落叶型棉花黄萎病菌的致病力分化

Pathogenicity differentiation of defoliation strains of Veticillium dahliae in the cotton

为明确我国长江流域和黄河流域主要植棉省落叶型菌系的致病力差异,选用4个抗性不同的陆地棉品种银瑞361、豫棉21、冀棉228和冀棉11作为鉴别品种,在温室可控条件下,采用苗期移苗蘸根接种法,对不同植棉省32个落叶型黄萎病菌的致病性进行了测定,并根据供试菌系在鉴别品种上病情指数进行聚类分析。苗期接种14 d后,抗、感品种间的病情指数差异较大,是落叶型菌系病情指数调查的合适时间。32个落叶型菌系致病力差异显著,可分为3个类型。第Ⅰ类型只有1个菌系,致病力弱;第Ⅱ类型菌系占供试菌系的62.5%,平均病情指数为36.8,致病力中等;第Ⅲ类型菌系占供试菌系34.4%,平均病情指数52.7,致病力较强,4个鉴别品种均表现感病。研究表明来源于不同植棉省菌系的平均致病力有一定差异,且来源于同一植棉省的落叶型菌系可归属于不同的致病类型。

To compare the virulence differentiation of defoliating Veticillium dahliae strains in the main cotton-producing provinces of Yangtze and Yellow river valleys, the pathogenicity of 32 strains from ten provinces were tested using root-dip inoculation method in the process of seedling transplanting under con- trolled greenhouse conditions. Four cotton varieties, namely Yinrui 361, Yumian 21, Jimian 228 and Jimian 11, were employed as identified varieties and showed different degrees of resistance to V. dahliae. Cluster analysis of 32 strains was based on the disease indexes of the identified varieties. The results showed that the disease indexes of the resistant and susceptible varieties were significantly different at 14 d after inoculation, indicating that this time point was suitable for investigation of the disease index. The significant difference in pathogenicity was found among the 32 defoliating strains, which were divided into three pathogenic types. Cluster I included only one strain with weak pathogenicity, while, Cluster ]I was the biggest group, which showed moderate pathogenicity with an average disease index of 36.8, ac- counting for 62.5% of the total strains. The pathogenicity of the strains in Cluster HI which accounted for 34.4% of the total strains was most virulent. All of the identified varieties were susceptible to the strains, with an average disease index of 52.7. The difference in pathogenicity of the strains from diffe- rent cotton-producing provinces existed, and the pathogenicity of the strains from the same province might belong to different clusters.