Abstract

Plasmodiophora brassicae Woronin, the cause of clubroot of crucifers, is now established across most of Alberta, Canada, and has become a major constraint in canola (Brassica napus L.) production. Disease control is achieved mainly by planting clubroot-resistant (CR) canola varieties. The first CR canola in Canada was released in 2009. In 2013, severe clubroot was detected on CR canola in several fields in Westlock County, Alberta, and found to be caused by a ‘new’ strain of P. brassicae termed ‘5X’. These strains have been shown to be genetically distinct from other P. brassicae strains in Alberta (‘population one’) and belong to a second population (‘population two’) of the pathogen. In this study, multiple molecular markers, specific for ‘population two’, were used to determine the occurrence of members of this population over time throughout central Alberta. Two hundred and twenty-four clubroot galls collected from 2005 to 2016 from non-CR canola varieties were examined. The presence of ‘population two’ DNA was detected at low levels in at least 47 of the galls, and it was the predominant population of P. brassicae in another 10 of the samples. These samples were found in Flagstaff County starting in 2008, Westlock County starting in 2009, the County of Vermillion River in 2011 and Red Deer County in 2014. Although relatively uncommon, members of this population were widespread, occurring at locations 168 km apart prior to the release of CR canola.

摘要

十字花科根肿病的致病菌Plasmodiophora brasicae Woronin 现已遍布加拿大艾伯塔省的大部分地区，并已成为油菜 ( Brassica napus L.) 生产的主要限制因素。病害控制主要通过种植抗根肿（CR）油菜品种来实现。加拿大的第一个 CR 油菜于 2009 年发布。2013 年，在艾伯塔省 Westlock 县的几个田地中检测到严重的根肿病，发现是由一种名为“5X”的“新”芸苔属油菜菌株引起的。这些菌株已被证明在遗传上与其他P. brasicae不同阿尔伯塔省的菌株（“种群一”）属于病原体的第二个种群（“种群二”）。在这项研究中，特定于“第二个群体”的多个分子标记被用来确定该群体成员在整个艾伯塔省中部随时间推移的出现情况。对 2005 年至 2016 年从非 CR 油菜品种收集的 224 个根肿块进行了检查。在至少 47 个虫瘿中检测到低水平的“第二种群”DNA，它是芸苔藓的主要种群在另外 10 个样本中。这些样本从 2008 年开始在弗拉格斯塔夫县、从 2009 年开始在韦斯特洛克县、2011 年在朱红河县和 2014 年在红鹿县发现。虽然相对不常见，但这一人群的成员分布广泛，发生在相距 168 公里的地方。 CR油菜的发布。