四川省根肿菌的分布和生理小种及品种抗性评估

为探究四川省根肿菌Plasmodiophora brassicae分布、生理小种及品种抗性,于2014-2016年向各县(区、市)植保站问卷调研了解四川省根肿病分布,并利用Williams体系对采自四川省不同病田的22个根肿菌样进行生理小种鉴定,利用其中18个对9个普通十字花科作物品种进行室内抗性评估。结果表明,根肿病分布于四川省19市(州)89个县(区、市),占总调查数的50%。按照极高、高、中等、低、极低、无分布6个根肿病分布密度等级依次划分为23、7、11、16、32和0个县(区、市),其中11个县(区、市)根肿病病史较长,大部分根肿病极高和高密度分布以及长病史县(区、市)都在地理位置上相对集中。22个根肿菌样共鉴定出2、4、7和11号4个生理小种,其中4号为优势生理小种,占77%。四川省表现出明显生理小种地域分布差异。抗性评估发现供试品种对绝大多数供试菌都表现感病,且73%的供试组合病情指数在75以上。

Distribution and pathotype of Plasmodiophora brassicae in Sichuan and cultivar resistance evaluation

In order to investigate the distribution, pathotypes of Plasmodiophora brassicae in Sichuan and cultivar resistance, the clubroot distribution was surveyed in the plant protection stations of each county of Sichuan from 2014 to 2016. Williams system was used to identify the pathotypes of 22 P. brassicae populations collected from different infested fields in Sichuan, 18 of which were selected to evaluate clubroot resistance on nine normal cruciferous cultivars in the greenhouse. The results showed that clubroots occurred in 89 counties of 19 cities in Sichuan, accounting for 50% of counties surveyed. These counties were classified as extreme, high, moderate, low, limited clubroot distribution density and no clubroot distribution, with 23, 7, 11, 16, 32 and 0 counties felling into each category. Eleven out of 89 counties had a relatively long disease history. Moreover, most counties with extreme and high clubroot distribution density or relatively long disease history were relatively concentrated geographically. Pathotype 2, 4, 7 and 11 were identified in 22 populations. Pathotype 4 constituted for 77%, indicating that it was the dominant pathotype in Sichuan. Geographical distribution of the pathotypes was observed obviously in Sichuan. Resistance evaluation concluded that all the cultivars tested showed susceptible reactions to most of the populations tested, and 73% of the host-population combinations had a disease index higher than (or equal to) 75.