
Abstract: Ray blight, caused by Phoma ligulicola var. inoxydablis is one of the most damaging diseases of pyrethrum ( Tanacetum cinerariifolium [Trevir.] Sch. Bip.) in Australia. The pathogenicity of P. ligulicola var. inoxydablis to a range of ornamental and other plant species was tested to determine potential sources of inoculum into pyrethrum crops. Differences were identified in the host range of P. ligulicola var. inoxydablis isolates in this study in comparison with isolates reported from garden chrysanthemum ( Chrysanthemum morifolium L.), most likely to be P. ligulicola var. ligulicola . Australian P. ligulicola var. inoxydablis isolates were unable to infect and cause disease following repeated inoculation to zinnia ( Zinnia elegans L.), sunflower ( Helianthus annuus L.), dahlia ( Dahlia variabilis Desf.), and several cultivars of crisphead lettuce ( Lactuca sativa L.). French marigold ( Tagetes patula L.) was recorded as a susceptible host for this pathogen for the first time. Moreover, the susceptibility of annual chrysanthemum ( Chrysanthemum carinatum L.) to infection by P. ligulicola var. inoxydablis was confirmed. Implications for disease management in Tasmanian pyrethrum fields are discussed.
The effect of inoculum density of Sclerotium cepivorum on the ability of Trichoderma koningii to suppress White Rot of Onion
Publisher: Scientific Societies
Date: 03-2004
DOI: 10.1094/PDIS.2004.88.3.287
Abstract: Amendment of soil with Trichoderma koningii strain Tr5 grown on autoclaved white millet grain provided between 63 and 79% control of white rot of onion when added to soil containing 10, 25, 50, or 100 sclerotia of Sclerotium cepivorum per kilogram of soil at the time of onion seed sowing. There was no significant difference in the proportion of S. cepivorum infections suppressed among the different sclerotial density treatments. Rhizosphere colonization by T. koningii Tr5 was assessed by incubating onion roots s led from plants growing in soil with the appropriate density of sclerotia, on a Trichoderma selective medium (Rose bengall-Allisan-streptomycin-Previcur agar) developed for the purpose of the study. Trichoderma spp. isolated were typed by comparison of culture morphology as well as polygalacturonase (PG) (EC 3.2.1.15) and pectinesterase (PE) (EC 3.1.1.11) isozyme profiles to the series of one PG and two PE isozymes known to be produced by T. koningii Tr5. The method was used successfully to assess rhizosphere colonization. Three rates of a millet grain formulation colonized by T. koningii Tr5 were added to soil (1,590, 3,180, and 4,770 kg/ha). At the lowest of these rates, 97% of roots were found to be colonized by isolates which could not be distinguished from T. koningii Tr5, whereas 8% of the roots from nontreated controls were colonized by such isolates. An objective of the study was to determine whether the ability of T. koningii Tr5 to suppress S. cepivorum infections was influenced by increased concentrations of both S. cepivorum sclerotia and T. koningii Tr5-colonized millet grain, and it was found that no further improvements in the percentage of disease suppression were recorded as a result of adding T. koningii Tr5-colonized millet to the soil at more than 1,590 kg/ha at any of the sclerotium concentrations tested.
Resistance to infection and translocation of Tomato spotted wilt virus in potatoes
Publisher: Wiley
Date: 06-2001
Preliminary characterisation of bacteriophages of Serratia entomophila
Publisher: Wiley
Date: 04-1993
Colour preference and potato cultivar oviposition choice by onion thrips, Thrips tabaci (Thysanoptera: Thripidae)
Publisher: Elsevier BV
Date: 03-2019
Spatial Analysis of Viral Epidemics in Australian Hop Gardens: Implications for Mechanisms of Spread
Publisher: Scientific Societies
Date: 05-2000
DOI: 10.1094/PDIS.2000.84.5.513
Abstract: Plant-to-plant spread of Hop mosaic virus (HpMV), Hop latent virus (HpLV), and Prunus necrotic ringspot virus (PNRSV) were monitored in two commercial hop gardens of cv. Victoria in Australia. At site 1, the cultural practice of mowing to remove excess basal growth operated exclusively along rows, while at site 2, mowing occurred both along and across rows. Other cultural practices such as stringing, bine-training, spraying, and harvesting were directed along rows at both sites. Spatial aggregation within and across rows was assessed by ordinary runs analysis, and by radial correlation analysis using the program 2DCORR. The dominant spread mechanism of carlaviruses differed between sites. At site 1, along-row aggregation of both HpLV and HpMV in 1997 reflected the importance of basal-growth intertwining for virus transmission, either due to mechanical transmission or movement of apterous or alatae vectors along rows. At site 2, the random incidence of HpLV and HpMV reflected spread by alatae vectors. The spread of PNRSV at both sites was associated with mowing direction. This study reports the first use of a modified version of radial correlation analysis.
Evolution of the Genetic Structure of the Didymella tanaceti Population During Development of Succinate Dehydrogenase Inhibitor Resistance
Publisher: Scientific Societies
Date: 02-05-2023
Quantifying risk factors associated with light-induced potato tuber greening in retail stores
Publisher: Cold Spring Harbor Laboratory
Date: 18-06-2020
DOI: 10.1101/2020.06.18.158857
Abstract: Light conditions in retail stores may contribute to potato greening. In this study, we aimed to develop a potato tuber greening risk rating model for retail stores based on light quality and intensity parameters. This was achieved by firstly exposing three potato varieties (Nicola, Maranca and Kennebec) to seven specific light wavelengths (370, 420, 450, 530, 630, 660 and 735 nm) to determine the tuber greening propensity. Detailed light quality and intensity measurements from 25 retail stores were then combined with the greening propensity data to develop a tuber greening risk rating model. Our study showed that maximum greening occurred under blue light (450 nm), while 53%, 65% and 75% less occurred under green (530 nm), red (660 nm) and orange (630 nm) light, respectively. Greening risk, which varied between stores, was found to be related to light intensity level, and partially explained potato stock loss in stores. Our results from this study suggested that other in-store management practices, including lighting duration, average potato turnover, and light protection during non-retail periods, likely influence tuber greening risk.
Comparative assessment of genetic and epigenetic variation among regenerants of potato (Solanum tuberosum) derived from long-term nodal tissue-culture and cell selection
Publisher: Springer Science and Business Media LLC
Date: 06-01-2011
DOI: 10.1007/S00299-010-0983-9
Abstract: Three long-term nodal tissued cultured Russet Burbank potato clones and nine thaxtomin A-treated regenerant lines, derived from the nodal lines, were assessed for genetic and epigenetic (in the form of DNA methylation) differences by AFLP and MSAP. The treated regenerant lines were originally selected for superior resistance to common scab disease and acceptable tuber yield in pot and field trials. The long-term, tissue culture clone lines exhibited genetic (8.75-15.63% polymorphisms) and epigenetic (12.56-26.13% polymorphisms) differences between them and may represent a stress response induced by normal plant growth disruption. The thaxtomin A-treated regenerant lines exhibited much higher significant (p < 0.05) genetic (2-29.38%) and epigenetic (45.22-51.76%) polymorphisms than the nodal cultured parent clones. Methylation-sensitive mutations accumulated within the regenerant lines are significantly correlated (p < 0.05) to disease resistance. However, linking phenotypic differences that could be of benefit to potato growers, to single gene sequence polymorphisms in a tetraploid plant such as the potato would be extremely difficult since it is assumed many desirable traits are under polygenic control.
Tissue culture production of hazelnut ? disinfestation and impact of agar content
Publisher: International Society for Horticultural Science (ISHS)
Date: 02-2016
First Report of Cucumber Mosaic Cucumovirus on Wasabi in Australia
Publisher: Scientific Societies
Date: 05-1998
DOI: 10.1094/PDIS.1998.82.5.590A
Abstract: Wasabi (Wasabia japonica (Miquel) Matsum.), a native perennial of Japan and Shakhalin Island used to produce a condiment for Japanese dishes, is under commercial development in Tasmania, Australia. Plants propagated within shade houses showed systemic necrotic flecks and veinal necrosis in leaves and sunken necrotic stem lesions similar to those, reported in Japan (1), caused by cucumber mosaic cucumovirus (CMV). Necrosis progressed rapidly, resulting in death of plants transferred to or mechanically inoculated in a glasshouse (15 to 30°C) under full light. Disease progression in plants maintained in shade houses (5 to 20°C) was slower and symptoms less severe. Presence of CMV in symptomatic plants was confirmed by enzyme-linked immunosorbent assay (ELISA), using antiserum from Agdia (Elkhart, IN), and by sap transmission tests to healthy wasabi and Chenopodium quinoa plants. Incidence of CMV among plants in the shade houses was estimated at 10%. A survey of a commercial planting of 400 to 500 plants in November 1997, using ELISA, showed an incidence of 2.6% CMV-infected plants. They were concentrated at the field margins, suggesting that the inoculum originated from external sources rather than from transplants. This pathogen could have significant impact on the longevity and production of this crop in Australia. Reference: (1) S. Adachi. 1987. Wasabi cultivation. Shizuoka Pref. Agric. Exp. Sta. Pub., Shizuoka, Japan.
Diversity of the coat protein-coding region among Ilarvirus isolates infecting hop in Australia
Publisher: Wiley
Date: 10-2003
Dietary Microbial Toxins and Type 1 Diabetes
Publisher: Wiley
Date: 11-2003
Abstract: Toxins may promote type 1 diabetes by modifying or damaging the beta cell causing release of autoantigens. Streptomyces is a common soil bacterium that produces many toxic compounds. Some Streptomyces can infect vegetables, raising the possibility of dietary exposure to toxins. We aimed to identify toxins that erode cellular proton gradients in extracts of Streptomyces and infested vegetables and to establish the effect of low doses of these toxins on pancreatic islets in mice. The vacuolar ATPase inhibitors, bafilomycin and concanamycin, and the ionophore, nigericin, were identified in extracts from 4 of 13 Streptomyces isolated from infested potatoes and in potatoes themselves. Injection of bafilomycin A1 into mice impaired glucose tolerance, reduced islet size, and decreased relative beta cell mass. Thus, exposure to small quantities of bafilomycin in the diet may contribute to the cause of type 1 diabetes.
Impact of groundnut rosette disease on nutritive value and elemental composition of four varieties of peanut (Arachis hypogaea)
Publisher: Wiley
Date: 16-02-2016
DOI: 10.1111/AAB.12271
Mechanical transmission of Apple mosaic virus in Australian hop (Humulus lupulus) gardens
Publisher: Wiley
Date: 08-2002
Infection of Potato Tubers with the Common Scab Pathogen Streptomyces scabiei in a Soil-less System
Publisher: Wiley
Date: 02-11-2010
Key events in pathogenesis of spongospora diseases in potato: a review
Publisher: Springer Science and Business Media LLC
Date: 05-02-2016
Monitoring Spongospora subterranea development in potato roots reveals distinct infection patterns and enables efficient assessment of disease control methods
Publisher: Public Library of Science (PLoS)
Date: 09-09-2015
Stable and Extreme Resistance to Common Scab of Potato Obtained Through Somatic Cell Selection
Publisher: Scientific Societies
Date: 05-2010
Abstract: Somatic cell selection with thaxtomin A as a positive selection agent was used to isolate variants of potato cv. Russet Burbank with strong to extreme resistance to common scab. Glasshouse and field trials identified 51 variants with significantly reduced disease incidence (frequency of infected tubers) and severity (tuber lesion coverage) compared with the parent cultivar. The most promising variants exhibited extreme disease resistance, rarely showing lesions, which were invariably superficial and shallower than those on the parent. Resistance traits were consistently expressed both in 10 glasshouse and two field trials at different locations, with varied inoculum and disease pressure. Disease-resistant variants differed in their response to thaxtomin A in tuber slice bioassays. Of 23 variants tested, 10 showed reduced thaxtomin A susceptibility, with the remaining 13 responding similar to that of the parent. Thus, toxin tolerance was not the only factor responsible for observed disease resistance however, four of the five most disease-resistant variants had enhanced thaxtomin A tolerance, suggesting that this factor is important in the expression of strong disease resistance. Pathogenicity and toxin tolerance remained stable over a 6-year period, demonstrating that selected phenotypes were robust and genetic changes stable. The majority of disease-resistant variants had tuber yields equivalent to the parent cultivar in glasshouse trials. This suggests that selection for disease resistance was not associated with negative tuber attributes and that certain variants may have commercial merit, worthy of further agronomic testing.
Susceptibility of opium poppy and pyrethrum to root infection by Spongospora subterranea
Publisher: Wiley
Date: 13-07-2018
DOI: 10.1111/JPH.12746
Host Range of Australian Phoma ligulicola var. inoxydablis Isolates from Pyrethrum
Publisher: Wiley
Date: 08-07-2008
DOI: 10.1111/J.1439-0434.2008.01401.X
Abstract: Ray blight, caused by Phoma ligulicola var. inoxydablis is one of the most damaging diseases of pyrethrum ( Tanacetum cinerariifolium [Trevir.] Sch. Bip.) in Australia. The pathogenicity of P. ligulicola var. inoxydablis to a range of ornamental and other plant species was tested to determine potential sources of inoculum into pyrethrum crops. Differences were identified in the host range of P. ligulicola var. inoxydablis isolates in this study in comparison with isolates reported from garden chrysanthemum ( Chrysanthemum morifolium L.), most likely to be P. ligulicola var. ligulicola . Australian P. ligulicola var. inoxydablis isolates were unable to infect and cause disease following repeated inoculation to zinnia ( Zinnia elegans L.), sunflower ( Helianthus annuus L.), dahlia ( Dahlia variabilis Desf.), and several cultivars of crisphead lettuce ( Lactuca sativa L.). French marigold ( Tagetes patula L.) was recorded as a susceptible host for this pathogen for the first time. Moreover, the susceptibility of annual chrysanthemum ( Chrysanthemum carinatum L.) to infection by P. ligulicola var. inoxydablis was confirmed. Implications for disease management in Tasmanian pyrethrum fields are discussed.
The effect of irrigation strategies during tuber initiation on marketable yield and development of common scab disease of potato in Russet Burbank in Tasmania
Publisher: Springer Science and Business Media LLC
Date: 09-2001
DOI: 10.1007/BF02357902
The potential of reflective mulching in combination with insecticide sprays for control of aphid-borne viruses of iris and tulip in Tasmania
Publisher: Wiley
Date: 06-1999
Enzymatic Investigation of Spongospora subterranea Zoospore Attachment to Roots of Potato Cultivars Resistant or Susceptible to Powdery Scab Disease
Publisher: MDPI AG
Date: 09-02-2023
DOI: 10.3390/PROTEOMES11010007
Abstract: For potato crops, host resistance is currently the most effective and sustainable tool to manage diseases caused by the plasmodiophorid Spongospora subterranea. Arguably, zoospore root attachment is the most critical phase of infection however, the underlying mechanisms remain unknown. This study investigated the potential role of root-surface cell-wall polysaccharides and proteins in cultivars resistant/susceptible to zoospore attachment. We first compared the effects of enzymatic removal of root cell-wall proteins, N-linked glycans and polysaccharides on S. subterranea attachment. Subsequent analysis of peptides released by trypsin shaving (TS) of root segments identified 262 proteins that were differentially abundant between cultivars. These were enriched in root-surface-derived peptides but also included intracellular proteins, e.g., proteins associated with glutathione metabolism and lignin biosynthesis, which were more abundant in the resistant cultivar. Comparison with whole-root proteomic analysis of the same cultivars identified 226 proteins specific to the TS dataset, of which 188 were significantly different. Among these, the pathogen-defence-related cell-wall protein stem 28 kDa glycoprotein and two major latex proteins were significantly less abundant in the resistant cultivar. A further major latex protein was reduced in the resistant cultivar in both the TS and whole-root datasets. In contrast, three glutathione S-transferase proteins were more abundant in the resistant cultivar (TS-specific), while the protein glucan endo-1,3-beta-glucosidase was increased in both datasets. These results imply a particular role for major latex proteins and glucan endo-1,3-beta-glucosidase in regulating zoospore binding to potato roots and susceptibility to S. subterranea.
Somaclonal selection in potato for resistance to common scab provides concurrent resistance to powdery scab
Publisher: Wiley
Date: 18-10-2012
QPCR testing seed potato tubers for pathogens ? what value for potato seed certification?
Publisher: International Society for Horticultural Science (ISHS)
Date: 05-2016
Moments of weaknesses – exploiting vulnerabilities between germination and encystment in the Phytomyxea
Publisher: Wiley
Date: 06-04-2021
DOI: 10.1111/BRV.12717
Abstract: Attempts at management of diseases caused by protozoan plant parasitic Phytomyxea have often been ineffective. The dormant life stage is characterised by long‐lived highly robust resting spores that are largely impervious to chemical treatment and environmental stress. This review explores some life stage weaknesses and highlights possible control measures associated with resting spore germination and zoospore taxis. With phytomyxid pathogens of agricultural importance, zoospore release from resting spores is stimulated by plant root exudates. On germination, the zoospores are attracted to host roots by chemoattractant components of root exudates. Both the relatively metabolically inactive resting spore and motile zoospore need to sense the chemical environment to determine the suitability of these germination stimulants or attractants respectively, before they can initiate an appropriate response. Blocking such sensing could inhibit resting spore germination or zoospore taxis. Conversely, the short life span and the vulnerability of zoospores to the environment require them to infect their host within a few hours after release. Identifying a mechanism or conditions that could synchronise resting spore germination in the absence of host plants could lead to diminished pathogen populations in the field.
Visual and Radiometric Assessments for Yield Losses Caused by Ray Blight in Pyrethrum
Publisher: Wiley
Date: 2008
Comparative Proteomic Analysis of Potato Roots from Resistant and Susceptible Cultivars to Spongospora subterranea Zoospore Root Attachment In Vitro
Publisher: MDPI AG
Date: 15-09-2022
DOI: 10.3390/MOLECULES27186024
Abstract: Potato (Solanum tuberosum L.) exhibits broad variations in cultivar resistance to tuber and root infections by the soilborne, obligate biotrophic pathogen Spongospora subterranea. Host resistance has been recognised as an important approach in potato disease management, whereas zoospore root attachment has been identified as an effective indicator for the host resistance to Spongospora root infection. However, the mechanism of host resistance to zoospore root attachment is currently not well understood. To identify the potential basis for host resistance to S. subterranea at the molecular level, twelve potato cultivars differing in host resistance to zoospore root attachment were used for comparative proteomic analysis. In total, 3723 proteins were quantified from root s les across the twelve cultivars using a data-independent acquisition mass spectrometry approach. Statistical analysis identified 454 proteins that were significantly more abundant in the resistant cultivars 626 proteins were more abundant in the susceptible cultivars. In resistant cultivars, functional annotation of the proteomic data indicated that Gene Ontology terms related to the oxidative stress and metabolic processes were significantly over-represented. KEGG pathway analysis identified that the phenylpropanoid biosynthesis pathway was associated with the resistant cultivars, suggesting the potential role of lignin biosynthesis in the host resistance to S. subterranea. Several enzymes involved in pectin biosynthesis and remodelling, such as pectinesterase and pectin acetylesterase, were more abundant in the resistant cultivars. Further investigation of the potential role of root cell wall pectin revealed that the pectinase treatment of roots resulted in a significant reduction in zoospore root attachment in both resistant and susceptible cultivars. This study provides a comprehensive proteome-level overview of resistance to S. subterranea zoospore root attachment across twelve potato cultivars and has identified a potential role for cell wall pectin in regulating zoospore root attachment.
Relationship of resistance to common scab disease and tolerance to thaxtomin A toxicity within potato cultivars
Publisher: Springer Science and Business Media LLC
Date: 06-09-2019
Distribution and incidence of Carrot virus Y in Australia
Publisher: Springer Science and Business Media LLC
Date: 2004
DOI: 10.1071/AP03086
Resistance to phloem transport of potato leafroll virus in potato plants
Publisher: Microbiology Society
Date: 12-1992
DOI: 10.1099/0022-1317-73-12-3219
Abstract: A 'double-graft sandwich' technique in which sections of potato stem from different potato cultivars were grafted between a susceptible healthy stock plant and a potato leafroll virus (PLRV)-infected scion was used to study the rate of phloem transport of PLRV in cultivars differing in resistance to PLRV infection (IR) and accumulation (AR). Resistance to phloem transport (i.e. delayed PLRV systemic movement) was found in Bismark cultivar (IR A(S)). This was independent of IR and AR as the rate of movement in Bismark cultivar was markedly slower than that in Omega and Spunta (IR AR), Delaware (I(S) AR), and Desiree and Renova (I(S) A(S)) cultivars. It operated in Bismark cultivar stems of two different ages, but did not operate against potato virus X (PVX) and was not influenced by previous infection with this virus. Aphid vector (Myzus persicae) feeding preferences and colonization rates differed between cultivars, but the cultivar characteristics responsible were unrelated to IR, AR or resistance to phloem transport. Delayed systemic movement of PLRV out of leaves inoculated with viruliferous aphids was independent of AR and resistance to phloem transport, and remained unaffected by previous infection with PVX. It was also independent of cultivar factors causing different aphid feeding preferences and colonization rates, but may be linked to IR.
Adjustment of soil-surface pH and comparison with conventional fungicide treatments for control of lettuce drop Sclerotinia minor
Publisher: Wiley
Date: 06-2005
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