Blackleg, which is caused by the fungus Leptosphaeria maculans (L. maculans), is a major disease of canola in western Canada and worldwide. Long-term use of one source of resistance could cause the breakdown of its effectiveness. Therefore, appropriate use of R genes is very important, and knowledge about the distribution of avirulence genes is a prerequisite for effectively deploying resistance. Of the 14 avirulence genes identified in L. maculans, AvrLm5 and AvrLm9 were recognized as the two alleles of the same gene based on two single nucleotide polymorphisms, C⁸⁵T and G¹⁶⁴A/C. In this study, a specific marker was developed to identify AvrLm5 and AvrLm9 based on two single nucleotide polymorphisms, C⁸⁵T and G¹⁶⁴A/C, which are responsible for the function of AvrLm9. The specific marker can be used to discriminate the AvrLm9 from avrLm9 accurately in L. maculans isolates, which is consistent with inoculation tests in isolates without AvrLm4-7. This specific marker was used to screen 1229 isolates collected from fields in the years 2014 through 2016 in Manitoba. From 68 to 84% of the isolates were found to contain the AvrLm9 allele; while 4–7% of them were avirulent on the variety Goéland with Rlm9 loci. Furthermore, no isolates having both AvrLm9 and AvrLm7 were detected using a cotyledon test, while 67% to 84% of isolates contained both avirulence genes via PCR detection, implying suppression of AvrLm9 by AvrLm7. In addition, avirulence gene profiles of the other 10 avirulence alleles were examined with the 1229 isolates using cotyledon tests or PCR amplifications. Taken together, this research enables the fast identification of AvrLm5/9, provides the Avr genes’ landscape of western Canada and elaborates the relationship between AvrLm9 and AvrLm7 using isolates from grower fields.

黑腿病是由真菌Leptosphaeria maculans（L. maculans）引起的，是加拿大西部和世界范围内双低油菜籽的主要病害。长期使用一种抗药性可能会导致其有效性下降。因此，正确使用R基因非常重要，关于无毒力基因分布的知识是有效部署抗性的先决条件。在鉴定的14个无毒基因的L. maculans，AvrLm5和AvrLm9被承认为基于两个单核苷酸多态性，C相同基因的两个等位基因⁸⁵ T和G ¹⁶⁴空调。在这项研究中，基于两个单独的核苷酸多态性C ⁸⁵ T和G ¹⁶⁴ A / C，开发了一种特定的标记物来鉴定AvrLm5和AvrLm9，它们负责AvrLm9的功能。特定标记物可以用来区分AvrLm9从avrLm9准确地L. maculans分离株，这与菌株接种测试，没有一致的AvrLm4-7。该特异性标记物用于筛选2014年至2016年在曼尼托巴省从田地中收集的1229株分离株。发现68至84％的分离株含有AvrLm9等位基因 而其中有4–7％在带有Rlm9基因座的Goéland品种中无毒。此外，通过子叶测试未检测到同时具有AvrLm9和AvrLm7的分离株，而67％至84％的分离株通过PCR检测同时含有两种无毒力基因，这意味着AvrLm7抑制了AvrLm9。另外，使用子叶测试或PCR扩增，用1229个分离株检查了其他10个无毒力等位基因的无毒力基因谱。总之，这项研究使的快速识别AvrLm5 / 9，提供了无毒基因加拿大西部的景观，并阐述之间的关系AvrLm9和AvrLm7使用来自种植者田地的分离株。