向日葵黄萎病菌营养亲和性及致病力分化

为进一步研究向日葵黄萎病病原菌的变异规律及不同菌株致病力差异，本研究以采自于黑龙江、内蒙古东部和西部、河北、陕西、宁夏、新疆等向13葵黄萎病发生严重的地块，并经分离纯化后得到的120株菌株为材料，开展了菌株问营养亲和性、致病力分化研究。结果表明：利用硝酸盐营养缺陷型突变体（nu）技术可将120株菌株分为3个亲和群（VCGs），3个亲和群分别有89株、13株、7株，此外，还有11株未能鉴定出亲和群。通过对3个鉴别寄主的致病力测定，120株菌株可分为3个致病类型，强致病力（Ⅰ）占7．3％，中等致病力（Ⅱ）占52．7％，弱致病力（Ⅲ）占40％，菌株致病力存在明显的差异。研究同时表明菌株问营养亲和性与地理位置没有明显的相关性，但与致病性类型具有一定的相关性。

Vegetative compatibility and pathogenicity of Verticillium dahliae isolates from sunflower

Sunflower verticillium wilt has become a severe disease in China in recent years. In order to understand the variation and differentiation of the pathogen, 120 Verticillium dahliae strains were obtained from plants which showed typical verticillium wilt symptoms collected from Heilongjiang Province, Inner Mongolia Autonomous Region, Hebei, Shaanxi Province, Ningxia Hui Autonomous Region and the Xinjiang Uygur Autonomous Region. Furthermore, vegetative compatibility, pathogenicity of these strains were analyzed. 120 strains could be classified into three vegetative compatibility groups （VCGs） based on eomplementation tests of Nitrate -non- utilizing （nit） mutants. There were 89, 13, and 7 strains in these three different VCGs. In addition, there were 11 unclassified strains. Pathogenicity differentiation of these strains of V. dahliae tested with three sunflower differential hosts was clear. The 120 strains were classified into three pathogenicity types ：7.3% strains were characterized as Type I with strong pathogenicity, 52.7% as Type Ⅱ with medium pathogenicity, 40% as Type Ⅲ with weak pathogenicity. The results indicated that there was no correlation between vegetative compatibility and geographical origin, but VCGs might be correlated with pathogenicity.