Prevalence of pathogenicity groups of<i>Leptosphaeria maculans</i>in western Canada and North Dakota, USA

Chen, Yu; Fernando, W. G. Dilantha

doi:10.1080/07060660609507331

Cited by 46 publications

(47 citation statements)

References 27 publications

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“…& de Not., the cause of blackleg disease or phoma stem canker of Brassica spp., have been observed in western Canada (Chen & Fernando, 2006;Kutcher et al, 2007). This has been attributed to the adaptation of the pathogen to varieties of canola with high levels of genetic resistance to the disease (Kutcher et al, 2007), similar to that which occurred in France (Rouxel et al, 2003a) and in Australia (Li et al, 2003;Sprague et al, 2006).…”

Section: Introductionmentioning

confidence: 68%

“…The fact that an isolate virulent on LepR3 was obtained from western Canada, indicates that this resistance gene may be overcome relatively rapidly if widely deployed. It is noteworthy that the three isolates in this study that did not carry AvrLm2, and were virulent to Rlm2, were collected from southern Manitoba, where isolates classified as PG3 and PG4 have been obtained (Chen & Fernando, 2006;Kutcher et al, 2007). PG3 and PG4 isolates are virulent on 'Glacier' (Rlm2 and Rlm3), which indicates they do not carry AvrLm2.…”

Section: Discussionmentioning

confidence: 97%

“…Isolates are classified as: PG2 -resistant reaction on both varieties; PG3 -'Quinta' resistant, 'Glacier' susceptible; PGT -'Quinta' susceptible, 'Glacier' resistant; or PG4 -both varieties susceptible (Mengistu et al, 1991). Isolates of L. maculans from Alberta, Saskatchewan and Manitoba in western Canada and from North Dakota, USA have recently been classified into various PGs (Chen & Fernando, 2006;Kutcher et al, 2007). The PG classification system has been useful as a tool to recognize changes in pathogenicity of the pathogen population since the early 1990s in western Canada.…”

Section: Introductionmentioning

confidence: 99%

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Frequency of avirulence genes inLeptosphaeria maculansin western Canada

Kutcher

Balesdent²,

Rimmer

et al. 2010

Canadian Journal of Plant Pathology

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Changes in pathogenicity of populations of Leptosphaeria maculans, the cause of blackleg disease of canola and other Brassica spp., have been observed in western Canada. These changes in the population are believed to have resulted from the use of specific resistance (Rlm) genes in Brassica spp., many of which have only recently been identified. We determined the frequency of 10 avirulence alleles for 96 isolates of L. maculans collected between 1997 and 2005 from Alberta, Saskatchewan and Manitoba, Canada from infested canola stubble in field plots or farmers' fields. Cotyledon interaction phenotypes were scored after inoculation of each isolate on a differential set of Brassica varieties or lines carrying the known resistance genes LepR3 and Rlm1 to Rlm10, except for Rlm8. The avirulence (AvrLm) alleles present in each isolate were inferred from the data. Due to the presence of confounding resistance genes in the host differentials, AvrLm1 and AvrLm2 could not be determined in nine of the isolates, AvrLm6 in two isolates and AvrLepR3 in 49. Based on the number of isolates in which the avirulence genes were confirmed, AvrLm1 was detected in 46.0% and AvrLm9 in 60.4% of the isolates in this collection. A high proportion of isolates carried AvrLm2 (96.6%) and AvrLepR3 (97.9%), and all isolates carried AvrLm6 and AvrLm10. The proportion of L. maculans isolates carrying AvrLm3, AvrLm4, AvrLm5 and AvrLm7 was much lower and varied between 10.4 and 29.2%. In total, 16 races of L. maculans were identified based on 10 avirulence alleles, with seven races accounting for 89.7% of the isolates. Information on the avirulence frequency in the pathogen population will be useful for development of resistance management strategies to control blackleg disease in B. napus oilseed rape in western Canada.Résumé: Des changements dans la pathogénicité des populations de Leptosphaeria maculans, l'agent responsable de la maladie de la Nécrosse du collect chez le canola ainsi que chez d'autres Brassica spp., ont été observés dans l'Ouest canadien. On croit que ces changements résultent de l'utilisation de gènes spécifiques de résistance (Rlm) chez Brassica spp., dont plusieurs n'ont été que récemment identifiés. Nous avons déterminé la fréquence de 10 allèles d'avirulence pour 96 isolats de L. maculans collectés, de 1997 à 2005, en Alberta, en Saskatchewan et au Manitoba, sur du chaume de canola infecté provenant de parcelles expérimentales et de champs cultivés. Les phénotypes d'interaction ont été notés sur cotyiédons après inoculation de chaque isolat sur un groupe différentiel de variétés de Brassica ou de lignées portant les gènes de résistance connus LepR3 et Rlm1 à Rlm10, sauf Rlm8. Les allèles d'avirulence (AvrLm) présents dans chaque isolat ont été déduits des données. Étant donnée la présence simultanèe de gènes de résistance dans certains hôtes différentiels, AvrLm1 et AveLm2 n'ont pu être confirmés dans neuf des isolats, AvrLm6, dans deux et AvrLepR3, dans 49. En se basant sur le nombre d'isolats dans lesquels la présence de...

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Section: Introductionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Frequency of avirulence genes inLeptosphaeria maculansin western Canada

Kutcher

Balesdent²,

Rimmer

et al. 2010

Canadian Journal of Plant Pathology

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“…All isolates collected from Manitoba and Saskatchewan in 1991 belonged to the PG2 group (Kutcher et al 1993). PG2 isolates remained the most common isolates found in western Canada until the year 2000, but new PGT isolates were identified in isolates collected between 1998 and 2000, and a new PG3 isolate was detected in Manitoba in 1999 (Fernando and Chen 2003;Chen and Fernando 2006;Rimmer 2006 Liban et al (2016). Since 2012, blackleg incidence in Manitoba and Alberta were more than 10%.…”

Section: Blackleg Resistance Erosion In Canadamentioning

confidence: 99%

Insights into fighting against blackleg disease of Brassica napus in Canada

Zhang

Fernando

2018

Crop Pasture Sci.

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Abstract. Blackleg disease, caused by the ascomycete fungal pathogen Leptosphaeria maculans, is a devastating disease of canola (Brassica napus) in Australia, Canada and Europe. Although cultural strategies such as crop rotation, fungicide application, and tillage are adopted to control the disease, the most promising disease control strategy is the utilisation of resistant canola varieties. However, field populations of L. maculans display a high evolutionary potential and are able to overcome major resistance genes within a few years, making disease control relying on resistant varieties challenging. In the early 1990s, blackleg resistance gene Rlm3 was introduced into Canadian canola varieties and provided good resistance against the fungal populations until the early 2000s, when moderate to severe blackleg outbreaks were observed in some areas across western Canada. However, the breakdown of Rlm3 resistance was not reported until recently, based on studies on R genes present in Canadian canola varieties and the avirulence allele frequency in L. maculans populations in western Canada. The fact that Rlm3 was overcome by the evolution of fungal populations demands canola breeding programs in Canada to be prepared to develop canola varieties with diversified and efficient R genes. In addition, frequent monitoring of fungal populations can provide up-to-date guidance for proper resistance genes deployment. This literature review provides insights into the outbreaks and management of blackleg disease in Canada.

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“…It is possible that the increased blackleg incidence and severity reflect a breakdown in cultivar resistance or at least a gradual erosion of resistance with time. Changes in blackleg pathogen virulence have been observed with high disease severity reported in some cases and typically this is associated with shortened rotations, especially where the same sources of resistance are used (Keri et al 2001;Fernando and Chen 2003;Chen and Fernando 2006;Kutcher et al 2007Kutcher et al , 2011a.…”

Section: Blackleg Disease Levelsmentioning

confidence: 99%

Canola rotation frequency impacts canola yield and associated pest species

et al. 2015

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G. 2015. Canola rotation frequency impacts canola yield and associated pest species. Can. J. Plant Sci. 95: 9Á20. Canola (Brassica napus L.) production has been steadily increasing in western Canada. Here we determine the effect of canola rotation frequency on canola seed yield, quality and associated pest species. From 2008 to 2013, direct-seeded experiments involving continuous canola and all rotation phases of wheat (Triticum aestivum L.) and canola or field pea (Pisum sativum L.), barley (Hordeum vulgare L.) and canola were conducted at five western Canada locations. Fertilizers, herbicides, and insecticides were applied as required for optimal production of all crops. Canola rotation frequency did not influence canola oil or protein concentration or the level of major (composition 1%) seed oil fatty acids. High canola yields were associated with sites that experienced cooler temperatures with adequate and relatively uniform precipitation events. For each annual increase in the number of crops between canola, canola yield increased from 0.20 to 0.36 Mg ha (1 . Although total weed density was not strongly associated with canola yield, decreased blackleg disease and root maggot damage were associated with greater canola yields as rotational diversity increased. Long-term sustainable canola production will increase with cropping system diversity.Key words: Blackleg, Delia spp., direct seeding, Leptosphaeria maculans, no-till, oilseed rape, root maggots, rotational diversity, weed populations Harker, K. N., O'Donovan, J. T., Turkington, T. K., Blackshaw, R. E., Lupwayi, N. Z., Smith, E. G., Johnson, E. N., Gan, Y., Kutcher, H. R., Dosdall, L. M. et Peng, G. 2015. La fre´quence des assolements de canola influe sur le rendement de la culture et sur les ravageurs qui s'y associent. Can. J. Plant Sci. 95: 9Á20. La production de canola (Brassica napus L.) n'a cesse´d'augmenter dans l'Ouest canadien. Les auteurs se sont inte´resse´s aux conse´quences de la fre´quence des assolements de canola sur le rendement grainier de cette culture, sur sa qualite´et sur les ravageurs qui y sont associe´s. De 2008 a`2013, ils ont effectue´des expe´riences de semis directs pour la monoculture de canola et les assolements de ble( Triticum aestivum L.) et de canola ou de pois de grande culture (Pisum sativum L.), d'orge (Hordeum vulgare L.) et de canola a`cinq endroits, dans l'ouest du Canada. Les engrais, les herbicides et les insecticides ont e´te´applique´s au besoin afin que chaque culture donne un rendement optimal. La fre´quence des assolements de canola ne modifie pas la concentration en huile ou en prote´ines du canola, ni la teneur des principaux (composition 1 %) acides gras pre´sents dans l'huile. Le rendement du canola est plus e´leve´aux endroits ou`la tempe´rature est plus fraıˆche et les pre´cipitations, suffisantes et relativement uniformes. Pour chaque hausse annuelle du nombre de cultures dans l'assolement, le rendement du canola augmente de 0,20 a`0,36 Mg par hectare. Bien que la densite´de peuplement globale des a...

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Prevalence of pathogenicity groups ofLeptosphaeria maculansin western Canada and North Dakota, USA

Cited by 46 publications

References 27 publications

Frequency of avirulence genes inLeptosphaeria maculansin western Canada

Frequency of avirulence genes inLeptosphaeria maculansin western Canada

Insights into fighting against blackleg disease of Brassica napus in Canada

Canola rotation frequency impacts canola yield and associated pest species

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