ORCID Profile
0000-0001-5021-1138
Current Organisation
University of Western Australia
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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)
Plant Biology | Plant Cell and Molecular Biology | Plant Physiology | Gene Expression | Protein Targeting And Signal Transduction | Plant Physiology | Plant Pathology | Tree improvement (incl. selection and breeding) | Forest biodiversity | Colloid And Surface Chemistry | Crop and Pasture Production | Genetics | Physical Chemistry (Incl. Structural) | Plant Biochemistry And Physiology | Forestry sciences | Plant Pathology | Ecosystem Function | Tree nutrition and physiology | Analytical Biochemistry | Cell Metabolism | Population And Ecological Genetics | Ecological Physiology
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Biological Sciences | Higher education | Biological sciences | Ornamentals, Australian natives and nursery plants | Grain legumes | Plant Production and Plant Primary Products not elsewhere classified | Essential Oil Crops (e.g. Tea Tree, Eucalyptus, Lavender, Peppermint, Boronia, Sandalwood) | Oilseeds | Field crops | Native forests | Wheat | Immune system and allergy | Control of pests and exotic species | Hardwood Plantations | Farmland, Arable Cropland and Permanent Cropland Soils | Primary plant products not elsewhere classified | Expanding Knowledge in the Environmental Sciences | Mining Flora, Fauna and Biodiversity | Flora, Fauna and Biodiversity at Regional or Larger Scales |
Related Links
Publications
Paenibacillus isolates possess diverse dextran-degrading enzymes
Publisher: Oxford University Press (OUP)
Date: 09-2004
Application of Trehalose and Salicylic Acid Mitigates Drought Stress in Sweet Basil and Improves Plant Growth
Publisher: MDPI AG
Date: 27-05-2021
Abstract: Trehalose (Tre) and salicylic acid (SA) are increasingly used to mitigate drought stress in crop plants. In this study, a pot experiment was performed to study the influence of Tre and SA applied in idually or in combination on the growth, photosynthesis, and antioxidant responses of sweet basil (Ocimum basilicum L.) exposed to drought stress. Basil plants were watered to 60% or 100% field capacity with or without treatment with 30 mM Tre and/or 1 mM SA. Drought negatively affected growth, physiological parameters, and antioxidant responses. Application of Tre and/or SA resulted in growth recovery, increased photosynthesis, and reduced oxidative stress. Application of Tre mitigated the detrimental effects of drought more than SA. Furthermore, co-application of Tre and SA largely eliminated the negative impact of drought by reducing oxidative stress through increased activities of antioxidant enzymes superoxide dismutase, peroxidase, and catalase, as well as the accumulation of the protective osmolytes proline and glycine betaine. Combined Tre and SA application improved water use efficiency and reduced the amount of malondialdehyde in drought-stressed plants. Our results suggested that combined application of Tre and SA may trigger defense mechanisms of sweet basil to better mitigate oxidative stress induced by drought stress, thereby improving plant growth.
Phosphorus nutrition of proteaceae in severely phosphorus-impoverished soils: Are there lessons to be learned for future crops?
Publisher: Oxford University Press (OUP)
Date: 15-04-2011
Arsenic toxicity: the effects on plant metabolism
Publisher: Frontiers Media SA
Date: 2012
Prokaryotic origins for the mitochondrial alternative oxidase and plastid terminal oxidase nuclear genes
Publisher: Wiley
Date: 19-11-2003
DOI: 10.1016/S0014-5793(03)01309-7
Abstract: The mitochondrial alternative oxidase is a diiron carboxylate quinol oxidase (Dox) found in plants and some fungi and protists, but not animals. The plastid terminal oxidase is distantly related to alternative oxidase and is most likely also a Dox protein. Database searches revealed that the alpha-proteobacterium Novosphingobium aromaticivorans and the cyanobacteria Nostoc sp. PCC7120, Synechococcus sp. WH8102 and Prochlorococcus marinus subsp. pastoris CCMP1378 each possess a Dox homolog. Each prokaryotic protein conforms to the current structural models of the Dox active site and phylogenetic analyses suggest that the eukaryotic Dox genes arose from an ancestral prokaryotic gene.
Isolation and sequence analysis of cDNAs encoding phospho enolpyruvate carboxykinase from the PCK-type C4 grass Urochloa panicoides
Publisher: Springer Science and Business Media LLC
Date: 1995
DOI: 10.1007/BF00020190
Antigibberellin-induced reduction of internode length favors in vitro flowering and seed-set in different pea genotypes
Publisher: Institute of Experimental Botany
Date: 03-2014
Disruption of ptLPD1 or ptLPD2, Genes That Encode Isoforms of the Plastidial Lipoamide Dehydrogenase, Confers Arsenate Hypersensitivity in Arabidopsis
Publisher: Oxford University Press (OUP)
Date: 20-05-2010
Abstract: Arsenic is a ubiquitous environmental poison that inhibits root elongation and seed germination to a variable extent depending on the plant species. To understand the molecular mechanisms of arsenic resistance, a genetic screen was developed to isolate arsenate overly sensitive (aos) mutants from an activation-tagged Arabidopsis (Arabidopsis thaliana) population. Three aos mutants were isolated, and the phenotype of each was demonstrated to be due to an identical disruption of plastidial LIPOAMIDE DEHYDROGENASE1 (ptLPD1), a gene that encodes one of the two E3 isoforms found in the plastidial pyruvate dehydrogenase complex. In the presence of arsenate, ptlpd1-1 plants exhibited reduced root and shoot growth and enhanced anthocyanin accumulation compared with wild-type plants. The ptlpd1-1 plants accumulated the same amount of arsenic as wild-type plants, indicating that the aos phenotype was not due to increased arsenate in the tissues but to an increase in the innate sensitivity to the poison. Interestingly, a ptlpd1-4 knockdown allele produced a partial aos phenotype. Two loss-of-function alleles of ptLPD2 in Arabidopsis also caused elevated arsenate sensitivity, but the sensitivity was less pronounced than for the ptlpd1 mutants. Moreover, both the ptlpd1 and ptlpd2 mutants were more sensitive to arsenite than wild-type plants, and the LPD activity in isolated chloroplasts from wild-type plants was sensitive to arsenite but not arsenate. These findings show that the ptLPD isoforms are critical in vivo determinants of arsenite-mediated arsenic sensitivity in Arabidopsis and possible strategic targets for increasing arsenic tolerance.
Development of DNA markers for hybrid identification in Leucadendron (proteaceae)
Publisher: Elsevier BV
Date: 08-2007
Physiological responses of habitat-forming seaweeds to increasing temperatures
Publisher: Wiley
Date: 08-2016
DOI: 10.1002/LNO.10362
A GmAOX2b antisense gene compromises vegetative growth and seed production in soybean
Publisher: Springer Science and Business Media LLC
Date: 04-02-2012
DOI: 10.1007/S00425-012-1601-6
Abstract: The alternative oxidase mediates the cyanide-resistant respiratory pathway in plant mitochondria. In non-thermogenic plants, the role of alternative oxidase in plant growth and development is not well understood. Soybean (Glycine max) lines carrying a GmAOX2b antisense gene had compromised vegetative growth and reproductive performance under typical glasshouse growth conditions. The reduction in vegetative growth was demonstrated by reduction in shoot height, the number of leaves per plant and the green leaf area. Antisense plants also had decreased pod formation and seed to pod ratios, which together led to a reduction in the number and total mass of seed produced. The negative effects of the antisense gene on pod set, seed set, ovule availability and total seed mass were primarily confined to the branches, rather than the main stem. The preferential effect of alternative oxidase suppression in the branches is discussed in relation to the reproductive potential of soybean under stress. Taken together, these results demonstrate that alternative oxidase provides the benefit of sustaining plant vegetative growth and reproductive capacity in soybean.
Comparative root colonisation of strawberry cultivars Camarosa and Festival by Fusarium oxysporum f. sp. fragariae
Publisher: Springer Science and Business Media LLC
Date: 28-03-2012
Analysis of the Alternative Oxidase Promoters from Soybean
Publisher: Oxford University Press (OUP)
Date: 11-2003
Abstract: Alternative oxidase (Aox) is a nuclear-encoded mitochondrial protein. In soybean (Glycine max), the three members of the gene family have been shown to be differentially expressed during normal plant development and in response to stresses. To examine the function of the Aox promoters, genomic fragments were obtained for all three soybean genes: Aox1, Aox2a, and Aox2b. The regions of these fragments immediately upstream of the coding regions were used to drive β-glucuronidase (GUS) expression during transient transformation of soybean suspension culture cells and stable transformation of Arabidopsis. The expression patterns of the GUS reporter genes in soybean cells were in agreement with the presence or absence of the various endogenous Aox proteins, determined by immunoblotting. Deletion of different portions of the upstream regions identified sequences responsible for both positive and negative regulation of Aox gene expression in soybean cells. Reporter gene analysis in Arabidopsis plants showed differential tissue expression patterns driven by the three upstream regions, similar to those reported for the endogenous proteins in soybean. The expression profiles of all five members of the Arabidopsis Aox gene family were examined also, to compare with GUS expression driven by the soybean upstream fragments. Even though the promoter activity of the upstream fragments from soybean Aox2a and Aox2b displayed the same tissue specificity in Arabidopsis as they do in soybean, the most prominently expressed endogenous genes in all tissues of Arabidopsis were of the Aox1 type. Thus although regulation of Aox expression generally appears to involve the same signals in different species, different orthologs of Aox may respond variously to these signals. A comparison of upstream sequences between soybean Aox genes and similarly expressed Arabidopsis Aox genes identified common motifs.
Diverse dextranase genes from Paenibacillus species
Publisher: Springer Science and Business Media LLC
Date: 12-01-2005
DOI: 10.1007/S00203-004-0756-3
Abstract: Genes encoding dextranolytic enzymes were isolated from Paenibacillus strains Dex40-8 and Dex50-2. Single, similar but non-identical dex1 genes were isolated from each strain, and a more ergent dex2 gene was isolated from strain Dex50-2. The protein deduced from the Dex40-8 dex1 gene sequence had 716 amino acids, with a predicted M(r) of 80.8 kDa. The proteins deduced from the Dex50-2 dex1 and dex2 gene sequences had 905 and 596 amino acids, with predicted M(r) of 100.1 kDa and 68.3 kDa, respectively. The deduced amino acid sequences of all three dextranolytic proteins had similarity to family 66 glycosyl hydrolases and were predicted to possess cleavable N-terminal signal peptides. Homology searches suggest that the Dex40-8 and Dex50-2 Dex1 proteins have one and two copies, respectively, of a carbohydrate-binding module similar to CBM_4_9 (pfam02018.11). The Dex50-2 Dex2 deduced amino acid sequence had highest sequence similarity to thermotolerant dextranases from thermophilic Paenibacillus strains, while the Dex40-8 and Dex50-2 Dex1 deduced protein sequences formed a distinct sequence clade among the family 66 proteins. Examination of seven Paenibacillus strains, using a polymerase chain reaction-based assay, indicated that multiple family 66 genes are common within this genus. The three recombinant proteins expressed in Escherichia coli possessed dextranolytic activity and were able to convert ethanol-insoluble blue dextran into an ethanol-soluble product, indicating they are endodextranases (EC 3.2.1.11). The reaction catalysed by each enzyme had a distinct temperature and pH dependence.
The contrasting leaf functional traits between a karst forest and a nearby non-karst forest in south-west China
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/FP19103
Abstract: Karst and non-karst forests occur in the same region in south-west China, but the soil water and mineral nutrients availability are different between the forests. Our hypothesis was that the leaves of karst trees would be better adapted to dry, nutrient-poor conditions than those of trees in a nearby non-karst forest. We compared the gas exchange, anatomical characteristics and mineral nutrient concentrations in leaves from 21 tree species in a tropical karst forest and 19 species in a nearby non-karst forest in south-west China. We found that the leaves of karst trees had higher P concentrations, photosynthetic capacity and water use efficiency, and greater adaxial and abaxial epidermis thickness than leaves of non-karst forest trees. Evergreen and deciduous trees differed more significantly in leaf functional traits in the karst forest than in the non-karst forest. The leaf palisade:spongy mesophyll thickness ratio was positively correlated with stomatal conductance and negatively correlated with photosynthetic water use efficiency in the karst forest but not in the non-karst forest. Our findings indicate that karst forest trees are more conservative in water use, whereas soil P deficiency could be a major limiting factor for the growth of non-karst forest trees.
Nitrate-uptake restraint in Banksia spp. (Proteaceae) and Melaleuca spp. (Myrtaceae) from a severely phosphorus-impoverished environment
Publisher: Springer Science and Business Media LLC
Date: 20-05-2022
DOI: 10.1007/S11104-022-05477-3
Abstract: South-western Australia has some of the most phosphorus (P)-impoverished soils in the world. Hakea prostrata (Proteaceae) has nitrate (NO 3 − )-uptake restraint, associated with its high P-use efficiency. This research explores how common this trait is in other Proteaceae and in co-occurring plant species in south-western Australia. Banksia attenuata (Proteaceae), B. telmatiaea (Proteaceae), Melaleuca seriata (Myrtaceae) and M. rhaphiophylla (Myrtaceae) were grown with no NO 3 − , Medium (500 µM) NO 3 − or High (2500 µM) NO 3 − treatments with no other source of nitrogen (N). Plants were harvested after treatments. Leaf nitrate and phosphate concentrations were determined, as well as biomass, total N and total P concentrations of leaves, stems and roots separately. Banksia attenuata , B. telmatiaea and M. seriata had similar total N content when supplied with High NO 3 − as they did when supplied with Medium NO 3 − . All four species had the same low leaf NO 3 − -N concentration in High and Medium NO 3 − treatments, no more than 6% of leaf total N. All species had similar leaf NO 3 − concentrations as those of plants growing in their natural habitat where the available soil nitrate concentration was much lower. These results are in sharp contrast with plants that are typically studied, for ex le Arabidopsis thaliana . All four species exhibited NO 3 − -uptake restraint to different degrees. Nitrate-uptake restraint appears a convergent trait common to many species that evolved in severely P-impoverished landscapes, allowing them to be more P-efficient.
The mature AEP2 gene product of Saccharomyces cerevisiae, required for the expression of subunit 9 of ATP synthase, is a 58 kDa mitochondrial protein
Publisher: Wiley
Date: 24-07-1995
DOI: 10.1016/0014-5793(95)00727-Q
Abstract: The nucleotide sequence of the yeast nuclear AEP2 gene, required for the expression of the mitochondrial DNA-encoded subunit 9 of ATP synthase, predicts a primary translation product of 67.5 kDa. The ATP13 gene is allelic to AEP2 but was reported to encode a protein of about 42 kDa in size. We thus investigated genetically and biochemically the size of the AEP2 gene product. Genetic complementation assays using 3' truncated AEP2 genes, here shows that function is abolished by the removal of only 32 amino acids from the C-terminus of the predicted protein product. Cell-free translation of AEP2 produces a 64 kDa polypeptide (consistent with the AEP2 sequence) which is imported into mitochondria and processed to a 58 kDa product by the removal of a presequence of about 50 amino acids.
Delineation of Sclerotinia sclerotiorum pathotypes using differential resistance responses on Brassica napus and B. juncea genotypes enables identification of resistance to prevailing pathotypes
Publisher: Elsevier BV
Date: 02-2012
The metabolic acclimation of Arabidopsis thaliana to arsenate is sensitized by the loss of mitochondrial LIPOAMIDE DEHYDROGENASE2, a key enzyme in oxidative metabolism
Publisher: Wiley
Date: 11-11-2014
DOI: 10.1111/PCE.12187
Abstract: Mitochondrial lipoamide dehydrogenase is essential for the activity of four mitochondrial enzyme complexes central to oxidative metabolism. The reduction in protein amount and enzyme activity caused by disruption of mitochondrial LIPOAMIDE DEHYDROGENASE2 enhanced the arsenic sensitivity of Arabidopsis thaliana. Both arsenate and arsenite inhibited root elongation, decreased seedling size and increased anthocyanin production more profoundly in knockout mutants than in wild-type seedlings. Arsenate also stimulated lateral root formation in the mutants. The activity of lipoamide dehydrogenase in isolated mitochondria was sensitive to arsenite, but not arsenate, indicating that arsenite could be the mediator of the observed phenotypes. Steady-state metabolite abundances were only mildly affected by mutation of mitochondrial LIPOAMIDE DEHYDROGENASE2. In contrast, arsenate induced the remodelling of metabolite pools associated with oxidative metabolism in wild-type seedlings, an effect that was enhanced in the mutant, especially around the enzyme complexes containing mitochondrial lipoamide dehydrogenase. These results indicate that mitochondrial lipoamide dehydrogenase is an important protein for determining the sensitivity of oxidative metabolism to arsenate in Arabidopsis.
Ex situ seed baiting to isolate germination-enhancing fungi for assisted colonization in Paphiopedilum spicerianum, a critically endangered orchid in China
Publisher: Elsevier BV
Date: 09-2020
Sugar and dihydroxyacetone ratios in floral nectar suggest continuous exudation and reabsorption in Leptospermum polygalifolium Salisb
Publisher: Elsevier BV
Date: 10-2022
DOI: 10.1016/J.PLANTSCI.2022.111378
Abstract: Leptospermum polygalifolium Salisb. can accumulate high concentrations of dihydroxyacetone (DHA), precursor of the antimicrobial compound methylglyoxal found in honey obtained from floral nectar of Leptospermum spp. Floral nectar dynamics over flower lifespan depends on internal and external factors that invariably impact nectar quality. Current models to estimate nectar quality in Leptospermum spp. overlook time of day, daily (24 h), and long-term dynamics of nectar exudation and accumulation over flower lifespan. To explain the dynamics of nectar quality over flower lifespan, accumulated nectar from flowers of different ages was collected from two L. polygalifolium clones, and then re-collected 24 h later from the same flowers. High-Performance Liquid Chromatography was used to quantify DHA amount and total equivalents of glucose + fructose (Tsugar) per flower in the nectar. DHA and Tsugar amount per flower differed with flower age and between clones. In accumulated nectar, the amount of DHA and Tsugar per flower rose to a broad peak post-anthesis before decreasing. Immediately after peaking DHA declined more quickly than Tsugar in accumulated nectar due to a greater decrease in the exudation of DHA than for Tsugar. The DHA : Tsugar ratios in accumulated nectar and in nectar exuded over the next 24 h were similar and decreased with flower age, indicating that exudation and reabsorption occurred concomitantly across flower development. Hence there is a balance between exudation and reabsorption. A quantitative model suggested that flowers have the potential to exude more DHA and Tsugar than actually accumulated.
New sources of resistance to Sclerotinia sclerotiorum for crucifer crops
Publisher: Elsevier BV
Date: 12-2013
Acclimation responses of Arabidopsis thaliana to sustained phosphite treatments
Publisher: Oxford University Press (OUP)
Date: 11-02-2013
DOI: 10.1093/JXB/ERT037
Phosphoenolpyruvate carboxykinase in the C4 monocot Urochloa panicoides is encoded by four differentially expressed genes
Publisher: Oxford University Press (OUP)
Date: 08-1999
Abstract: Previous screening of a cDNA library of leaf poly(A+) RNA from Urochloa panicoides, a phosphoenolpyruvate carboxykinase (PCK)-type C4 monocot, led to the characterization of cDNAs encoding the U. panicoides PCK subunit PCK1. A second PCK sequence, designated PCK2, has now been found by rescreening the library. The deduced PCK2 polypeptide is 626 residues in length, has a predicted molecular mass of 68,686 D, and is 96% identical to the deduced PCK1 sequence. Isolation and characterization of genomic DNA fragments revealed that the PCK1 and PCK2genes are each closely linked to another PCK gene. These additional genes have been designated PCK3 andPCK4, respectively. In each case, the second gene is located upstream and in the same transcriptional orientation as the gene characterized through cDNA analysis. A reverse transcription-polymerase chain reaction assay was used to demonstrate that PCK1 and PCK2 transcripts predominate in leaves, whereas PCK3 andPCK4 transcripts predominate in roots. Moreover, accumulation of PCK1 and PCK2 transcripts is light dependent. Direct N-terminal sequencing of PCK polypeptides purified from leaves demonstrated that PCK2 is produced. These results strongly suggest that PCK1 and PCK2 are involved in the photosynthetic CO2-concentrating mechanism active in U. panicoides.
Effects of water stress on respiration in soybean leaves
Publisher: Oxford University Press (OUP)
Date: 26-08-2005
Abstract: The effect of water stress on respiration and mitochondrial electron transport has been studied in soybean (Glycine max) leaves, using the oxygen-isotope-fractionation technique. Treatments with three levels of water stress were applied by irrigation to replace 100%, 50%, and 0% of daily water use by transpiration. The levels of water stress were characterized in terms of light-saturated stomatal conductance (gs): well irrigated (gs & 0.2 mol H2O m−2 s−1), mildly water stressed (gs between 0.1 and 0.2 mol H2O m−2 s−1), and severely water stressed (gs & 0.1 mol H2O m−2 s−1). Although net photosynthesis decreased by 40% and 70% under mild and severe water stress, respectively, the total respiratory oxygen uptake (Vt) was not significantly different at any water-stress level. However, severe water stress caused a significant shift of electrons from the cytochrome to the alternative pathway. The electron partitioning through the alternative pathway increased from 10% to 12% under well-watered or mild water-stress conditions to near 40% under severe water stress. Consequently, the calculated rate of mitochondrial ATP synthesis decreased by 32% under severe water stress. Unlike many other stresses, water stress did not affect the levels of mitochondrial alternative oxidase protein. This suggests a biochemical regulation (other than protein synthesis) that causes this mitochondrial electron shift.
Mechanisms underlying enhanced Cd translocation and tolerance in roots of Populus euramericana in response to nitrogen fertilization
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.PLANTSCI.2019.110206
Abstract: A pot experiment was conducted to evaluate how nitrogen (N) availability influences cadmium (Cd) absorption, translocation and stress tolerance in roots of Populus euramericana. Seedling growth was sensitive to N deficiency, but it was unaltered by Cd exposure. Cadmium absorption by roots was promoted by N deficiency, resulting in a higher root Cd concentration compared to the N-sufficient condition. Fine-root length was tightly correlated (R
Comparison of Soaking Corms with Moringa Leaf Extract Alone or in Combination with Synthetic Plant Growth Regulators on the Growth, Physiology and Vase Life of Sword Lily
Publisher: MDPI AG
Date: 17-11-2020
Abstract: Gladiolus is in demand worldwide as a cut-flower or landscaping plant, because of its superior commercial and ornamental value. Application of plant-based biostimulants has gained interest in the horticulture industry as an innovative and promising approach to ensure enhanced and sustainable yields along with better product quality. The influence of pre-plant corm soaks supplemented to 5% (v/v) with an aqueous extract from Moringa oleifera leaves (MLE) either alone or in combination with 50 mg/L salicylic acid (SA) or 50 mg/L gibberellic acid (GA) on the vegetative, physiological, and ornamental characteristics of potted gladiolus (Gladiolus grandiflorus) was investigated. In general, the treatment order for greatest horticultural value for all the parameters examined was: MLE + SA + GA MLE + GA or SA in idually MLE alone water-only control. Compared to other treatments, corms soaked in MLE + SA + GA had the earliest sprout time (3.7 days earlier than control), shortest production time (11 days earlier than control), tallest plant (159.5 cm), greatest number of leaves per plant (8.85 leaves), greatest maximum leaf area (66 cm2), highest SPAD reading (112) and photosynthetic activity (6.7 mmol m−2 s−1), longest spike length (91 cm), greatest number of florets per spike (20 florets), longest vase life (14.8 days), greatest N (1.53%), P (0.28%), and K (0.64%) concentrations, and largest corm diameter (4.68 cm) and mass (22.25 g). The highest total protein and proline concentrations were observed with the combined application of MLE + GA + SA. Our findings suggested that MLE either alone or in combination with other plant growth regulators not only increased the yield and quality of cut spikes, but also prolonged the vase life of cut gladiolus.
Facilitation of phosphorus acquisition by Banksia attenuata allows Adenanthos cygnorum (Proteaceae) to extend its range into severely phosphorus-impoverished habitats
Publisher: Springer Science and Business Media LLC
Date: 21-02-2023
DOI: 10.1007/S11104-023-05935-6
Abstract: In extremely low-phosphorus (P) environments, most Proteaceae exude carboxylates from cluster roots. These carboxylates mobilise inorganic P which leads to a relatively high leaf manganese concentration ([Mn]). However, we found that Adenanthos cygnorum (Proteaceae) in a low-P habitat did not invariably have a high leaf [Mn] in south-western Australia. We aimed to explore how A. cygnorum acquires P in severely P-impoverished habitats. We determined soil P concentrations and leaf [Mn] of A. cygnorum growing within 1 m and more than 10 m away from other large Proteaceae. We also grew plants in a glasshouse to determine its root carboxylate exudation and rhizosheath phosphatase activity. Adenanthos cygnorum did not produce functional cluster roots. It depended on carboxylates released by a P-mobilising neighbour, Banksia attenuata (Proteaceae), to acquire P when growing in severely P-impoverished soil ( 8 mg P kg − 1 dry soil). In slightly less P-impoverished soil ( 11 mg P kg − 1 dry soil), phosphatases released by A. cygnorum hydrolysed sufficient organic P that was relatively mobile. The reliance on facilitation of P acquisition in A cygnorum depended strongly on location. We demonstrated the exudation of phosphatases, which mobilise inorganic P this P was adequate for growth when there was sufficient organic P in soil. Facilitation of P acquisition by B. attenuata allowed A. cygnorum to extend its range into severely P-impoverished habitats where it cannot exist without facilitation. This knowledge provides a better understanding of the ersity of P-acquisition strategies in severely P-impoverished environments.
First Report of Neofusicoccum parvum Causing Leaf Spot Disease on Macadamia integrifolia in China
Publisher: Scientific Societies
Date: 02-2023
Isolation and characterization of genes encoding thermoactive and thermostable dextranases from two thermotolerant soil bacteria
Publisher: Springer Science and Business Media LLC
Date: 11-2004
DOI: 10.1007/S00284-004-4308-5
Abstract: Thermotolerant Paenibacillus strain Dex70-1B and unidentified strain Dex70-34 produce thermoactive dextran-degrading enzymes. Plasmid-based genomic DNA libraries constructed from mixed bacterial cultures containing Dex70-1B or Dex70-34 were screened for the ability to confer dextranolytic activity at 70 degrees C onto Escherichia coli. One gene, designated dex1, was isolated from each strain. The Dex70-1B and Dex70-34 dex1 gene sequences were non-identical, and encoded proteins containing 597 (M(r) 68.6 kDa) and 600 amino acids (M(r) 69.2 kDa), respectively. The Dex1 amino acid sequences were most similar to one another, and formed a new clade among the family 66 glycosyl hydrolase sequences. Expression of the Dex1 proteins in E. coli produced dextranolytic activity that converted ethanol-insoluble blue dextran into an ethanol-soluble form, suggestive of endodextranases (EC 3.2.1.11). Both enzymes were most active at about 60 degrees C and pH 5.5, and retained more than 70% maximal activity after incubation at 57 degrees C for 9.5 h in the absence of substrate.
An alternative oxidase monoclonal antibody recognises a highly conserved sequence among alternative oxidase subunits
Publisher: Wiley
Date: 19-03-1999
DOI: 10.1016/S0014-5793(99)00259-8
Abstract: The alternative oxidase is found in the inner mitochondrial membranes of plants and some fungi and protists. A monoclonal antibody raised against the alternative oxidase from the aroid lily Sauromatum guttatum has been used extensively to detect the enzyme in these organisms. Using an immunoblotting strategy, the antibody binding site has been localised to the sequence RADEAHHRDVNH within the soybean alternative oxidase 2 protein. Examination of sequence variants showed that A2 and residues C-terminal to H7 are required for recognition by the monoclonal antibody raised against the alternative oxidase. The recognition sequence is highly conserved among all alternative oxidase proteins and is absolutely conserved in 12 of 14 higher plant sequences, suggesting that this antibody will continue to be extremely useful in studying the expression and synthesis of the alternative oxidase.
First Report of Phytopythium vexans Causing Root Rot on Macadamia integrifolia in China
Publisher: Scientific Societies
Date: 09-2023
Opportunities for improving phosphorus-use efficiency in crop plants
Publisher: Wiley
Date: 12-06-2012
DOI: 10.1111/J.1469-8137.2012.04190.X
Abstract: Limitation of grain crop productivity by phosphorus (P) is widespread and will probably increase in the future. Enhanced P efficiency can be achieved by improved uptake of phosphate from soil (P‐acquisition efficiency) and by improved productivity per unit P taken up (P‐use efficiency). This review focuses on improved P‐use efficiency, which can be achieved by plants that have overall lower P concentrations, and by optimal distribution and redistribution of P in the plant allowing maximum growth and biomass allocation to harvestable plant parts. Significant decreases in plant P pools may be possible, for ex le, through reductions of superfluous ribosomal RNA and replacement of phospholipids by sulfolipids and galactolipids. Improvements in P distribution within the plant may be possible by increased remobilization from tissues that no longer need it (e.g. senescing leaves) and reduced partitioning of P to developing grains. Such changes would prolong and enhance the productive use of P in photosynthesis and have nutritional and environmental benefits. Research considering physiological, metabolic, molecular biological, genetic and phylogenetic aspects of P‐use efficiency is urgently needed to allow significant progress to be made in our understanding of this complex trait. Contents Summary 306 I. The need to use phosphorus efficiently 307 II. P‐use efficiency and P dynamics in a growing crop 307 III. P pools in plants 307 IV. Phosphorus pools and growth rates 310 V. Are crops different from other plants in their P concentration? 310 VI. Phosphorus use and photosynthesis 311 VII. Crop development and canopy P distribution 312 VIII. Internal redistribution of P in a growing vegetative plant 313 IX. Allocation of P to reproductive structures 314 X. Constraints to P remobilisation 315 XI. Do physiological or phylogenetic trade‐offs constrain traits that could improve PUE? 316 XII. Identifying genetic loci associated with PUE 316 XIII. Conclusions 317 Acknowledgements 317 References 317
A novel plant-fungus symbiosis benefits the host without forming mycorrhizal structures
Publisher: Wiley
Date: 27-11-2014
DOI: 10.1111/NPH.12600
Abstract: Most terrestrial plants form mutually beneficial symbioses with specific soil‐borne fungi known as mycorrhiza. In a typical mycorrhizal association, fungal hyphae colonize plant roots, explore the soil beyond the rhizosphere and provide host plants with nutrients that might be chemically or physically inaccessible to root systems. Here, we combined nutritional, radioisotopic ( 33 P) and genetic approaches to describe a plant growth promoting symbiosis between the basidiomycete fungus Austroboletus occidentalis and jarrah ( Eucalyptus marginata ), which has quite different characteristics. We show that the fungal partner does not colonize plant roots hyphae are localized to the rhizosphere soil and vicinity and consequently do not transfer nutrients located beyond the rhizosphere. Transcript profiling of two high‐affinity phosphate (Pi) transporter genes ( Em PHT 1 and Em PHT 1 ) and hyphal‐mediated 33 Pi uptake suggest that the Pi uptake shifts from an epidermal to a hyphal pathway in ectomycorrhizal plants ( Scleroderma sp.), similar to arbuscular mycorrhizal symbioses, whereas A. occidentalis benefits its host indirectly. The enhanced rhizosphere carboxylates are linked to growth and nutritional benefits in the novel symbiosis. This work is a starting point for detailed mechanistic studies on other basidiomycete–woody plant relationships, where a continuum between heterotrophic rhizosphere fungi and plant beneficial symbioses is likely to exist.
Responses of foliar phosphorus fractions to soil age are diverse along a 2 Myr dune chronosequence
Publisher: Wiley
Date: 26-06-2019
DOI: 10.1111/NPH.15910
Abstract: Plants respond to soil phosphorus (P) availability by adjusting leaf P among inorganic P (Pi) and organic P fractions (nucleic acids, phospholipids, small metabolites and a residual fraction). We tested whether phylogenetically ergent plants in a bio ersity hotspot similarly adjust leaf P allocation in response to P limitation by s ling along a 2 Myr chronosequence in southwestern Australia where nitrogen (N) limitation transitions to P limitation with increasing soil age. Total P and N, and P allocated to five chemical fractions were determined for photosynthetic organs from Melaleuca systena (Myrtaceae), Acacia rostellifera (Fabaceae) and Hakea prostrata (Proteaceae). Soil characteristics were also determined. Acacia rostellifera maintained phyllode total P and N concentrations at c . 0.5 and 16 mg g −1 DW, respectively, with a constant P‐allocation pattern along the chronosequence. H. prostrata leaves allocated less P to Pi, phospholipids and nucleic acids with increasing soil age, while leaf N concentration was constant. M. systena had the greatest variation in allocating leaf P, whereas leaf N concentration decreased 20% along the chronosequence. Variation in P‐allocation patterns was only partially conserved among species along the chronosequence. Such variation could have an impact on species distribution and contribute to species richness in P‐limited environments.
Adding Castanopsis hystrix to a Pinus massoniana plantation changed leaf phosphorus and nitrogen investment and soil nitrogen concentrations
Publisher: Springer Science and Business Media LLC
Date: 26-06-2023
Phosphorus fractions in leaves
Publisher: Wiley
Date: 02-12-2023
DOI: 10.1111/NPH.18588
Abstract: Leaf phosphorus (P) comprises four major fractions: inorganic phosphate (P i ), nucleic acids, phospholipids, P‐containing metabolites and a residual fraction. In this review paper, we investigated whether allocation of P fractions varies among groups of terrestrial vascular plants, and is indicative of a species' strategy to use P efficiently. We found that as leaf total P concentration increases, the P i fraction increases the most, without a plateau, while other fractions plateau. Variability of the concentrations of leaf P fractions is greatest among families species(family) regions plant life forms. The percentage of total P allocated to nucleic acid‐P (20–35%) and lipid‐P (14–34%) varies less among families/species. High photosynthetic P‐use efficiency is associated with low concentrations of all P fractions, and preferential allocation of P to metabolite‐P and mesophyll cells. Sequential resorption of P from senescing leaves starts with P i , followed by metabolite‐P, and then other organic P fractions. Allocation of P to leaf P fractions varies with season. Leaf phytate concentrations vary considerably among species, associated with variation in photosynthesis and defence. Plasticity of P allocation to its fractions is important for acclimation to low soil P availability, and species‐specific P allocation is needed for co‐occurrence with other species.
First Report of Phoma herbarum on Field Pea (Pisum sativum) in Australia
Publisher: Scientific Societies
Date: 12-2011
Abstract: Black spot disease on field pea (Pisum sativum) in Australia is generally caused by one or more of the four fungi: Mycosphaerella pinodes (anamorph Ascochyta pinodes), Phoma medicaginis var. pinodella (synonym Phoma pinodella), Ascochyta pisi, and Phoma koolunga (1,2,4). However, in 2010 from a field pea blackspot disease screening nursery at Medina, Western Australia, approximately 25% of isolates were a Phoma sp. that was morphologically different to Phoma spp. previously reported on field pea in Western Australia, while the remaining 75% of isolates were either M. pinodes or P. medicaginis var. pinodella. Single-spore isolations of 23 isolates of this Phoma sp. were made onto potato dextrose agar. A PCR-based assay with the TW81 and AB28 primers was used to lify from the 3′ end of 16S rDNA, across ITS1, 5.8S rDNA, and ITS2 to the 5′ end of the 28S rDNA. The DNA products were sequenced and BLAST analyses were used to compare sequences with those in GenBank. In each case, the sequence had ≥99% nucleotide identity with the corresponding sequence in GenBank for P. herbarum. Isolates also showed morphological similarities to P. herbarum as described in other reports (e.g., 3). The relevant information for a representative isolate has been lodged in GenBank (Accession No. JN247437). The same primers were used by Davidson et al. (2) to identify P. koolunga, but none of our 23 isolates were P. koolunga. A conidial suspension of 10 7 conidia ml –1 from a single-spore culture was spray inoculated onto foliage of 10-day-old Pisum sativum cv. Dundale plants maintained under % relative humidity conditions for 72 h postinoculation. Symptoms evident by 11 days postinoculation consisted of pale brown lesions that were mostly 1.5 to 2 mm long and 1 to 1.5 mm wide. Approximately 50% of lesions showed a distinct chlorotic halo extending 1 to 2 mm outside the boundary of the lesion. P. herbarum was readily reisolated from infected foliage. A culture of this representative isolate has been lodged in the Western Australian Culture Collection Herbarium maintained at the Department of Agriculture and Food Western Australia (Accession No. WAC13499). Outside of Australia, P. herbarum, while generally considered a soilborne opportunistic pathogen, has been reported on a wide range of species, including field pea (3). Molecular analysis of historical isolates collected from field pea in Western Australia, mostly in the late 1980s, did not show any incidence of P. herbarum, despite this fungus being reported on alfalfa (Medicago sativa) and soybean (Glycine max) in Western Australia in 1985 (Australian Plant Pest Database). In Western Australia, this fungus has also been recorded on a Protea sp. in 1991 and on Arabian pea (Bituminaria bituminosa) in 2010 (Australian Plant Pest Database). To our knowledge, this is the first report of P. herbarum as a pathogen on field pea in Australia. These previous reports of P. herbarum on other hosts in Western Australia and the wide host range of P. herbarum together suggest the potential for this fungus to be a pathogen on a wider range of genera/species than field pea. References: (1) T. W. Bretag and M. Ramsey. Page 24 in: Compendium of Pea Diseases and Pests. 2nd ed. The American Phytopathologic Society, St Paul, MN, 2001. (2) J. A. Davidson et al. Mycologica 101:120, 2009. (3) G. L. Kinsey. Phoma herbarum. No 1501. IMI Descriptions of Fungi and Bacteria, 2002. (4) T. L. Peever et al. Mycologia 99:59, 2007.
Mitochondrial protein expression in tomato fruit during on-vine ripening and cold storage
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/PP01245
Abstract: We have investigated the activity and abundance of a number of respiratory chain components in ripening and cold-treated tomato fruits (Lycopersicon esculentum L. Mill cvv. Moneymaker and Sweetie). Expression of the alternative oxidase (AOX) protein increased dramatically in both situations. Levels of the plant uncoupling protein (UCP) initially fell, but increased substantially in the later stages of ripening. In contrast, ATP synthase subunits and the COXII subunit of cytochrome oxidase decreased during ripening and increased slightly in response to cold stress. Other proteins involved in electron transport, tricarboxylic acid cycle function, chaperonin function, and membrane transport were also studied. These showed varying degrees of enhanced and depressed expression patterns. There were modest changes in whole fruit respiratory activities, and electron transport capacity of isolated mitochondria in response to these stimuli. However, respiratory control by ADP in the isolated mitochondria decreased as AOX capacity and abundance increased, indicating that although total respiration rates changed little, flux between the coupled and uncoupled pathways altered. The changes observed in AOX and UCP accumulation in tomato fruit that were vine-ripened were significantly different from post-harvest ripening patterns previously reported. The altered protein profiles are discussed in the context of on- and off-vine ripening and the potentially different roles of uncoupled respiration in each situation.
Leaf gas exchange and water relations of the woody desiccation-tolerant Paraboea rufescens during dehydration and rehydration
Publisher: Oxford University Press (OUP)
Date: 31-07-2022
Abstract: Desiccation-tolerant (DT) plants can withstand dehydration to less than 0.1 g H2O g−1 dry weight. The mechanism for whole-plant recovery from severe dehydration is still not clear, especially for woody DT plants. In the present study, we evaluated the desiccation tolerance and mechanism of recovery for a potentially new woody resurrection plant Paraboea rufescens (Gesneriaceae). We monitored the leaf water status, leaf gas exchange, chlorophyll fluorescence and root pressure of potted P. rufescens during dehydration and rehydration, and we investigated the water content and chlorophyll fluorescence of P. rufescens leaves in the field during the dry season. After re-watering from a severely dehydrated state, leaf maximum quantum yield of photosystem II of P. rufescens quickly recovered to well-watered levels. Leaf water status and leaf hydraulic conductance quickly recovered to well-watered levels after re-watering, while leaf gas exchange traits also trended to recovery, but at a slower rate. The maximum root pressure in rehydrated P. rufescens was more than twice in well-watered plants. Our study identified P. rufescens as a new DT woody plant. The whole-plant recovery of P. rufescens from extreme dehydration is potentially associated with an increase of root pressure after rehydration. These findings provide insights into the mechanisms of recovery of DT plants from dehydration.
Denaturing gradient gel electrophoresis analysis of the tissue nonspecific alkaline phosphatase isoenzyme gene in hypophosphatasia
Publisher: Elsevier BV
Date: 02-2002
Characterization of a yeast nuclear gene, AEP2, required for accumulation of mitochondrial mRNA encoding subunit 9 of the ATP synthase
Publisher: Springer Science and Business Media LLC
Date: 07-1991
DOI: 10.1007/BF00312765
Identification of a 66 KDa protein associated with yeast mitochondrial ATP synthase as heat shock protein hsp60
Publisher: Wiley
Date: 30-07-1990
DOI: 10.1016/0014-5793(90)81024-I
Abstract: A 66 kDa protein, denoted P66, not hitherto classified as an integral component of yeast mitochondrial ATPase, is often observed in preparations of this enzyme complex. A physical association exists between P66 and the assembled ATPase complex since both components are coimmunoprecipitated by anti-F1 beta monoclonal antibody. Two recombinant clones expressing proteins immunologically similar to P66 were isolated from a yeast genomic library in lambda gt11 by screening with a polyclonal anti-holo-ATPase antibody. Based on restriction site mapping and partial nucleotide sequence analysis, both clones encompass the gene encoding the yeast heat shock protein hsp60. The identification of P66 with hsp60, taken together with its demonstrated association with the mitochondrial ATPase complex, is consistent with recent suggestions that hsp60 is involved in assembly of the ATP synthase complex.
Tight control of nitrate acquisition in a plant species that evolved in an extremely phosphorus-impoverished environment
Publisher: Wiley
Date: 02-11-2016
DOI: 10.1111/PCE.12853
Abstract: Hakea prostrata (Proteaceae) has evolved in an extremely phosphorus (P)-limited environment. This species exhibits an exceptionally low ribosomal RNA (rRNA) and low protein and nitrogen (N) concentration in its leaves. Little is known about the N requirement of this species and its link to P metabolism, despite this being the key to understanding how it functions with a minimal P budget. H. prostrata plants were grown with various N supplies. Metabolite and elemental analyses were performed to determine its N requirement. H. prostrata maintained its organ N content and concentration at a set point, independent of a 25-fold difference nitrate supplies. This is in sharp contrast to plants that are typically studied, which take up and store excess nitrate. Plants grown without nitrate had lower leaf chlorophyll and carotenoid concentrations, indicating N deficiency. However, H. prostrata plants at low or high nitrate availability had the same photosynthetic pigment levels and hence were not physiologically compromised by the treatments. The tight control of nitrate acquisition in H. prostrata retains protein at a very low level, which results in a low demand for rRNA and P. We surmise that the constrained nitrate acquisition is an adaptation to severely P-impoverished soils.
Expression and kinetics of the mitochondrial alternative oxidase in nitrogen-fixing nodules of soybean roots
Publisher: Wiley
Date: 10-1997
Arabidopsis PHOSPHATE TRANSPORTER1 genes PHT1;8 and PHT1;9 are involved in root-to-shoot translocation of orthophosphate
Publisher: Springer Science and Business Media LLC
Date: 27-11-2014
Wide Variation in Virulence and Genetic Diversity of Binucleate Rhizoctonia Isolates Associated with Root Rot of Strawberry in Western Australia
Publisher: Public Library of Science (PLoS)
Date: 18-02-2010
Lipid Biosynthesis and Protein Concentration Respond Uniquely to Phosphate Supply during Leaf Development in Highly Phosphorus-Efficient Hakea prostrata
Publisher: Oxford University Press (OUP)
Date: 14-10-2014
Organ-specific phosphorus-allocation patterns and transcript profiles linked to phosphorus efficiency in two contrasting wheat genotypes
Publisher: Wiley
Date: 05-11-2014
DOI: 10.1111/PCE.12210
Abstract: Recent studies have identified genotypic variation in phosphorus (P) efficiency, but rarely have the underlying mechanisms been described at the molecular level. We demonstrate that the highly P-efficient wheat (Triticum aestivum L.) cultivar Chinese 80-55 maintains higher inorganic phosphate (Pi ) concentrations in all organs upon Pi withdrawal in combination with higher Pi acquisition in the presence of Pi when compared with the less-efficient cultivar Machete. These findings correlated with differential organ-specific expression of Pi transporters TaPHT1 , TaPHT1 , TaPHT1 , TaPHT2 and H(+) -ATPase TaHa1. Observed transcript level differences between the cultivars suggest that higher de novo phospholipid biosynthetic activities in Pi -limited elongating basal leaf sections are another crucial adaptation in Chinese 80-55 for sustaining growth upon Pi withdrawal. These activities may be supported through enhanced breakdown of starch in Chinese 80-55 stems as suggested by higher TaGPho1 transcript levels. Chinese 80-55 fine roots on the other hand show strong suppression of transcripts involved in glycolysis, transcriptional regulation and ribosomal activities. Our work reveals major differences in the way the two contrasting cultivars allocate Pi and organic P compounds between source and sink tissues and in the acclimation of their metabolism to changes in Pi availability.
Foliar Application of Trehalose or 5-Aminolevulinic Acid Improves Photosynthesis and Biomass Production in Drought Stressed Alpinia zerumbet
Publisher: MDPI AG
Date: 23-09-2021
DOI: 10.3390/AGRICULTURE11100908
Abstract: Alpinia zerumbet is an important medicinal and ornamental plant species. Drought stress is a major concern for sustainable horticulture crop production under changing climate scenarios. Trehalose (Tre) and 5-aminolevulinic acid (ALA) are osmoprotectants that play important roles in mitigating plant stresses. In this study, the effects of foliar application of 25 mM Tre or 10 mg L−1 ALA on biochemical and physiological parameters of A. zerumbet seedlings and their growth were evaluated under well-watered and drought-stressed (65% of field capacity) conditions. Drought caused reductions in physiological parameters and plant growth. These decreases were accompanied by increases in leaf free proline and glycine betaine concentrations and peroxidase activities. Foliar application of Tre or ALA remediated physiological and biochemical parameters and plant growth. Overall, foliar application of ALA or Tre proved to be beneficial for mitigating drought stress in A. zerumbet.
Strategies to acquire and use phosphorus in phosphorus-impoverished and fire-prone environments
Publisher: Springer Science and Business Media LLC
Date: 19-05-2022
DOI: 10.1007/S11104-022-05464-8
Abstract: Unveiling the ersity of plant strategies to acquire and use phosphorus (P) is crucial to understand factors promoting their coexistence in hyper erse P-impoverished communities within fire-prone landscapes such as in cerrado (South America), fynbos (South Africa) and kwongan (Australia). We explore the ersity of P-acquisition strategies, highlighting one that has received little attention: acquisition of P following fires that temporarily enrich soil with P. This strategy is expressed by fire ephemerals as well as fast-resprouting perennial shrubs. A plant’s leaf manganese concentration ([Mn]) provides significant clues on P-acquisition strategies. High leaf [Mn] indicates carboxylate-releasing P-acquisition strategies, but other exudates may play the same role as carboxylates in P acquisition. Intermediate leaf [Mn] suggests facilitation of P acquisition by P-mobilising neighbours, through release of carboxylates or functionally similar compounds. Very low leaf [Mn] indicates that carboxylates play no immediate role in P acquisition. Release of phosphatases also represents a P-mining strategy, mobilising organic P. Some species may express multiple strategies, depending on time since germination or since fire, or on position in the landscape. In severely P-impoverished landscapes, photosynthetic P-use efficiency converges among species. Efficient species exhibit rapid rates of photosynthesis at low leaf P concentrations. A high P-remobilisation efficiency from senescing organs is another way to use P efficiently, as is extended longevity of plant organs. Many P-acquisition strategies coexist in P-impoverished landscapes, but P-use strategies tend to converge. Common strategies of which we know little are those expressed by ephemeral or perennial species that are the first to respond after a fire. We surmise that carboxylate-releasing P-mobilising strategies are far more widespread than envisaged so far, and likely expressed by species that accumulate metals, exemplified by Mn, metalloids, such as selenium, fluorine, in the form of fluoroacetate, or silicon. Some carboxylate-releasing strategies are likely important to consider when restoring sites in bio erse regions as well as in cropping systems on P-impoverished or strongly P-sorbing soils, because some species may only be able to establish themselves next to neighbours that mobilise P.
Characterization of a second nuclear gene, AEP1, required for expression of the mitochondrial OLI1 gene in Saccharomyces cerevisiae
Publisher: Springer Science and Business Media LLC
Date: 07-1993
DOI: 10.1007/BF00324676
Seedling resistance to Sclerotinia sclerotiorum as expressed across diverse cruciferous species
Publisher: Scientific Societies
Date: 02-2013
DOI: 10.1094/PDIS-06-13-0612-RE
Abstract: Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is a serious disease of many cruciferous crops and frequently poses a threat to the sustainable and profitable production of these crops worldwide. Differences in seedling resistance to S. sclerotiorum across 46 erse cruciferous genotypes from 12 different species were assessed by comparing the extent of pathogenesis on inoculated cotyledons under controlled conditions. Selections of Brassica carinata, B. incana, B. juncea, B. napus, and B. napus introgressed with B. carinata, B. nigra, B. oleracea, B. rapa var. rosularis, B. rapa var. chinensis, B. tournefortii, Raphanus raphanistrum, R. sativus, and Sinapis arvensis were tested. The average size of lesions on cotyledons 48 h post inoculation varied from 0.8 to 7.3 mm. The three most resistant genotypes with the smallest lesions were all from B. oleracea (viz., B. oleracea var. italica ‘Prophet’ and B. oleracea var. capitata ‘Burton’ and ‘Beverly Hills’). Representatives of R. raphanistrum, S. arvensis, B. juncea, and B. carinata were the most susceptible to S. sclerotiorum, with the largest lesions. To our knowledge, this is the first report of high levels of resistance to S. sclerotiorum in B. oleracea at the cotyledon stage and also the first report of the host cotyledon reactions against S. sclerotiorum for all tested species except B. napus and B. juncea. The mean lesion size for B. napus introgressed with B. carinata was 5.6 mm, which is midway between the lesion size for the two parent species B. napus (5.1 mm) and B. carinata (5.8 mm). Separate genetic control for cotyledon versus mature plant resistance was demonstrated by the lack of correlation between lesion size from S. sclerotiorum on the cotyledon with the severity of disease initiated by stem inoculation or natural processes in a previous field test. On the most resistant genotypes, B. oleracea var. italica Prophet and var. capitata Burton, growth of S. sclerotiorum on the cotyledon surface prior to penetration was severely impeded, production of appressoria inhibited, and both cytoplasm shrinkage and protoplast extrusion in S. sclerotiorum hyphae prevalent. This is the first report of such resistant mechanisms in B. oleracea. Genotypes with cotyledon resistance identified in this study will be of great value not only in furthering our understanding of resistance mechanisms across different cruciferous species but also could be exploited for developing commercial crucifer cultivars with high-level resistance against S. sclerotiorum.
Approaches to increase the validity of gene family identification using manual homology search tools
Publisher: Springer Science and Business Media LLC
Date: 10-10-2023
Reproductive ecology of Paphiopedilum spicerianum
Publisher: Elsevier BV
Date: 09-2020
How Does Evolution in Phosphorus-Impoverished Landscapes Impact Plant Nitrogen and Sulfur Assimilation?
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.TPLANTS.2018.10.004
Abstract: Phosphorus (P) fertilisers, made from rock phosphate, are used to attain high crop yields. However, rock phosphate is a finite resource and excessive P fertilisers pollute our environment, stressing the need for more P-efficient crops. Some Proteaceae have evolved in extremely P-impoverished environments. One of their adaptations is to curtail the abundance of ribosomal RNA, and thus protein, and tightly control the acquisition and assimilation of nitrogen (N) and sulfur. This differs fundamentally from plants that evolved in environments where N limits plant productivity, but is likely common in many species that evolved in P-impoverished landscapes. Here, we scrutinise the relevance of these responses towards developing P-efficient crops, focusing on plant species where 'P is in the driver's seat'.
Sensitivity of jarrah (Eucalyptus marginata) to phosphate, phosphite, and arsenate pulses as influenced by fungal symbiotic associations
Publisher: Springer Science and Business Media LLC
Date: 26-01-0660
Differentiating phosphate-dependent and phosphate-independent systemic phosphate-starvation response networks in Arabidopsis thaliana through the application of phosphite
Publisher: Oxford University Press (OUP)
Date: 19-02-2015
DOI: 10.1093/JXB/ERV025
Dihydroxyacetone in the Floral Nectar of Ericomyrtus serpyllifolia (Turcz.) Rye (Myrtaceae) and Verticordia chrysantha Endl. (Myrtaceae) Demonstrates That This Precursor to Bioactive Honey Is Not Restricted to the Genus Leptospermum (Myrtaceae)
Publisher: American Chemical Society (ACS)
Date: 16-05-2023
Delayed leaf greening involves a major shift in the expression of cytosolic and mitochondrial ribosomes to plastid ribosomes in the highly phosphorus-use-efficient Hakea prostrata (Proteaceae)
Publisher: Springer Science and Business Media LLC
Date: 27-09-2023
Growth-climate relationships and long-term growth trends of the tropical forest tree choerospondias axillaris (Anacardiaceous) in east-central Thailand
Publisher: MDPI AG
Date: 29-11-2021
DOI: 10.3390/F12121655
Abstract: Tropical forests play important roles in global carbon cycling. Tree-ring analysis can provide important information for understanding long-term trends in carbon-fixation capacity under climate change. However, tree-ring studies in tropical regions are limited. We carried out a tree-ring analysis to investigate the dendrochronological potential of the tropical forest tree Choerospondias axillaris (Anacardiaceae) in east-central Thailand. Our study focused on growth-climate relationships and long-term growth trends. A chronology was constructed covering the period from 1932 to 2019. The tree-ring width index of C.axillaris was positively correlated with precipitation in June, July, and October. Furthermore, growth of C.axillaris was positively correlated with the Standardized Precipitation-Evapotranspiration Index (SPEI) from July to October, indicating that growth of C.axillaris is mainly limited by moisture availability in the late monsoon season. Moving correlation analysis further revealed the consistency and temporal stability of the relationship of tree growth with monsoon season precipitation and SPEI during the period under study. There was a significant increasing trend in long-term growth from 1932 to 2002 (slope = 0.017, p 0.001) however, long-term growth decreased from 2003 to 2019 (slope = −0.014, p 0.001). Our study provides important insight into the growth-climate correlations of a broad-leaved tree species in a dry evergreen forest in tropical Asia.
The alternative respiratory pathway mediates carboxylate synthesis in white lupin cluster roots under phosphorus deprivation
Publisher: Wiley
Date: 28-10-2014
DOI: 10.1111/PCE.12208
Abstract: Plant adaptations associated with a high efficiency of phosphorus (P) acquisition can be used to increase productivity and sustainability in a world with a growing population and decreasing rock phosphate reserves. White lupin (Lupinus albus) produces cluster roots that release carboxylates to efficiently mobilize P from P-sorbing soils. It has been hypothesized that an increase in the activity of the alternative oxidase (AOX) would allow for the mitochondrial oxidation of NAD(P)H produced during citrate synthesis in cluster roots at a developmental stage when there is a low demand for ATP. We used the oxygen-isotope fractionation technique to study the in vivo respiratory activities of the cytochrome oxidase pathway (COP) and the alternative oxidase pathway (AOP) in different root sections of white lupins grown hydroponically with and without P. In parallel, AOX protein levels and internal carboxylate concentrations were determined in cluster and non-cluster roots. Higher in vivo AOP activity was measured in cluster roots when malate and citrate concentrations were also high, thus confirming our hypothesis. AOX protein levels were not always correlated with in vivo AOP activity, suggesting post-translational regulation of AOX.
Dual mycorrhizal associations of jarrah (Eucalyptus marginata) in a nurse-pot system
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/BT12152
Abstract: Jarrah (Eucalyptus marginata Donn ex Sm.) plants, like many other eucalypts, can form symbiotic associations with both arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi. To study this tripartite relationship we developed a novel nurse-pot system to allow us to investigate the extent and temporal colonisation dynamics of jarrah by two AM species (Rhizophagus irregularis (Błaszk., Wubet, Renker & Buscot) C. Walker & A. Schüßler comb. nov. and Scutellospora calospora Nicol. & Gerd.) and two putative ECM species (Austroboletus occidentalis Watling & N.M. Greg. and Scleroderma sp.) and their potential effects on jarrah growth and nutrition. Our nurse-pot system, using jarrah as both the nurse plant and test plant, was developed to establish extraradical hyphal networks of both AM and ECM fungi that act as single or dual inoculum for test plants. Mycorrhizal colonisation was described and quantified, and growth and nutritional effects measured and analysed. Mycorrhizal colonisation increased with time for the test seedlings exposed to hyphae networks from S. calospora and Scleroderma sp. The nurse-pot system was effective at initiating colonisation of functioning AM or (putative) ECM systems separately but the ECM symbiosis was inhibited where a dual AM + ECM inoculum (R. irregularis and Scleroderma sp.) was present. The presence of S. calospora, A. occidentalis and Scleroderma sp. in idually significantly increased the shoot biomass of seedlings compared with non-mycorrhizal controls. The two AM isolates had different physiological effects on jarrah plants. S. calospora improved growth and micronutrient uptake of jarrah seedlings whereas no positive response was observed with R. irregularis. In addition, as an interesting observation, the non-responsive AM fungus R. irregularis suppressed the ECM symbiosis in dually inoculated plants where ECM structures, positive growth response and nutritional effects were absent. When inoculated in idually, ECM isolates dominated the growth response and uptake of P and other nutrients in this dual symbiotic plant. Despite the positive growth response in the A. occidentalis treatment, ECM structures were not observed in either nurse or test seedlings. From the effects of A. occidentalis on jarrah we hypothesise that this fungus forms a functional mycorrhizal-type partnership even without forming archetypal structures in and on the root.
Ecto- and arbuscular mycorrhizal symbiosis can induce tolerance to toxic pulses of phosphorus in jarrah (Eucalyptus marginata) seedlings
Publisher: Springer Science and Business Media LLC
Date: 02-03-2014
Pangenomes as a Resource to Accelerate Breeding of Under-Utilised Crop Species
Publisher: MDPI AG
Date: 28-02-2022
DOI: 10.3390/IJMS23052671
Abstract: Pangenomes are a rich resource to examine the genomic variation observed within a species or genera, supporting population genetics studies, with applications for the improvement of crop traits. Major crop species such as maize (Zea mays), rice (Oryza sativa), Brassica (Brassica spp.), and soybean (Glycine max) have had pangenomes constructed and released, and this has led to the discovery of valuable genes associated with disease resistance and yield components. However, pangenome data are not available for many less prominent crop species that are currently under-utilised. Despite many under-utilised species being important food sources in regional populations, the scarcity of genomic data for these species hinders their improvement. Here, we assess several under-utilised crops and review the pangenome approaches that could be used to build resources for their improvement. Many of these under-utilised crops are cultivated in arid or semi-arid environments, suggesting that novel genes related to drought tolerance may be identified and used for introgression into related major crop species. In addition, we discuss how previously collected data could be used to enrich pangenome functional analysis in genome-wide association studies (GWAS) based on studies in major crops. Considering the technological advances in genome sequencing, pangenome references for under-utilised species are becoming more obtainable, offering the opportunity to identify novel genes related to agro-morphological traits in these species.
One thousand plant transcriptomes and the phylogenomics of green plants
Publisher: Springer Science and Business Media LLC
Date: 23-10-2019
DOI: 10.1038/S41586-019-1693-2
Abstract: Green plants (Viridiplantae) include around 450,000–500,000 species 1,2 of great ersity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the ersity of plants in a broad sense (Archaeplastida), including green plants (Viridiplantae), glaucophytes (Glaucophyta) and red algae (Rhodophyta). Our analysis provides a robust phylogenomic framework for examining the evolution of green plants. Most inferred species relationships are well supported across multiple species tree and supermatrix analyses, but discordance among plastid and nuclear gene trees at a few important nodes highlights the complexity of plant genome evolution, including polyploidy, periods of rapid speciation, and extinction. Incomplete sorting of ancestral variation, polyploidization and massive expansions of gene families punctuate the evolutionary history of green plants. Notably, we find that large expansions of gene families preceded the origins of green plants, land plants and vascular plants, whereas whole-genome duplications are inferred to have occurred repeatedly throughout the evolution of flowering plants and ferns. The increasing availability of high-quality plant genome sequences and advances in functional genomics are enabling research on genome evolution across the green tree of life.
Balancing growth amidst salinity stress – lifestyle perspectives from the extremophyte model Schrenkiella parvula
Publisher: Cold Spring Harbor Laboratory
Date: 28-08-2021
DOI: 10.1101/2021.08.27.457575
Abstract: Schrenkiella parvula , a leading extremophyte model in Brassicaceae, can grow and complete its life cycle under multiple environmental stresses, including high salinity. While foundational genomic resources have been created for S. parvula , a comprehensive physiological or structural characterization of its salt stress responses is absent. We aimed to identify the influential traits that lead to stress-resilient growth of this species. We examined salt-induced changes in the physiology and anatomy of S. parvula throughout its lifecycle across multiple tissues. We found that S. parvula maintains or even exhibits enhanced growth during various developmental stages at salt stress levels known to inhibit growth in Arabidopsis and most crops. The resilient growth of S. parvula was associated with key traits that synergistically allow continued primary root growth, expansion of xylem vessels across the root-shoot continuum, and a high capacity to maintain tissue water levels by developing larger and thicker leaves while facilitating continued photosynthesis during salt stress. These traits at the vegetative phase were followed by a successful transition to the reproductive phase via early flowering, development of larger siliques, and production of viable seeds during salt stress. Additionally, the success of self-fertilization during early flowering stages was dependent on salt-induced filament elongation in flowers that aborted in the absence of salt. Our results suggest that the maintenance of leaf water status and enhancement of selfing in early flowers to ensure reproductive success, are among the most influential traits that contribute to the extremophyte lifestyle of S. parvula in its natural habitat. Schrenkiella parvula salt-resilient growth is facilitated by uncompromised primary root growth, expansion of xylem vessels, maintenance of leaf water status and photosynthesis, and early flowering.
A single amino acid change in the plant alternative oxidase alters the specificity of organic acid activation
Publisher: Wiley
Date: 09-07-1999
DOI: 10.1016/S0014-5793(99)00808-X
Abstract: The alternative oxidase is a quinol oxidase of the respiratory chain of plants and some fungi and protists. Its activity is regulated by redox-sensitive disulphide bond formation between neighbouring subunits and direct interaction with certain alpha-ketoacids. To investigate these regulatory mechanisms, we undertook site-directed mutagenesis of soybean and Arabidopsis alternative oxidase cDNAs, and expressed them in tobacco plants and Escherichia coli, respectively. The homologous C99 and C127 residues of GmAOX3 and AtAOX1a, respectively, were changed to serine. In the plant system, this substitution prevented oxidative inactivation of alternative oxidase and rendered the protein insensitive to pyruvate activation, in agreement with the recent results from other laboratories [Rhoads et al. (1998) J. Biol. Chem. 273, 30750-30756 Vanlerberghe et al. (1998) Plant Cell 10, 1551-1560]. However, the mutated protein is instead activated specifically by succinate. Measurements of AtAOX1a activity in bacterial membranes lacking succinate dehydrogenase confirmed that the stimulation of the mutant protein's activity by succinate did not involve its metabolism. Ex les of alternative oxidase proteins with the C to S substitution occur in nature and these oxidases are expected to be activated under most conditions in vivo, with implications for the efficiency of respiration in the tissues which express them.
Traits related to efficient acquisition and use of phosphorus promote diversification in Proteaceae in phosphorus‐impoverished landscapes
Publisher: Springer Science and Business Media LLC
Date: 22-03-2021
First report of black spot caused by boeremia exigua var. exigua on field pea in australia
Publisher: Scientific Societies
Date: 2012
Abstract: Black spot is a major disease of field pea (Pisum sativum L.) production across southern Australia. Known causal agents in Australia include one or more of Mycosphaerella pinodes (Berk. & Bloxam) Vestergr., Phoma medicaginis var. pinodella (L.K. Jones), Ascochyta pisi Lib., or P. koolunga (Davidson, Hartley, Priest, Krysinska-Kaczmarek, Herdina, McKay & Scott) (2), but other pathogens may also be associated with black spot symptoms. Black spot generally occurs on most plants and in most pea fields in Western Australia (W.A.), and during earlier winter/spring surveys of blackspot pathogens, some isolates were tentatively allocated to P. medicaginis var. pinodella despite different cultural characteristics on potato dextrose agar (PDA). Recently, single-spore isolations of a single culture each from an infested pea crop at Medina, Moora, and Mt. Barker in W.A. were made onto PDA. A PCR-based assay with TW81 and AB28 primers was used to lify from the ITS-5.8S rDNA region. Purified DNA products were sequenced for the three isolates and then BLASTn was used to compare sequences with those in GenBank. Our sequences (GenBank Accession Nos. JN37743, JN377439, and JN377438) had 100% nucleotide identity with P. exigua Desm. var. exigua accessions (GI13385450, GI169894028, and GI189163921), an earlier synonym of what is now known as Boeremia exigua var. exigua ([Desm.] Avesk , Gruyter & Verkley) (1). Davidson et al. (2) used the same primers to identify P. koolunga, but none of our isolates were P. koolunga. A suspension of 10 7 conidia ml –1 of each representative isolate was inoculated onto foliage of 15-day-old field pea cv. Dundale plants and maintained at % relative humidity for 72 h postinoculation. Control plants inoculated with just water remained symptomless. Brown lesions were evident by 8 to 10 days postinoculation and mostly 1 to 3 mm in diameter. B. exigua var. exigua was readily reisolated from infected leaves. Isolates have been lodged in the W.A. Culture Collection Herbarium maintained at the Department of Agriculture and Food W.A. (Accession Nos. WAC13500, WAC13502, and WAC13501 from Medina, Moora, and Mt. Barker, respectively). Outside Australia, its synonym P. exigua var. exigua is a known pathogen of field pea (4), other legumes including common bean (Phaseolus vulgaris L.) (4) and soybean (Glycine max [L.] Merr.) (3), and is known to produce phytotoxic cytochalasins. In eastern Australia, P. exigua var. exigua has been reported on common bean (1930s and 1950s), phasey bean (Macroptilium lathyroides [L.] Urb.) and siratro (M. atropurpureum (DC.) Urb.) (1950s and 1960s), mung bean (Vigna radiata [L.] Wilczek.) (1960s), ramie (Boehmeria nivea [L.] Gaudich.) (1939), potato (Solanum tuberosum L.) (1980s), and pyrethrum (Tanacetum cinerariifolium [Trevir.] Schultz Bip.) (2004 and 2007) (Australian Plant Pest Database). To our knowledge, this the first report of B. exigua var. exigua on field pea in Australia, and because of its potential to be a significant pathogen on field pea, warrants further evaluation. References: (1) M. M. Avesk et al. Stud. Mycol. 65:1, 2010. (2) J. A. Davidson et al. Mycologia 101:120, 2009. (3) L. Irinyi et al. Mycol. Res. 113:249, 2009. (4) J. Marcinkowska. Biul. Inst. Hod. Aklim. Rosl. 190:169, 1994.
Metabolic acclimation supports higher aluminium-induced secretion of citrate and malate in an aluminium-tolerant hybrid clone of Eucalyptus
Publisher: Springer Science and Business Media LLC
Date: 06-01-2021
DOI: 10.1186/S12870-020-02788-4
Abstract: Eucalyptus is the main plantation wood species, mostly grown in aluminized acid soils. To understand the response of Eucalyptus clones to aluminum (Al) toxicity, the Al-tolerant Eucalyptus grandis × E. urophylla clone GL-9 (designated “G9”) and the Al-sensitive E. urophylla clone GL-4 (designated “W4”) were employed to investigate the production and secretion of citrate and malate by roots. Eucalyptus seedlings in hydroponics were exposed to the presence or absence of 4.4 mM Al at pH 4.0 for 24 h. The protein synthesis inhibitor cycloheximide (CHM) and anion channel blocker phenylglyoxal (PG) were applied to explore possible pathways involved in organic acid secretion. The secretion of malate and citrate was earlier and greater in G9 than in W4, corresponding to less Al accumulation in G9. The concentration of Al in G9 roots peaked after 1 h and decreased afterwards, corresponding with a rapid induction of malate secretion. A time-lag of about 6 h in citrate efflux in G9 was followed by robust secretion to support continuous Al-detoxification. Malate secretion alone may alleviate Al toxicity because the peaks of Al accumulation and malate secretion were simultaneous in W4, which did not secrete appreciable citrate. Enhanced activities of citrate synthase (CS) and phosphoenolpyruvate carboxylase (PEPC), and reduced activities of isocitrate dehydrogenase (IDH), aconitase (ACO) and malic enzyme (ME) were closely associated with the greater secretion of citrate in G9. PG effectively inhibited citrate and malate secretion in both Eucalyptus clones. CHM also inhibited malate and citrate secretion in G9, and citrate secretion in W4, but notably did not affect malate secretion in W4. G9 immediately secrete malate from roots, which had an initial effect on Al-detoxification, followed by time-delayed citrate secretion . Pre-existing anion channel protein first contributed to malate secretion, while synthesis of carrier protein appeared to be needed for citrate excretion. The changes of organic acid concentrations in response to Al can be achieved by enhanced CS and PEPC activities, but was supported by changes in the activities of other enzymes involved in organic acid metabolism. The above information may help to further explore genes related to Al-tolerance in Eucalyptus .
Delayed greening in phosphorus-efficient Hakea prostrata (Proteaceae) is a photoprotective and nutrient-saving strategy
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/FP19285
Abstract: Hakea prostrata R.Br. (Proteaceae) shows a ‘delayed greening’ strategy of leaf development characterised by reddish young leaves that become green as they mature. This trait may contribute to efficient use of phosphorus (P) during leaf development by first investing P in the development of leaf structure followed by maturation of the photosynthetic machinery. In this study, we investigated the properties of delayed greening in a highly P-efficient species to enhance our understanding of the ecological significance of this trait as a nutrient-saving and photoprotective strategy. In glasshouse-grown plants, we assessed foliar pigments, fatty acids and nutrient composition across five leaf developmental stages. Young leaves had higher concentrations of anthocyanin, P, nitrogen (N), copper (Cu), xanthophyll-cycle pigments and saturated fatty acids than mature leaves. As leaves developed, the concentration of anthocyanins decreased, whereas that of chlorophyll and the double bond index of fatty acids increased. In mature leaves, ~60% of the fatty acids was α-linolenic acid (C18:3 n-3). Mature leaves also had higher concentrations of aluminium (Al), calcium (Ca) and manganese (Mn) than young leaves. We conclude that delayed greening in H. prostrata is a strategy that saves P as well as N and Cu through sequential allocation of these resources, first to cell production and structural development, and then to supplement chloroplast development. This strategy also protects young leaves against photodamage and oxidative stress during leaf expansion under high-light conditions.
Nitrogen addition in a freshwater marsh alters the quality of senesced leaves, promoting decay rates and changing nutrient dynamics during the standing-dead phase
Publisher: Springer Science and Business Media LLC
Date: 27-05-2017
Photosynthetic Performance and Fertility Are Repressed in GmAOX2b Antisense Soybean
Publisher: Oxford University Press (OUP)
Date: 22-01-2010
Abstract: The alternative oxidase (AOX) is a cyanide-resistant oxidase that provides an alternative outlet for electrons from the respiratory electron transport chain embedded in the inner membrane of plant mitochondria. Examination of soybean (Glycine max) plants carrying a GmAOX2b antisense gene showed AOX to have a central role in reproductive development and fecundity. In three independently transformed antisense lines, seed set was reduced by 16% to 43%, whereas ovule abortion increased by 1.2- to 1.7-fold when compared with nontransgenic transformation control plants. Reduced fecundity was associated with reductions in whole leaf cyanide-resistant, salicylhydroxamic acid-sensitive respiration and net photosynthesis, but there was no change in total respiration in the dark. The frequency of potential fertilization events was reduced by at least one-third in the antisense plants as a likely consequence of prefertilization defects. Pistils of the antisense plants contained a higher proportion of immature-sized, nonfertile embryo sacs compared with nontransgenic control plants. Increased rates of pollen abortion in vivo and reduced rates of pollen germination in vitro suggested that the antisense gene compromised pollen development and function. Reciprocal crosses between antisense and nontransgenic plants revealed that pollen produced by antisense plants was less active in fertilization. Taken together, the results presented here indicate that AOX expression has an important role in determining normal gametophyte development and function.
Comparative proteome analysis of the strawberry-Fusarium oxysporum f. sp. fragariae pathosystem reveals early activation of defense responses as a crucial determinant of host resistance
Publisher: American Chemical Society (ACS)
Date: 28-03-2013
DOI: 10.1021/PR301117A
Abstract: Fusarium wilt on strawberry caused by Fusarium oxysporum f. sp. fragariae (Fof) is a serious threat to commercial strawberry production worldwide. However, resistance mechanisms of strawberry against Fof remain unknown. To reveal the defense responses of strawberry against Fof, comparative proteome analyses were conducted to determine temporal changes in root proteomes of the resistant cv. Festival and susceptible cv. Camarosa from 4 to 72 h post inoculation with Fof. Analysis of proteins separated by two-dimensional gel electrophoresis revealed 79 Fof-responsive proteins with significant differences in abundance (P < 0.05 and greater than 2-fold) in the resistant and/or susceptible cultivar. The 79 proteins were identified through MALDI-TOF/TOF MS/MS analysis, and were mainly involved in primary, secondary and protein metabolism, stress and defense responses, antioxidant and detoxification mechanisms, and hormone biosynthesis. Among these, pathogenesis-related proteins and proteins involved in reactive oxygen species detoxification, ethylene/jasmonic acid signaling pathways, secondary metabolite biosynthesis, glycolysis and/or ubiquitin/26S proteasome-mediated protein degradation have great potential in mediating strawberry resistance against Fof. Protein modification may also have an important contribution. This study provides the first insights into strawberry resistance mechanisms against Fof, opening novel avenues to engineer new strawberry cultivars with improved disease resistance and to develop more effective and sustainable disease management strategies.
Chloroplast DNA inheritance and variation in Leucadendron species (Proteaceae) as revealed by PCR-RFLP
Publisher: Springer Science and Business Media LLC
Date: 10-09-2004
DOI: 10.1007/S00122-004-1800-Z
Abstract: The inheritance of chloroplast DNA (cpDNA) in Leucadendron species was studied by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. A total of 100 progeny from five interspecific crosses involving seven parental species were tested, and all progeny exhibited the cpDNA restriction fragment pattern of the female parent, indicating that cpDNA in Leucadendron is maternally inherited. PCR-RFLP was also employed to study cpDNA variation among 21 Leucadendron species. Parsimony analysis using a heuristic search resulted in a phylogenetic tree that showed limited agreement to the taxonomic classification of Leucadendron species, based on morphological characteristics. The incongruence between cpDNA phylogenetic and taxonomic groupings in Leucadendron may be due to reticulate evolution involving a combination of hybridization and introgression, convergent evolution and/or lineage sorting at the interspecific, intersubsectional and intersectional levels.
Molecular variation and fingerprinting of Leucadendron cultivars (Proteaceae) by ISSR markers
Publisher: Oxford University Press (OUP)
Date: 24-03-2005
DOI: 10.1093/AOB/MCI127
Tight control of sulfur assimilation
Publisher: Wiley
Date: 28-06-2017
DOI: 10.1111/NPH.14640
Abstract: Hakea prostrata (Proteaceae) has evolved in extremely phosphorus (P)‐impoverished habitats. Unlike species that evolved in P‐richer environments, it tightly controls its nitrogen (N) acquisition, matching its low protein concentration, and thus limiting its P requirement for ribosomal RNA (rRNA). Protein is a major sink for sulfur (S), but the link between low protein concentrations and S metabolism in H. prostrata is unknown, although this is pivotal for understanding this species’ supreme adaptation to P‐impoverished soils. Plants were grown at different sulfate supplies for 5 wk and used for nutrient and metabolite analyses. Total S content in H. prostrata was unchanged with increasing S supply, in sharp contrast with species that typically evolved in environments where P is not a major limiting nutrient. Unlike H. prostrata , other plants typically store excess available sulfate in vacuoles. Like other species, S‐starved H. prostrata accumulated arginine, lysine and O‐acetylserine, indicating S deficiency. Hakea prostrata tightly controls its S acquisition to match its low protein concentration and low demand for rRNA , and thus P, the largest organic P pool in leaves. We conclude that the tight control of S acquisition, like that of N, helps H. prostrata to survive in P‐impoverished environments.
A tomato alternative oxidase protein with altered regulatory properties
Publisher: Elsevier BV
Date: 09-4220
DOI: 10.1016/S0005-2728(03)00112-9
Abstract: We have investigated the expression and regulatory properties of the two alternative oxidase (Aox) proteins that are expressed in tomato (Lycopersicon esculentum L. Mill cv. Sweetie) after storage of green fruit at 4 degrees C. Four Aox genes were identified in the tomato genome, of which two (LeAox1a and LeAox1b) were demonstrated to be expressed in cold-treated fruit. The activity and regulatory properties of LeAox1a and LeAox1b were assayed after expression of each protein in yeast cells (Saccharomyces cerevisiae), proving that each is an active Aox protein. The LeAox1b protein was shown to have altered regulatory properties due to the substitution of a Ser for the highly conserved Cys(I) residue. LeAox1b could not form inactive disulfide-linked dimers and was activated by succinate instead of pyruvate. This is the first ex le of a dicot species expressing a natural Cys(I)/Ser isoform. The implications of the existence and expression of such Aox isoforms is discussed in the light of the hypothesised role for Aox in plant metabolism.
Draft genome sequence of the plant growth-promoting bacterium pseudomonas pseudoalcaligenes KB-10
Publisher: American Society for Microbiology
Date: 20-05-2021
DOI: 10.1128/MRA.00311-21
Abstract: Pseudomonas pseudoalcaligenes KB-10 can enhance salinity tolerance in coriander plants. We report a draft genome sequence of P. pseudoalcaligenes KB-10, comprising a 5,241,174-bp circular chromosome containing 4,921 genes, with a GC content of 62.97%.
Leaf phosphorus allocation to chemical fractions and its seasonal variation in south-western Australia is a species-dependent trait
Publisher: Elsevier BV
Date: 11-2023
Phosphorus nutrition of phosphorus-sensitive Australian native plants: Threats to plant communities in a global biodiversity hotspot
Publisher: Oxford University Press (OUP)
Date: 17-05-2013
Regulation of phosphate starvation responses in higher plants
Publisher: Oxford University Press (OUP)
Date: 24-02-2010
DOI: 10.1093/AOB/MCQ015
Balancing growth amidst salt stress - lifestyle perspectives from the extremophyte model Schrenkiella parvula
Publisher: Wiley
Date: 23-08-2023
DOI: 10.1111/TPJ.16396
Abstract: Schrenkiella parvula , a leading extremophyte model in Brassicaceae, can grow and complete its lifecycle under multiple environmental stresses, including high salinity. Yet, the key physiological and structural traits underlying its stress‐adapted lifestyle are unknown along with trade‐offs when surviving salt stress at the expense of growth and reproduction. We aimed to identify the influential adaptive trait responses that lead to stress‐resilient and uncompromised growth across developmental stages when treated with salt at levels known to inhibit growth in Arabidopsis and most crops. Its resilient growth was promoted by traits that synergistically allowed primary root growth in seedlings, the expansion of xylem vessels across the root‐shoot continuum, and a high capacity to maintain tissue water levels by developing thicker succulent leaves while enabling photosynthesis during salt stress. A successful transition from vegetative to reproductive phase was initiated by salt‐induced early flowering, resulting in viable seeds. Self‐fertilization in salt‐induced early flowering was dependent upon filament elongation in flowers otherwise aborted in the absence of salt during comparable plant ages. The maintenance of leaf water status promoting growth, and early flowering to ensure reproductive success in a changing environment, were among the most influential traits that contributed to the extremophytic lifestyle of S. parvula .
Phosphorus nutrition in Proteaceae and beyond
Publisher: Springer Science and Business Media LLC
Date: 04-08-2015
Abstract: Proteaceae in southwestern Australia have evolved on some of the most phosphorus-impoverished soils in the world. They exhibit a range of traits that allow them to both acquire and utilize phosphorus highly efficiently. This is in stark contrast with many model plants such as Arabidopsis thaliana and crop species, which evolved on soils where nitrogen is the major limiting nutrient. When exposed to low phosphorus availability, these plants typically exhibit phosphorus-starvation responses, whereas Proteaceae do not. This Review explores the traits that account for the very high efficiency of acquisition and use of phosphorus in Proteaceae, and explores which of these traits are promising for improving the phosphorus efficiency of crop plants.
Heartwood-specific transcriptome and metabolite signatures of tropical sandalwood (Santalum album) reveal the final step of (Z)-santalol fragrance biosynthesis
Publisher: Wiley
Date: 15-04-2016
DOI: 10.1111/TPJ.13162
Abstract: Tropical sandalwood (Santalum album) produces one of the world's most highly prized fragrances, which is extracted from mature heartwood. However, in some places such as southern India, natural populations of this slow-growing tree are threatened by over-exploitation. Sandalwood oil contains four major and fragrance-defining sesquiterpenols: (Z)-α-santalol, (Z)-β-santalol, (Z)-epi-β-santalol and (Z)-α-exo-bergamotol. The first committed step in their biosynthesis is catalyzed by a multi-product santalene/bergamotene synthase. Sandalwood cytochromes P450 of the CYP76F sub-family were recently shown to hydroxylate santalenes and bergamotene however, these enzymes produced mostly (E)-santalols and (E)-α-exo-bergamotol. We hypothesized that different santalene/bergamotene hydroxylases evolved in S. album to stereo-selectively produce (E)- or (Z)-sesquiterpenols, and that genes encoding (Z)-specific P450s contribute to sandalwood oil formation if co-expressed in the heartwood with upstream genes of sesquiterpene biosynthesis. This hypothesis was validated by the discovery of a heartwood-specific transcriptome signature for sesquiterpenoid biosynthesis, including highly expressed SaCYP736A167 transcripts. We characterized SaCYP736A167 as a multi-substrate P450, which stereo-selectively produces (Z)-α-santalol, (Z)-β-santalol, (Z)-epi-β-santalol and (Z)-α-exo-bergamotol, matching authentic sandalwood oil. This work completes the discovery of the biosynthetic enzymes of key components of sandalwood fragrance, and highlights the evolutionary ersification of stereo-selective P450s in sesquiterpenoid biosynthesis. Bioengineering of microbial systems using SaCYP736A167, combined with santalene/bergamotene synthase, has potential for development of alternative industrial production systems for sandalwood oil fragrances.
Plant functional group controls litter decomposition rate and its temperature sensitivity
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.SCITOTENV.2018.01.162
Abstract: In boreal peatlands, litter decomposition plays an important role in modulating ecosystem carbon (C) cycling and nutrient turnover. However, how climate warming and plant functional group interact to affect litter decomposition is still unclear in these ecosystems. Here, we collected fresh litters of six plant functional groups (nitrogen (N)-fixing species, deciduous tree, deciduous shrub, evergreen shrub, graminoid, and Sphagnum moss) from a boreal peatland located in northeast China. A laboratory incubation experiment was used to determine the effect of temperature (10 °C vs. 20 °C) on microbial respiration and mass loss during decomposition. Among the six functional groups, the litters of N-fixing species and deciduous shrub, followed by deciduous tree, generally had the greatest mass losses and microbial respiration rates, whereas the Sphagnum moss decomposed with the slowest rate at both incubation temperatures. Increasing incubation temperature from 10 °C to 20 °C, microbial respiration rate and mass loss increased slightly for Sphagnum moss litters (25% and 19%, respectively), but increased dramatically for vascular plant litters (84-135% and 49-85%, respectively). For litters from vascular plants, both decomposition rate and temperature sensitivity showed a tight linear correlation with the initial C:N and C:phosphorus ratios. Considering that climate warming will cause increased dominance of woody plant species coupled with decreased cover by Sphagnum mosses, this study provides clear evidence that climate warming and the associated changes to vegetation community composition can synergistically accelerate plant litter decomposition in boreal peatlands.
Effects of litter mixtures on aerobic decomposition rate and its temperature sensitivity in a boreal peatland
Publisher: Elsevier BV
Date: 11-2019
Foliar nutrient allocation patterns in Banksia attenuata and Banksia sessilis differing in growth rate and adaptation to low-phosphorus habitats
Publisher: Oxford University Press (OUP)
Date: 03-02-2021
DOI: 10.1093/AOB/MCAB013
Abstract: Phosphorus (P) and nitrogen (N) are essential nutrients that frequently limit primary productivity in terrestrial ecosystems. Efficient use of these nutrients is important for plants growing in nutrient-poor environments. Plants generally reduce foliar P concentration in response to low soil P availability. We aimed to assess ecophysiological mechanisms and adaptive strategies for efficient use of P in Banksia attenuata (Proteaceae), naturally occurring on deep sand, and B. sessilis, occurring on shallow sand over laterite or limestone, by comparing the allocation of P among foliar P fractions. We carried out pot experiments with slow-growing B. attenuata, which resprouts after fire, and faster growing opportunistic B. sessilis, which is killed by fire, on substrates with different P availability using a randomized complete block design. We measured leaf P and N concentrations, photosynthesis, leaf mass per area, relative growth rate and P allocated to major biochemical fractions in B. attenuata and B. sessilis. The two species had similarly low foliar total P concentrations, but distinct patterns of P allocation to P-containing fractions. The foliar total N concentration of B. sessilis was greater than that of B. attenuata on all substrates. The foliar total P and N concentrations in both species decreased with decreasing P availability. The relative growth rate of both species was positively correlated with concentrations of both foliar nucleic acid P and total N, but there was no correlation with other P fractions. Faster growing B. sessilis allocated more P to nucleic acids than B. attenuata did, but other fractions were similar. The nutrient allocation patterns in faster growing opportunistic B. sessilis and slower growing B. attenuata revealed different strategies in response to soil P availability which matched their contrasting growth strategy.
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