ORCID Profile
0000-0002-9637-2073
Current Organisation
University of Adelaide
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Publisher: Wiley
Date: 07-2021
DOI: 10.1002/PS.6518
Abstract: Hordeum glaucum Steud. is an important grass weed species in South Australia that has evolved resistance to glyphosate. This study investigated the mode of inheritance of glyphosate resistance in this species. Hand‐pollination of glyphosate susceptible and resistant populations generated two F 1 in iduals, selfed to yield F 2 progenies. In dose–response experiments, the F 2 progenies showed intermediate response between the two parent populations. High variation in EPSPS gene copies was observed among F 2 in iduals, with some in iduals possessing more gene copies than the resistant parent population. No evidence of a Mendelian single‐gene pattern of inheritance was observed. Inheritance of gene lification in H. glaucum is non‐Mendelian. © 2021 Society of Chemical Industry.
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.PESTBP.2019.03.004
Abstract: Indian hedge mustard (Sisymbrium orientale) (IHM) is an important broadleaf weed across southern Australia. Resistance to sulfonylurea (SU) herbicides that inhibit acetohydroxyacid synthase (AHAS) is extensive in Australia, but resistance to imidazolinone (IMI) herbicides has only been reported recently. The AHAS-mutation profile of 65 IHM populations collected randomly from cropped fields was investigated to better understand the extent and types of resistance present. Resistance to SU herbicides was present in 40% of the populations and resistance to IMI herbicides in 11%. Mutations were identified in SoAHAS by sequence analysis, and included previously reported amino-acid substitutions at Pro197 and Trp574, but also new substitutions at Pro197 and Asp376 for this species. One population with possible non-target-site resistance was identified. Germination studies with fresh seed found no significant effect by mutations in SoAHAS on germination however, population factors had a large effect on germination in S. orientale. Resistance to AHAS-inhibiting herbicides in populations of S. orientale is endowed by mutations in SoAHAS in all but one population examined. Mutations at Pro197 conferring resistance to SU herbicides were most common, while mutations at Trp574 that provide resistance to IMI herbicides are also present.
Publisher: Wiley
Date: 26-02-2018
DOI: 10.1002/PS.4858
Abstract: An oriental mustard population (P3) collected near Quambatook, Victoria was identified as being resistant to diflufenican by screening with the field rate (200 g a.i. ha Dose-response experiments confirmed that population P3 was 140-fold more resistant to diflufenican than susceptible populations, as determined by the comparison of 50% lethal (LD Resistance to diflufenican in oriental mustard is conferred by the Leu-526-Val mutation in the PDS gene. Inheritance of resistance is managed by a single gene with high levels of dominance. © 2018 Society of Chemical Industry.
Publisher: Wiley
Date: 03-2017
DOI: 10.1111/WBM.12111
Publisher: Wiley
Date: 17-10-2017
DOI: 10.1111/WBM.12133
Publisher: MDPI AG
Date: 26-10-2021
Abstract: Poa annua is a cosmopolitan, cool-season grass species regarded as one of the most significant weeds of turfgrass. It is mainly controlled by herbicides however, repeated use of herbicides in golf turf has resulted in the evolution of multiple-herbicide resistant P. annua. Four field experiments were performed in autumn and spring in golf turf to identify effective herbicide options to control multiple herbicide-resistant P. annua. In herbicide resistance screening, the trial site population (SA1) was found to be susceptible to amicarbazone and terbuthylazine, but resistant to simazine and metribuzin at the field rate of each herbicide. Consistent with the results of the pot study, the PSII-inhibiting herbicides amicarbazone and terbuthylazine provided the best control (80–100%) of P. annua in both autumn and spring trials with minimal damage to the turf. In contrast, the other two PSII-inhibiting herbicides, metribuzin and simazine, were relatively ineffective in controlling P. annua in the field. Indaziflam also performed well in both autumn trials and reduced P. annua occurrence by %. Pyroxasulfone and s-metolachlor only provided moderate weed control in both the autumn and spring trials, reducing P. annua occurrence by 50%. Among the nine different herbicides, amicarbazone and terbuthylazine were found to be most effective for spring and autumn application in turf. As resistance to some PSII-inhibiting herbicides has already evolved in this field population, the use of amicarbazone and terbuthylazine needs to be integrated with other herbicide modes of action and non-chemical tactics to delay the onset of resistance to them.
Publisher: Wiley
Date: 30-09-2014
DOI: 10.1111/WRE.12050
Publisher: Cambridge University Press (CUP)
Date: 09-12-2020
DOI: 10.1017/WET.2020.134
Abstract: In southern Australia, annual sowthistle and prickly lettuce have become more prevalent following the adoption of reduced tillage cropping systems. They are especially problematic in lentil and other pulse crops, which are weakly competitive and have few herbicide options available for POST control of broadleaf weeds. This study aimed to evaluate the influence of management in a previous cereal crop on weed densities in a subsequent crop. At two field sites, crop seeding density and POST herbicide treatments (a conventional choice that included metsulfuron-methyl and MCPA and a proactive choice that included bromoxynil, picolinafen, and MCPA) were applied to a wheat crop, and weed density was assessed at the beginning of the following season to measure for a legacy effect of the treatments. Study site populations were also screened for herbicide resistance and were found to have high (≥90% survival) ALS inhibitor resistance. Crop competition treatments had no effect on weed populations, and effects of herbicide treatment were significant at only one of the sites. At this site, both herbicide treatments had lower weed densities than the nontreated in the first year, but the legacy effect was only significant for annual sowthistle density in the proactive treatment. At both sites, even where weeds were extremely sparse or completely controlled following herbicide treatment in the first year, moderate densities were observed the following year, indicating that colonization from the seedbank or adjacent areas could be contributing to weed numbers. Weed density assessments and accurate knowledge of the herbicide resistance status of target weeds should guide herbicide selection to maximize control.
Publisher: Cambridge University Press (CUP)
Date: 04-05-2020
DOI: 10.1017/WSC.2020.35
Abstract: Annual bluegrass ( Poa annua L.) is a problematic annual weed in established turf where the intensive use of herbicides has resulted in the evolution of herbicide resistance. In 2017, 31 populations of P. annua suspected to be resistant to herbicides commonly used to control this weed in turf were collected from golf courses across southeastern Australia to check the resistance status to different herbicide groups. All populations were found to be resistant to multiple turf herbicides. Dose–response experiments confirmed resistance to propyzamide, simazine, rimsulfuron, foramsulfuron, endothall, and pinoxaden. Levels of resistance to rimsulfuron ( -fold), foramsulfuron ( -fold), endothall ( -fold), and pinoxaden ( .3-fold) compared with the susceptible population were high, but levels of resistance to propyzamide ( -fold) and simazine ( -fold) were lower. Considerable variation in resistance to endothall and pinoxaden was observed among the populations of P. annua . Target-site resistance was confirmed for acetolactate synthase and acetyl-CoA carboxylase inhibitors, but not for photosystem II and microtubule assembly inhibitors. This study documented the extensive resistance to herbicides in P. annua from turf in Australia. Three of the populations investigated exhibited multiple resistance to herbicides from five mechanisms of action. The identification of multiple-resistant P. annua on several golf courses is a serious concern for turf managers.
Publisher: Wiley
Date: 04-01-2017
DOI: 10.1002/PS.4493
Abstract: In Australia, the extensive use of clethodim for the control of Lolium rigidum has resulted in the evolution of many clethodim-resistant L. rigidum populations. Five clethodim-resistant populations of L. rigidum were analysed for the inheritance of clethodim resistance. Reciprocal crosses were made between resistant (R) and susceptible (S) populations. Within crosses, dose-responses of reciprocal F The results of this study indicate that different patterns of clethodim resistance in L. rigidum exist. © 2016 Society of Chemical Industry.
Publisher: Wiley
Date: 30-07-2019
DOI: 10.1002/PS.5087
Abstract: An oriental mustard population (P40) was identified as resistant to diflufenican by screening at the field rate. As diflufenican and picolinafen both target phytoene desaturase (PDS), cross-resistance to picolinafen was suspected. The mechanism of resistance and its inheritance to diflufenican and picolinafen were investigated. At the lethal dose (LD Resistance to diflufenican and picolinafen in the P40 population is likely conferred by Leu-498-Val and Glu-425-Asp mutations in the PDS gene. Inheritance of resistance to these herbicides is managed by a single dominant gene. © 2018 Society of Chemical Industry.
Publisher: Cambridge University Press (CUP)
Date: 06-2016
Abstract: Rigid ryegrass, an important annual weed species in cropping regions of southern Australia, has evolved resistance to 11 major groups of herbicides. Dose–response studies were conducted to determine response of three clethodim-resistant populations and one clethodim-susceptible population of rigid ryegrass to three different frost treatments (−2 C). Clethodim-resistant and -susceptible plants were exposed to frost in a frost chamber from 4:00 P.M. to 8:00 A.M. for three nights before or after clethodim application and were compared with plants not exposed to frost. A reduction in the level of clethodim efficacy was observed in resistant populations when plants were exposed to frost for three nights before or after clethodim application. In the highly resistant populations, the survival percentage and LD 50 were higher when plants were exposed to frost before clethodim application compared with frost after clethodim application. However, frost treatment did not influence clethodim efficacy of the susceptible population. Sequencing of the acetyl coenzyme A carboxylase (ACCase) gene of the three resistant populations identified three known mutations at positions 1781, 2041, and 2078. However, most in iduals in the highly resistant populations did not contain any known mutation in ACCase, suggesting the resistance mechanism was a nontarget site. The effect of frost on clethodim efficacy in resistant plants may be an outcome of the interaction between frost and the clethodim resistance mechanism(s) present.
Publisher: Wiley
Date: 08-09-2023
DOI: 10.1002/PS.7743
Abstract: Control of prickly lettuce has become increasingly difficult for lentil growers in southern Australia due to widespread resistance to common herbicides, a lack of alternative herbicide options, and prolific production of highly mobile seed. This study aimed to quantify ALS‐inhibiting herbicide resistance in the Mid North (MN) and Yorke Peninsula (YP) of South Australia, characterise the resistance mutations present, and investigate population structure and gene flow in this species. Resistance was identified in all populations tested, with average survival of 92% to chlorsulfuron and 95% to imazamox + imazapyr. Five different amino acid substitutions were identified at Proline‐197 of the ALS gene. There was no significant difference in the LD 50 between plants with these five different substitutions when treated with metsulfuron‐methyl, however, imidazolinone resistance level was higher in plants with a phenylalanine substitution and lower in plants with a serine. Population structure based on 701 SNPs and 271 in iduals provided evidence for both the independent evolution of the same mutation in different populations, as well as frequent short to medium distance dispersal accompanied by occasional long‐distance dispersal events. The overall inbreeding coefficient ( F IS ) was calculated at 0.5174, indicating an intermediate level of outcrossing despite the cross‐pollination experiment showing only low outcrossing. In the structure analyses, most in iduals from YP were assigned to a single cluster, whereas most in iduals from MN were assigned 50% to each of two clusters, indicating some genetic differences between these two regions, but also evidence for dispersal between them. Use of imidazolinone herbicides has selected for mutations conferring higher levels of resistance, such as the Pro‐197‐Phe mutation, and resulted in further spread of resistance in this species. This article is protected by copyright. All rights reserved.
Publisher: Wiley
Date: 12-06-2018
DOI: 10.1002/PS.5048
Abstract: There have been previous calls for, and efforts focused on, realizing the power and potential of weed genomics for better understanding of weeds. Sustained advances in genome sequencing and assembly technologies now make it possible for in idual research groups to generate reference genomes for multiple weed species at reasonable costs. Here, we present the outcomes from several meetings, discussions, and workshops focused on establishing an International Weed Genomics Consortium (IWGC) for a coordinated international effort in weed genomics. We review the 'state of the art' in genomics and weed genomics, including technologies, applications, and on-going weed genome projects. We also report the outcomes from a workshop and a global survey of the weed science community to identify priority species, key biological questions, and weed management applications that can be addressed through greater availability of, and access to, genomic resources. Major focus areas include the evolution of herbicide resistance and weedy traits, the development of molecular diagnostics, and the identification of novel targets and approaches for weed management. There is increasing interest in, and need for, weed genomics, and the establishment of the IWGC will provide the necessary global platform for communication and coordination of weed genomics research. © 2018 Society of Chemical Industry.
Publisher: Wiley
Date: 02-05-2017
DOI: 10.1002/PS.4573
Abstract: Five glyphosate-resistant populations of Chloris truncata originally collected from New South Wales were compared with one susceptible (S) population from South Australia to confirm glyphosate resistance and elucidate possible mechanisms of resistance. Based on the amounts of glyphosate required to kill 50% of treated plants (LD This study has identified EPSPS gene lification contributing to glyphosate resistance in C. truncata. In addition, a Glu-91-Ala mutation within EPSPS was identified that may contribute to glyphosate resistance in this species. © 2017 Society of Chemical Industry.
Publisher: Wiley
Date: 27-12-2021
DOI: 10.1002/PS.6754
Abstract: In initial screening, glyphosate was ineffective in controlling five Poa annua populations. These populations were tested for resistance, and studies undertaken to determine resistance mechanisms and inheritance pattern. Dose–response studies conducted at 16/12°C and 27/20°C on the five putative resistant populations showed low‐level resistance (1.4‐ to 2.5‐fold) to glyphosate. Shikimic acid accumulation in response to glyphosate confirmed differences among the populations, with greater shikimic acid accumulation in the susceptible population. The EPSPS gene copy number was 0.5‐ to 5.2‐fold greater in one resistant population (HT) than in the susceptible (S) population, but not in the others. EPSPS gene expression was five‐ to tenfold higher in HT compared with the susceptible population. Target site mutations, differences in glyphosate absorption or translocation or altered expression of aldo‐keto reductase ( AKR ) were not identified in any of the resistant populations. Crosses were successful between one resistant population and the susceptible population (P262‐16♂ ✕ S♀) and inheritance of glyphosate resistance appears to be controlled by a single, nuclear dominant gene in this population. Our study identified EPSPS gene lification in a South Australian glyphosate‐resistant P. annua population (HT). This mechanism of resistance was not identified in the other four glyphosate‐resistant populations, and other common mechanisms were excluded. Although the resistance mechanism in some P. annua populations remains unknown, inheritance studies with one population suggest the involvement of a single dominant gene. © 2021 Society of Chemical Industry.
Publisher: Cold Spring Harbor Laboratory
Date: 20-07-2023
DOI: 10.1101/2023.07.19.549613
Abstract: The International Weed Genomics Consortium is a collaborative group of researchers focused on developing genomic resources for the study of weedy plants. Weeds are attractive systems for basic and applied research due to their impacts on agricultural systems and capacity to swiftly adapt in response to anthropogenic selection pressures. Our goal is to use genomic information to develop sustainable and effective weed control methods and to provide insights about biotic and abiotic stress tolerance to assist crop breeding. Here, we outline resources under development by the consortium and highlight areas of research that will be impacted by these enabling resources.
Publisher: Wiley
Date: 30-12-2015
DOI: 10.1002/PS.3956
Abstract: A population of Sisymbrium orientale from South Australia has multiple resistance to auxinic herbicides and inhibitors of acetohydroxyacid synthase (AHAS). Inheritance of resistance to 2,4-D and chlorsulfuron was studied in this population. Crosses were made between seven resistant in iduals as pollen donors to seven susceptible in iduals. Sixteen F1 in iduals from three crosses were identified by their lack of strong epinasty when treated with 200 g 2,4-D ha(-1). These in iduals were selfed, and segregation analysis of strong epinasty in the resulting progeny fitted a 3:1 ratio for resistant:susceptible in iduals when treated with 200 g 2,4-D ha(-1), as predicted by a single major gene. A detailed dose-response analysis of the F2 populations to 2,4-D confirmed single-gene inheritance. Analysis of segregation to 1 g chlorsulfuron ha(-1), a concentration that kills all susceptible in iduals, was unable to determine the mode of inheritance. A detailed dose-response analysis indicated that two genes contributed to chlorsulfuron resistance: a dominant target-site mutation of Pro 197 to Ser and a second gene with dose-dependent dominance. This population has a single dominant allele conferring 2,4-D resistance, whereas two genes contribute to chlorsulfuron resistance. Single dominant gene inheritance demonstrates that 2,4-D resistance can be readily selected.
Publisher: Wiley
Date: 14-02-2018
DOI: 10.1002/PS.4845
Abstract: Two oriental mustard populations (P2 and P13) collected from Port Broughton, South Australia were identified as resistant to 2,4-D. The level of resistance, mechanism and the mode of inheritance for 2,4-D resistance in these populations were investigated. Populations P2 and P13 were confirmed to be resistant to 2,4-D at the field rate (600 g a.e. ha Resistance to 2,4-D in oriental mustard is likely due to reduced translocation of 2,4-D out of the treated leaf. Inheritance of 2,4-D resistance is conferred by a single gene with a high level of dominance. © 2017 Society of Chemical Industry.
Publisher: Springer Science and Business Media LLC
Date: 04-05-2020
DOI: 10.1186/S42269-020-00316-W
Abstract: Resistance to glyphosate has been reported in flaxleaf fleabane populations within a number of grain growing areas in southern Queensland and northern New South Wales and other cropping regions across Australia. To investigate the processes contributing to the evolution and spread of glyphosate-resistant flaxleaf fleabane, the resistant populations tested in dose-response experiments varied in their responses to glyphosate from two to eight times the recommended rate. The different dose responses obtained may indicate different mechanisms of resistance. This can possibly be attributed to an independent evolution of resistance. The results demonstrate that glyphosate resistance is widespread across Australia and has likely evolved multiple times as well as dispersing by seeds.
Publisher: Cambridge University Press (CUP)
Date: 09-2012
Abstract: Glyphosate is widely used for weed control in the grape growing industry in southern Australia. The intensive use of glyphosate in this industry has resulted in the evolution of glyphosate resistance in rigid ryegrass. Two populations of rigid ryegrass from vineyards, SLR80 and SLR88, had 6- to 11-fold resistance to glyphosate in dose-response studies. These resistance levels were higher than two previously well-characterized glyphosate-resistant populations of rigid ryegrass (SLR77 and NLR70), containing a modified target site or reduced translocation, respectively. Populations SLR80 and SLR88 accumulated less glyphosate, 12 and 17% of absorbed glyphosate, in the shoot in the resistant populations compared with 26% in the susceptible population. In addition, a mutation within the target enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) where Pro 106 had been substituted by either serine or threonine was identified. These two populations are more highly resistant to glyphosate as a consequence of expressing two different resistance mechanisms concurrently.
Publisher: CSIRO Publishing
Date: 07-2022
DOI: 10.1071/CP22088
Abstract: Context Lolium rigidum Gaudin (annual ryegrass) has remained the most problematic weed of crop production in Australia for more than 20 years. There is some evidence that this weed species can rapidly adapt to management practices including delayed crop sowing. Aims Studies were undertaken to determine genetic variation for seed dormancy within L. rigidum populations and its association with genes involved with gibberellic acid and abscisic acid synthesis. Methodology Populations of L. rigidum were grown in pots to select low and high dormancy cohorts. Seeds produced by these cohorts from each population were assessed for variation in seed dormancy. Seeds of high and low dormancy cohorts were concurrently assessed for seed dormancy and expression of LrABA1 and LrGA20ox genes, using quantitative real-time PCR. Results Presence of differences greater than two-fold in seed dormancy between populations from the same farm indicated in situ selection for seed dormancy, most likely in response to management. Low and high dormancy cohorts of all populations maintained clear differences in seed dormancy in both years of assessment. Differences in seed dormancy between low and high dormancy cohorts were significantly correlated with LrABA1 and LrGA20ox gene expression. Conclusions This investigation has provided clear evidence of the presence of genetic variation for seed dormancy within L. rigidum populations. Implications The presence of genetic variation for seed dormancy in L. rigidum populations will allow this weed to adapt rapidly to changes in weed management practices such as delayed sowing of crops.
Publisher: Cambridge University Press (CUP)
Date: 03-2014
Abstract: Populations of rigid ryegrass with resistance to glyphosate have started to become a problem on fence lines of cropping fields of southern Australian farms. Seed of rigid ryegrass plants that survived glyphosate application were collected from two fence line locations in Clare, South Australia. Dose–response experiments confirmed resistance of these fence line populations to glyphosate. Both populations required 9- to 15-fold higher glyphosate dose to achieve 50% mortality in comparison to a standard susceptible population. The mechanism of resistance in these populations was investigated. Sequencing a conserved region of the gene encoding 5-enolpyruvyl-shikimate-3-phosphate synthase identified no differences between the resistant and susceptible populations. Absorption of glyphosate into leaves of the resistant populations was not different from the susceptible population. However, the resistant plants retained significantly more herbicide in the treated leaf blades than did the susceptible plants. Conversely, susceptible plants translocated significantly more herbicide to the leaf sheaths and untreated leaves than the resistant plants. The differences in translocation pattern for glyphosate between the resistant and susceptible populations of rigid ryegrass suggest resistance is associated with altered translocation of glyphosate in the fence line populations.
Publisher: International Society of Communication and Development Between Universities (ISCDBU)
Date: 09-2019
Publisher: Proceedings of the National Academy of Sciences
Date: 25-02-2022
Abstract: Synthetic auxin herbicides intersect basic plant developmental biology and applied weed management. We investigated resistance to 2,4-D in the Australian weed Sisymbrium orientale (Indian hedge mustard). We identified a mechanism involving an in-frame 27-bp deletion in the degron tail of auxin coreceptor IAA2, one member of the gene family of Aux/IAA auxin co-receptors. We show that this deletion in IAA2 is a gain-of-function mutation that confers synthetic auxin resistance. This field-evolved mechanism of resistance to synthetic auxin herbicides confirms previous biochemical studies showing the role of the Aux/IAA degron tail in regulating Aux/IAA protein degradation upon auxin perception. The deletion mutation could be generated in crops using gene-editing approaches for cross-resistance to multiple synthetic auxin herbicides.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.PESTBP.2019.01.005
Abstract: Two mutations Leu498 and Glu425 in the PDS gene were identified as the main cause conferring resistance to diflufenican and picolinafen in two oriental mustard populations P3 and P40. As mutations are suspected to affect fitness, this study was designed to test this hypothesis using the F
Publisher: CSIRO Publishing
Date: 28-06-2022
DOI: 10.1071/CP22118
Abstract: Context Bromus diandrus Roth is a serious weed of cereal-based cropping systems in South Australia. Its adaptation to local climate and production systems, prolific seed production and evolution of herbicide resistance have made this weed difficult to manage. Aims Studies were undertaken to determine genetic variation in seed dormancy within B. diandrus populations and its association with genes involved with gibberellic acid and abscisic acid synthesis. Methodology Seeds from five B. diandrus populations were s led during 2017 from commercial fields and planted during 2018 in pots. Protracted seedling emergence in these populations allowed selection of low and high dormancy cohorts. Seeds produced by these cohorts from each population were evaluated for variation in seed dormancy in the following year. The process of cohort selection and seed dormancy evaluation was repeated. The mechanism regulating seed dormancy was investigated in 2020 by assessing seeds of low and high dormancy cohorts concurrently for dormancy and for expression of ABA1 and GA20ox genes, using quantitative real-time PCR. Results There was at least a two-fold difference in seed dormancy among populations collected from different farms. Low and high dormancy cohorts within each population maintained consistent differences in seed dormancy in both years of assessment, suggesting genetic control over this trait. Differences in seed dormancy between low and high dormancy cohorts were significantly correlated with ABA1 and GA20ox gene expression. Conclusions Large differences in seed dormancy exist between in iduals in B. diandrus populations. The study has provided evidence of genetic variation for seed dormancy within B. diandrus populations, which was associated with ABA1 and GA20ox gene expression. Implications Presence of genetic variation for seed dormancy could play an important role in adaptation to escape pre-sowing weed-control tactics, meaning that B. diandrus could become an even greater problem in field crops grown in this region.
Publisher: Wiley
Date: 02-12-2019
DOI: 10.1002/PS.5671
Abstract: Glyphosate failed to control two populations of Hordeum glaucum (northern barley grass) along a fence line and around stockyards near Arthurton on the Yorke Peninsula, South Australia after more than a decade of regular use of glyphosate. These were investigated to confirm resistance and to determine resistance mechanisms. Dose-response experiments confirmed resistance of these populations to glyphosate with resistance levels of 2.8-6.6-fold compared with two susceptible populations. Shikimate assays confirmed resistance to glyphosate with less shikimate accumulation in the resistant populations compared with the susceptible populations. Quantitative PCR of genomic DNA showed increased gene copy number in the resistant populations with 9-11-fold more copies of EPSPS compared with the susceptible populations, suggesting resistance is likely conferred by gene lification. This study identified the first ex les of glyphosate resistance in the grass species H. glaucum with resistance associated with EPSPS gene lification. © 2019 Society of Chemical Industry.
Publisher: Cambridge University Press (CUP)
Date: 12-2015
Abstract: Clethodim resistance was identified in 12 rigid ryegrass populations from winter cropping regions in four different states of Australia. Clethodim had failed to provide effective control of these populations in the field and resistance was suspected. Dose–response experiments confirmed resistance to clethodim and butroxydim in all populations. During 2012, the LD 50 of resistant populations ranged from 10.2 to 89.3 g ha −1 , making them 3 to 34–fold more resistant to clethodim than the susceptible population. Similarly, GR 50 of resistant population varied from 8 to 37.1 g ha −1 , which is 3 to 13.9–fold higher than the susceptible population. In 2013, clethodim-resistant populations were 7.8 to 35.3–fold more resistant to clethodim than the susceptible population. The higher resistance factor in 2013, especially in moderately resistant populations, could have been associated with lower ambient temperatures during the winter of 2013. These resistant populations had also evolved cross-resistance to butroxydim. The resistant populations required 1.3 to 6.6–fold higher butroxydim dose to achieve 50% mortality and 3 to 27–fold more butroxydim for 50% biomass reduction compared to the standard susceptible population. Sequencing of the target-site ACCase gene identified five known ACCase substitutions (isoleucine-1781-leucine, isoleucine-2041-asparagine, aspartate-2078-glycine, and cysteine-2088-arginine, and glycine-2096-alanine) in these populations. In nine populations, multiple ACCase mutations were present in different in iduals. Furthermore, two alleles with different mutations were present in a single plant of rigid ryegrass in two populations.
Publisher: Cambridge University Press (CUP)
Date: 06-2015
Abstract: Acetyl coenzyme A carboxylase (ACCase)-inhibiting herbicides affect fatty acid biosynthesis in plants and are widely used to control smooth and hare barley in dicot crops in Australia. Recently, growers have experienced difficulty in controlling smooth and hare barley with herbicides from this mode of action. Dose–response experiments conducted on five suspected resistant populations confirmed varying levels of resistance to quizalofop and haloxyfop. The level of resistance in these populations was greater than 27-fold to quizalofop and greater than 15-fold to haloxyfop. The quizalofop dose required to reduce shoot biomass by 50% (GR 50 ) for the resistant populations varied from 52.6 to 111.9 g ha −1 , and for haloxyfop from 26.5 to 71.3 g ha −1 . Sequencing the CT domain of the ACCase gene from resistant plants of different populations confirmed the presence of previously known mutations Ile1781Leu and Gly2096Ala. Amino acid substitution at the 2096 position conferred a greater level of resistance to haloxyfop than the substitution at the 1781 position. This study documents the first known case of field-evolved target-site resistance to ACCase-inhibiting herbicides in Australian populations of smooth barley.
Publisher: Wiley
Date: 04-2021
DOI: 10.1002/PS.6367
Abstract: Gene lification has been shown to provide resistance to glyphosate in several weed species, including Hordeum glaucum populations in South Australia. The stability of 5‐enolpyruvylshikimate‐3‐phosphate synthase ( EPSPS ) gene copies in resistant populations in the presence or absence of glyphosate selection has not been determined. Applying glyphosate to a cloned plant resulted in an increase in resistance and EPSPS copy number in the progeny of that plant compared to the untreated clone. The LD 50 (herbicide concentration required for 50% mortality) increased by 75% to 79% in the progeny of the treated clones compared to the untreated in both populations (YP‐17 and YP‐16). EPSPS copy number estimates were higher in treated in iduals compared to untreated in iduals with an average of seven copies compared to six in YP‐16 and 11 compared to six in YP‐17. There was a positive correlation ( R 2 = 0.78) between EPSPS copy number and LD 50 of all populations. EPSPS gene copy number and resistance to glyphosate increased in H. glaucum populations under glyphosate selection, suggesting the number of EPSPS gene copies present is dependent on glyphosate selection. © 2021 Society of Chemical Industry.
Publisher: Wiley
Date: 09-2017
Publisher: International Society of Communication and Development Between Universities (ISCDBU)
Date: 04-2020
Publisher: Wiley
Date: 25-04-2023
DOI: 10.1002/PS.7498
Abstract: Annual sowthistle is a weed that is difficult to control in lentil crops in southern Australia due to a lack of herbicide options, widespread herbicide resistance and prolific production of highly mobile seed. This study investigates herbicide resistance in annual sowthistle in the Mid‐North (MN) and Yorke Peninsula (YP) regions of South Australia, identifies and characterizes the mechanisms of acetolactate‐synthase (ALS)‐inhibitor resistance in this hidiploid species, and combines this with analyses of population structure and gene flow. ALS‐inhibitor‐resistant annual sowthistle is widespread across the YP and MN of South Australia and is associated with a variety of Proline‐197 mutations of the ALS gene, including leucine, alanine, arginine, serine, threonine and histidine. These mutations were found in different combinations on either of the two copies of the ALS gene. An additional 200 tissue s les were collected from across a single field on the YP and the ALS gene was sequenced for all these in iduals. Different ALS‐inhibitor resistance profiles were evident between mutation combinations and within mutation combinations, possibly mediated by differing subgenome assortment of the mutations, or altered gene experession of the two ALS homeologs. Population genetics analysis showed evidence of long‐distance dispersal, resulting in highly mobile resistance genes, and multiple instances of resistance mutation evolution. Continuing selection of Sonchus oleraceus populations with ALS‐inhibiting herbicides has resulted in the accumulation of additional mutations within the ALS gene. New practices to control herbicide‐resistant S. oleraceus should be examined, and control should focus on reducing seed set and dispersal to prevent the spread of emerging cases of resistance. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Publisher: Wiley
Date: 15-02-2017
DOI: 10.1002/PS.4501
Abstract: Acetyl coenzyme-A carboxylase (ACCase) and/or acetolactate synthase (ALS) inhibitor resistance has been identified by herbicide resistance screening in eight populations obtained from cropping regions of South Australia. This study aimed to quantify the level of resistance and characterise the molecular basis of resistance to ACCase and ALS inhibitors in these H. glaucum populations. H. glaucum populations from the Upper-North region were highly resistant (resistance index RI > 12) to the aryloxyphenoxypropionate (APP) herbicides quizalofop and haloxyfop and less resistant (RI = 2-12) to cyclohexanedione (CHD) herbicide clethodim, and some Mid-North populations had a low level of resistance (RI = 2-6) to the sulfonylurea (SU) herbicide mesosulfuron. Gene sequencing confirmed the presence of Ile-1781-Leu, Ile-2041-Asn and Gly-2096-Ala mutations in the ACCase gene, with no mutation found in the ALS gene. The use of the known metabolic inhibitor malathion in combination with mesosulfuron enhanced the activity of this herbicide. These populations were also susceptible to SU herbicide sulfometuron. This study has documented APP-to-CHD herbicide cross-resistance, the first case of ACCase inhibitor resistance due to Ile-2041-Asn mutation, and characterised the resistance to ALS inhibitors in H. glaucum. Resistance to ACCase inhibitors is due to a target-site mutation. The reversal of SU resistance by malathion and susceptibility to sulfometuron suggests that non-target-site mechanisms confer resistance to ALS inhibitors. © 2016 Society of Chemical Industry.
Publisher: Wiley
Date: 11-2017
Publisher: Springer Science and Business Media LLC
Date: 12-02-2020
DOI: 10.1186/S42269-020-0277-5
Abstract: Continual application of herbicides for flaxleaf fleabane control readily results in the evolution of herbicide resistance. Flaxleaf fleabane has evolved resistance to different modes of action herbicides in many countries. Due to the comprehensive geographical distribution of flaxleaf fleabane in Australia, it was classified as a cosmopolitan weed and it therefore has no specific climatic requirement. The high percentage of polymorphisms in the s les of the susceptible population (79.8%, 75%) suggests that susceptible populations of flaxleaf fleabane, even within one site, originated from a number of parents. However, the percentage of polymorphism in the resistant populations (51.5%, 66.8%) suggests that resistant populations of flaxleaf fleabane within one site could have originated from fewer parents. In addition, any site containing resistant and susceptible populations of flaxleaf fleabane may have been populated by a large number of parents, evidenced by the relatively high percentage of polymorphisms detected by lified fragment length polymorphism (AFLP) analysis (86.5%). Despite the large geographic distances between collection locations, populations from across states clustered in several groups showing a close genetic relationship among these populations over these large distances. These high levels of genetic ersity within and between populations confirmed in the sequencing of enolpyruvylshikimate-3-phosphate above support the results of AFLP studies and gave the author more confidence to report the genetic ersity seen within and between population studies. To prevent further resistance spread, flaxleaf fleabane management in infested areas should focus on decreasing seed movement from resistant sites as well as reducing the selection pressure for resistance to glyphosate by adopting alternative management strategies.
Publisher: Cambridge University Press (CUP)
Date: 30-10-2018
DOI: 10.1017/WSC.2017.67
Abstract: Populations of rigid ryegrass suspected of resistance to trifluralin due to control failures exhibited varying levels of susceptibility to trifluralin, with 15 out of 17 populations deemed resistant ( % plant survival). Detailed dose–response studies were conducted on one highly resistant field-evolved population (SLR74), one known multiply resistant population (SLR31), and one susceptible population (VLR1). On the basis of the dose required to kill 50% of treated plants (LD 50 ), SLR74 had 15-fold greater resistance than VLR1, whereas, the multiply resistant SLR31 had 10-fold greater resistance than VLR1. Similarly, on the basis of dose required to reduce shoot biomass by 50% (GR 50 ), SLR74 had 17-fold greater resistance than VLR1, and SLR31 had 8-fold greater resistance than VLR1. Sequencing of the α-tubulin gene from resistant plants of different populations confirmed the presence of a previously known goosegrass mutation causing an amino acid substitution at position 239 from threonine to isoleucine in resistant population SLR74. This mutation was also found in 4 out of 5 in iduals in another highly resistant population TR2 and in 3 out of 5 in iduals of TR4. An amino acid substitution from valine to phenylalanine at position 202 was also observed in TR4 (3 out of 5 plants) and TR2 (1 out of 5 plants). There was no target-site mutation identified in SLR31. This study documents the first known case of field-evolved target-site resistance to dinitroaniline herbicides in a population of rigid ryegrass.
No related grants have been discovered for Jenna Malone.