稻瘟病菌继代培养中遗传稳定性研究

结合苗圃鉴定和ＲＡＰＤ分析，研究了稻瘟病菌继代培养过程中遗传的稳定性。结果表明，在继代培养过程中，强致病菌ＤＮＡ水平上变化较大，其致病性的变异也相当大，而弱致病菌ＤＮＡ水平上的变化较小，其致病性也无明显变异，说明强致病菌较弱致病菌更不稳定，其毒力在继代过程中有逐渐弱化的趋势，ＤＮＡ水平上的变化在一定程度上也反映了这种变异。

STUDIES ON GENETIC VARIATIONS OF MAGNAPORTHE GRISEA DURING SUCCESSIVE ASEXUAL GENERATIONS

Using characterization in nursery and RAPD assay, we studied genetic variations during successive asexual generations of Magnaporthe grisea . When strains ZA 1 and ZG 1 were cultured under successive asexual generations the high virulent pathotype strain ZA 1 was unstable, tending to weaken its virulent gradually and changed the infection spectrum. RAPD analysis of the strains from different generations showed that the changes had already taken place in their genomes but not only in their phenotypes. While the low virulent pathotype strain ZG 1 was considerably stable in the infection spectrum and at the DNA level after successive asexual culture. The results suggested that high virulent pathotype strain was unstable compared with low virulent pathotype strain and those changes can be detected by using RAPD.