Seed treatment with the fungicide fluopyram limits cotyledon infection by <i>Leptosphaeria maculans</i> and reduces blackleg of canola

Peng, Gary; Liu, Xunjia; McLaren, Debra L.; McGregor, Linda; Yu, Fengqun

doi:10.1080/07060661.2020.1725132

Cited by 16 publications

(17 citation statements)

References 21 publications

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“…). This contrasts with other countries such as Canada, where fungicides for blackleg control have been shown to give limited yield returns and therefore are not used extensively (Zhang and Fernando 2018; Peng et al 2020). An alternative explanation is the potential lack of screening for fungicide resistance in other countries as well as the differences in methods being used.…”

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confidence: 92%

Fungicide sensitivity and resistance in the blackleg fungus,

Wouw

Scanlan

Marcroft

et al. 2021

Crop & Pasture Science

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Fungicide use has become a fundamental part of many crop protection systems around the world, including to control blackleg disease on canola (Brassica napus L.). In Australia, most canola growers routinely apply at least one fungicide, and potentially multiple fungicides with different modes of action, in a single growing season. There is evidence for the emergence of fungicide resistance in Leptosphaeria maculans, the causal agent of blackleg disease, to the demethylation inhibitor (DMI) class of fungicides in Australia. However, it is not known whether resistance exists towards other chemical classes such as the succinate dehydrogenase inhibitors (SDHI). In this work, 397 samples were screened for resistance towards seven fungicide treatments in stubble-borne L. maculans populations collected from eight canola-growing agro-ecological regions of Australia from 2018 to 2020, a time frame that bridges the introduction of new chemicals for blackleg control. We confirmed that DMI resistance in L. maculans is pervasive across all of the sampled canola-growing regions, with 15% of fungal populations displaying high levels (resistance scores >0.5) of resistance towards the DMI fungicides. Although resistance to newly introduced SDHI fungicides was low, we found evidence of positive cross-resistance between established DMIonly fungicides and a newly introduced combined DMI and quinone outside inhibitor fungicide, suggesting that the efficacy of the latter may be limited by widespread DMI resistance. Proactive surveillance, as performed here, may provide a means to avoid the rapid loss of fungicide efficacy in the field.

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confidence: 92%

Fungicide sensitivity and resistance in the blackleg fungus,

Wouw

Scanlan

Marcroft

et al. 2021

Crop & Pasture Science

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“…Fungicide resistance has already been identified in Australia, where L. maculans populations show sensitivity to fluquinconazole (Van de . Fluopyram seed treatment tested in Canada inhibited cotyledon infection and substantially reduced the disease severity on a susceptible cultivar (Peng et al 2020). The same research tested fluopyram on a resistant cultivar, but disease severity remained low with or without fluopyram.…”

Section: Blackleg Disease Managementmentioning

confidence: 97%

Sustainability on the farm: breeding for resistance and management of major canola diseases in Canada contributing towards an IPM approach

Dolatabadian

Cornelsen

Zou

et al. 2021

Canadian Journal of Plant Pathology

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Genetic diversity is vital for the survival of any population. If humans were all the same, a single strain of a nasty flu virus, like COVID-19, could wipe us all out! In plants, genetic diversity plays a similar role. The variation in the type and number of resistance gene(s) between individuals can cause the difference between surviving a disease or not. Studies on genetic diversity will lead to the identification of novel disease-resistance genes. Canola (Brassica napus L.) is an economically and nutritionally important oilseed worldwide. Several serious diseases, including blackleg, clubroot, sclerotinia stem rot, and verticillium stripe, threaten canola production in Canada and worldwide. Traditional methods are not enough for effective control of these diseases. Therefore, the ideal approach is to optimize and utilize the resistance genes found in different B. napus cultivars. With the advent of next-generation sequencing and the development of genomics and molecular genetics techniques, it is now possible to rapidly identify and apply resistance genes. This paper reviews current information about disease-resistance genes identified in B. napus cultivars, mapping and cloning, their importance, role and function, and their association with plant disease resistance and application in resistance breeding. The feasibility of using current resistance sources in Canadian cultivars for developing new disease-resistant cultivars is also discussed. Sustainability of a farm and an agricultural system could be maintained by breeding for disease resistance, including the resistant varieties and incorporating other integrated pest management strategies along with it.

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“…4A). Two most prevalent races, AvrLm2, 3,5,6,9,10 and AvrLm2,4,5,6,7,10,collectively accounted for about 61% of the isolates. While AvrLm5, AvrLm6 and AvrLm10 were carried by all isolates, the other avirulence genes were found present in some isolates with frequency ranging from 17.5% (AvrLm1) to 64.3% (AvrLm7) (Fig.…”

Section: Snp Haplotypes In Avr Genes and Their Corresponding Protein mentioning

confidence: 99%

“…The fungal pathogen Leptosphaeria maculans, a filamentous ascomycete, is the causal agent of blackleg (phoma stem canker) of canola or oilseed rape (Brassica napus L.) that often leads to economic losses [1,2]. Sustainable canola production requires effective management of blackleg using an integrated approach, including crop rotation, fungicide seed treatment, and the development of resistant cultivars [3][4][5][6]. The use of resistant cultivars has been considered one of the most effective and economical way to control the disease.…”

mentioning

confidence: 99%

Identification of Genome-Wide DNA Variants and SNP Haplotypes Associated with Avirulence Genes of Leptosphaeria Maculans in Western Canada

Chen¹,

Peng²,

Kutcher

et al. 2020

Preprint

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BackgroundBlackleg, caused by Leptosphaeria maculans, is a serious disease of canola/ oilseed rape in many parts of the world. An integrated approach is needed to control the disease, with genetic resistance as a key component of the management strategy. Towards this goal, a reliable approach for L. maculans race structure assessment becomes essential to gain understanding of the frequency of avirulence genes and race groups of the pathogen, and provide guidance for deployment of resistant canola cultivars.ResultsA total of 162 representative isolates collected in western Canada were selected for genome re-sequencing with an Illumina platform. Assembly of the short reads against the reference genome of L. maculans 'brassicae' isolate v23.1.3 led to the discovery of 21,016 DNA variants (SNPs and InDels), 93% SNPs and 7% InDels, with a transition/transversion (Ts/Tv) ratio of 3.1 genome wide. InDels occurred mainly in GC-blocks and the Ts/Tv ratio of SNPs in AT-blocks was > 2 times higher than that in GC-blocks. The number of variants were positively correlated with supercontig size, GC-block size and gene numbers. DNA variants in most avirulence genes were SNPs, except a deletion in AvrLm1. The number of SNPs varied from 1–2 in AvrLm2, AvrLmJ1-5-9, AvrLm6, AvrLm10A, AvrLm10B and AvrLm11, 8 in AvrLm3 and 38 in AvrLm4-7. This study is the first report of triallelic SNPs in AvrLm2 and AvrLm4-7, and premature STOP codons in AvrLm4-7. Nine SNP haplotypes were identified in AvrLm4-7, however, only 2 ~ 3 haplotypes occurred in other avirulence genes, and in total 47 haplotype groups were identified from the isolates. The 47 SNP haplotype groups were translated into 44 protein haplotype groups and then isolates of L. macualns collected in western Canada were classified into10 races.ConclusionIn this study, we document the shortcoming of inferring races from SNP genotyping, and propose the use of SNP haplotyping for more reliable and informative analysis of L. maculans race structure.

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Seed treatment with the fungicide fluopyram limits cotyledon infection by Leptosphaeria maculans and reduces blackleg of canola

Cited by 16 publications

References 21 publications

Fungicide sensitivity and resistance in the blackleg fungus,

Fungicide sensitivity and resistance in the blackleg fungus,

Sustainability on the farm: breeding for resistance and management of major canola diseases in Canada contributing towards an IPM approach

Identification of Genome-Wide DNA Variants and SNP Haplotypes Associated with Avirulence Genes of Leptosphaeria Maculans in Western Canada

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