稻瘟病菌微波诱发突变体的分析*

通过诱变获得突变体是研究稻瘟病菌变异机制的基础。本文用微波炉对稻瘟病菌分生孢子进行低强度短时间处理获得了一批形态发育和致病性突变体,并对它们进行了分析。突变体1-40-271菌落呈白色,产孢与萌发均正常,但萌发后即便在人工疏水表面上也不能形成附着胞,且丧失了致病性;突变体2-20-6菌落呈黄色,孢子萌发率为1%,萌发的孢子其附着胞形成率仅为0.01%,致病性减弱;突变体2-30-3菌落呈黄色,形成的附着胞大部分不正常,但致病性正常。Rep-PCR指纹分析发现,突变体2-20-6和2-30-3比其相应野生型少1条带,而突变体1-40-271与其野生型比较没有变化,说明微波可能造成稻瘟病菌基因组DNA缺失或点突变而发生变异。继代分析表明微波处理获得的稻瘟病菌形态和致病性突变体是稳定的。

MUTANTS OF MAGNAPORTHE GRISEA GENERATED BY MICROWAVE IRRADIATION

Mutant generation is the basic work to study mutation mechanism of Magnaporthe grisea, the devastating fungal pathogen of the rice blast disease. A large scale of mutants were generated through low dosage of microwave irradiation, in which several morphology and pathogenicity mutants were obtained. A white colony mutant, 1-40-271, was normal in sporulation and spore germination, but defective in appressorium development and totally lost in pathogenicity. One yellow colony mutant, 2-20-6, decreased to 1% in sporulation and to 0.01% in appressorium formation compared with the wild type, which resulted in its weaker pathogenicity. Another yellow colony mutant, 2-30-3, was abnormal in appressorium development, but its pathogenicity was not affected. In Rep-PCR DNA fingerprinting, no difference was observed in mutant 1-40-271, but one band was absent in mutants 2-20-6 and 2-30-3 compared with their wild type respectively, which suggested that the mutagenesis in these mutants might attribute to DNA deletion or locus mutation. Continuous culture of these mutants demonstrated that the morphology and pathogenicity mutation induced by microwave irradiation was stable.