Analyses of The pathogenic race mutation In Magnaporthe grisea

为了了解日本稻瘟病菌的遗传背景，采用DNA指纹图谱和电泳核型分析方法对日本稻瘟病菌进行了鉴定。利用MGR 586和pMG 60 I5的DNA指纹图谱分析，将7个日本鉴别菌株和24个田间分离物聚为5个克隆谱系。对142个菌株的核型分析表明，JBLA-K 04和JBLB-K33是两个主要的克隆谱系。这些结果表明，日本稻瘟病菌致病性的变异是由包括染色体重排在内的突变引起的。这种核型突变在脉冲场分离的核型中产生一条额外的染色体带。这种突变的特点是发生在12.5%的自发性高， ...更多信息 通过从与野生型菌株中的带IIIa共迁移的染色体带IIIb中缺失约1 Mb DNA，以单向产生额外带。从该菌株中克隆并分析了rDNA，该基因编码rRNA，该rRNA被报道是酵母中染色体重排的原因。该基因位于带IIIb上，簇的单位大小约为8 kb。突变体和野生型的rDNA簇大小均在400 kb左右。因此，rDNA簇集不是引起核型突变的原因。利用rDNA检测JBLA-K 04田间分离株的染色体大小变异。结果表明，在田间分离株中未检测到主要的大小变异，表明该簇与染色体重排无关。对水稻品种K59的无毒性进行了遗传分析，发现无毒性：毒性=21：8的分离。少

We characterized Japanese rice blast fungus by means of DNA fingerprinting and electrophoretic karyotyping in order to know their genetic backgrounds. Seven Japanese differential strains and 24 field isolates were clustered into 5 clonal lineages, in the DNA fingerprinting analyses using MGR586 and pMG60I5. In JBLA-K04, one of the lineages, all field isolates from various pathogenic races were included, In these field isolates, a relationship between karyotypes and pathogenic races Further analyses using 142 strains, revealed that two major clonal lineages, JBLA-K04 and JBLB-K33. These results suggested that the variation of pathogenicity among Japanese rice blast fungus were derived from mutations including chromosomal rearrangements.We also analyzed a karyotypic mutation in Magnaporthe grisea strain Ina168. This karyotypic mutation generates one additional chromosomal band in the pulsed field separated karyotype. This mutation was characterized to occur at a high rate of 12.5% sponta … More neously, in uni-direction to generate the extra band, by deleting app. 1Mb DNA from a chromosomal band IIIb which comigrates with band IIIa in the wild type strain. rDNA, the gene encodes rRNA which reported to be causes of chromosomal rearrangement in yeasts, were cloned from the strain and analyzed. The gene located on band IIIb, and unit size of the cluster was revealed to be app. 8kb. The size of the rDNA cluster was app. 400kb in both mutant and wild type. We concluded that rDNA cluster was not the cause of the karyotypic mutation. The rDNA was used for detecting chromosomal size variation among field isolates belong to JBLA-K04. We could not detect major size variation, indicating that the cluster would not be responsible for the chromosomal rearrangement in field isolates.A cross-system utilizing Japanese strain was constructed for genetic analyses of avirulrence genes. A genetic analysis of avirulence toward rice variety K59 was performed, and revealed segregation of avirulence : virulence =21 : 8. Less