稻白叶枯病菌不同毒力单细胞系互作关系及田间自然群体毒力组成初析

 稻白叶枯病菌不同毒力的单细胞系混合组配后的致病力随着不同毒力菌所占的比例、彼此之间及与寄主之间的相互作用而发生相应变化;同一病田不同病株分离菌以及同一叶片不同叶位段分离菌,均存在致病力的分化;表明稻白叶枯菌在同一块田、甚至同一病叶上都存在不同的毒力细胞。稻株发病程度,是在一定生态条件下,不同毒力的多细胞入侵和协同互作的结果。所以采用"段叶沙培切口取菌胶"法所得的分离株,是含不同毒力细胞的混合体。测定一定数量的此类菌株的致病型分化,即是对田间病菌自然群体毒力组成的表型反应。
来自同一田块的36株分离菌的致病型测定结果与从48县采集的208个菌株所测定的结果非常一致,因此,对一块稻田的病菌的毒力分化测定,可以作为对相似生态条件下的广大稻区病菌自然群体毒力组成监测的参考。

PRELIMINARY ANALYSIS OF THE INTERACTION BETWEEN MONO-CELL CLONES WITH DIFFERENT VIRULENCE AND THE VIRULENT COMPOSITION OF A NATURAL POPULATION OF Xanthomonas oryzae pv. oryzae IN A RICE FIELD

The results of inoculating the mixtures of mono cell clones with different virulence of Xanthomonas oryzae pv. oryzae on the differential varieties showed that the pathogenicity of mixtures was changed in a different degree as the ratio of different mono cell clones change, reciprocity of different virulence mono cell clones and reciprocity between mono cell clones and the hosts. The result of virulence of strains of Xanthomonas oryzae pv. oryzae isolated from the same rice field revealed a lot of variability in the isolates from different infected plants and different parts of an infected leaf. It is suggested that the different virulent cells existed in a single field even in a single leaf. Therefore the cultures isolated must be a mixture with the variant cells and their pathotypes reflected the virulent composition of a natural population in a rice growing area. The pathotypes of 36 strains isolated from a single rice field were very similar to the 208 strains isolated from 48 counties, it could be the reference for investigating the variation of a natural population of Xanthomonas oryzae pv. oryzae in the rice growing area.