云南省烟草黑胫病菌致病力分化的研究

ON VIRULENCE DIFFERENTIATION OF THE CAUSED ORGANISM OF TOBACCO BLACK SHANK IN YUNNAN PROVINCE

将分离自云南省不同地区的２１株黑胫病菌（ＰｈｙｔｏｐｈｔｈｏｒａｎｉｃｏｔｉａｎａｅＢｒｅｄａｄｅＨａａｎ）接种烟草品种Ｋ３２６、Ｇ２８和红大，测定其对不同烟草品种的致病力。经统计分析，发现其对烟草的致病力有差异。采用菌丝块创伤和不创伤两种接种方法测定致病力的结果不同。对不同地区的黑胫病菌间的致病力以及由烟草和非烟草寄主上获得的烟草疫霉菌株的致病力进行了比较，结果表明，云南省黑胫病菌的致病力较强，由烟草上获得的烟草疫霉菌株对烟草的致病力强于非烟草菌株。实验结果还发现，供试的３个烟草品种，以Ｋ３２６对云南省烟草黑胫病菌的抗病性最强，红大品种较感病。

Twentyone isolates of Phytophthora nicotianae Breda de Haan from diseased tobacco plants from different areas in Yunnan Province were inoculated on the seedlings of tobacco cultivars of K326, G28 and Hongda. The virulence of isolates showed obvious variation among isolates on cultivar K326 and Hongda, and no difference on G28. When the seedling stems were inoculated by disc method with or without wounded on cultivar K326, G28 and Hongda, different virulence were also observed between different inoculation methods, the symptom on wounded seedlings occured earlier and severer. A comparison of virulence of P. nicotianae isolates from tobacco and nontobacco host plants on those three tobacco cultivars showed that the isolates from tobacco cause severer disease symptom than those from nontobacco hosts, and some of nontobacco isolates and tobacco isolates from outside of Yunnan failed to infect those three cultivars tested. Of three tobacco cultivars tested, K326 was the most resistant, and Hongda was the most sensitive.