To explore the pathogenicity differentiation and variability of a Verticillium dahliae population from cotton in southern Xinjiang, 36 representative strains were collected and the pathogenicity types determined on the basis of differential host tests and PCR assays. The results of differential host tests inoculations showed that strong, moderate, and low pathogenicity strains occupied 75.0%, 11.1%, and 13.9% of total examined strains, respectively, which was different from a 2004 investigation showing 14.3%, 45.7%, and 40.0%, respectively. Results of a special PCR primer (ND1/ND2 and D1/D2) assay showed that the defoliating and non-defoliating strains occupied 33.3% and 66.7%, of total examined strains, respectively. Generally, the severity of cotton infection by the defoliating strains was higher than in non-defoliating strains, and the corresponding average index was 43.8 and 31.8, respectively. Defoliating symptoms appeared in cotton infected by defoliating and non-defoliating strains. Thus, the defoliation is not only related with the pathogenicity and pathotype of Verticillium dahliae, but also with the resistance of cotton cultivars.%采用鉴别寄主法和特异性引物PCR检测技术对采自新疆南部(南疆)棉区的36个棉花黄萎病菌菌系进行检测,以期明确其病原种群致病性分化及变异情况.鉴别寄主法测定结果显示:供试菌系中致病性强、中、弱的菌系分别为27个、4个和5个,各占75.0％,11.1％和13.9％.特异性引物(NDl/ND2和D1/D2 )PCR检测结果显示,供试36个菌系中落叶型菌系12个,占33.3％；非落叶型菌系24个,占66.7％.经统计,落叶型菌系的致病力明显高于非落叶型菌系,其平均病指分别为43.8和31.8.接种试验证明,无论落叶型菌系和非落叶型菌系,接种后都可产生落叶症状,但落叶的情况有明显差别,落叶症状的轻重不仅与菌系的致病类型有关,还与棉花品种的抗病性密切相关.
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