江苏省稻瘟病菌有性态的研究*

用标准菌株对１９９７～１９９９年在江苏省吴江市，宜兴市、通州市、高邮市和赣榆县采集的３２５个猪瘟病菌单孢分离菌株的可育性和交配型进行了测定，结果表明江苏省稻瘟病菌菌株的育性较低，可交配率为２２．７７％，可育率仅为７．０８％。不同年份、不同地区采集的猪瘟病菌茵株的性亲和力和交配型有较大的差异，三年的交配率分别为２６．６１％、８．２６％和３３．６４％；温州地区和赣榆地区菌株的交配率相对较高，分别为２６．１５％和２５．４２％，宜兴地区菌株的交配率较低，只有１５．３８％。江苏省稻瘟病菌菌株的交配型在不同年份亦出现很大差别，１９９７年２９个可交配菌株中有２１个菌株表现为ＭＡＴ１－２ 交配型，而１９９９年３６个可交配茵株均为ＭＡＴ１－１交配型。用江苏省稻瘟病菌的可育菌株进行互交，２５个组合中只有６个组合能产生子囊壳和子囊，但均不产生子囊孢子，提示江苏省稻瘟病菌在田间产生健康有性后代的几率不大。对杂交后代的遗传学分析表明，菌株的交配型是受单基因控制的。

THE PERFECT STAGE OF MAGNAPORTHE GRISEA IN JIANGSU PROVINCE, CHINA

Three hundred and twenty-five isolates of Magnaporthe grisea collected from rice plants in Wujiang, Yaxing, Tongzhou, Gaoyou and Ganyu of Jiangsu province from 1997~1999 were tested for mating type and fertility with standard tester strains. Seventy-four tested isolates produced perithecia after mated with tester strains, in which, 48 were MAT1 -1 and 26 were MAT1-2 mating hoe. The fertile ratio of isolates from Jiangsu was 22.77% on average. Among them only 23 crosses produced ascospores and the ratio was 7.1%. But the fertile ratio showed great vacation annually, 26.61% in 1997, 8.26% in 1998 and 33.64% in 1999 respectively. In addition, the fertile ratio of tested isolates collected from different areas was also dissimiar., 26.15% and 25.42% from Tongthou and Ganyu, and only 15.38% from Yixing. Moreover, the ratio of both mating typer in fertile isolates collected from different years also changed, 21of 29 fertile isolates in 1997 were mating type MAT1-2 and all of 36 fertile isolates collected in 1999 wer MAT1-1. Furtherly, crosses were made among fertile isolates from rice plants in Jiangsu. Only 6 of 25 crosses produced perithecia and asci, but no ascospore produced. This suggest that the frequency of sexual stage occurrence of Magnaporthe grisea was very low in the rice field in Jiangsu. Genetic analysis of sexual progeny showed that the segregation ratio of MAT1-1 and MAT1-2 was 1:1, indicated the both mating type were controlled by single gene.