Study on the induction system of host specificity mutations in Magnaporthe grisea,: avirulence genes and recombinational repair genes

(1)稻瘟病菌无毒基因的分析利用两个云南分离物的杂交组合，研究了三个无毒基因AVR-PII、AVR-PIA、AVR-Hattan3。这些无毒基因被定位到该真菌的遗传图谱上。沿着AVR-Hitan 3构建了一个600kb的BAC重叠群。另一方面，AVR-Pia也是从日本分离物与稀有两性分离物Guy11的杂交中鉴定出来的。利用宿主特异性突变体，分离到一个与AVR-pia基因紧密连锁的DNA片段PM-01。(2)稻瘟病菌重组修复基因的分析从稻瘟病菌基因组中克隆了RAD52、RAD54和Mre11的同源基因，分别命名为Rhm52、Rhm54和Mhm11。在这些同源基因中，Rhm54与稻瘟病菌MUS-23突变体的表型互补，并且在稻瘟病菌细胞中可以被MMS诱导。

(1) Analysis of avirulence genes in M. griseaThree avirulence genes, Avr-pii, Avr-pia, Avr-Hattan3 was investigated using a cross between two Yunnang isolates. These avirulence genes were mapped onto the genetic map of the fungus. Along the Avr-Hattan 3, a BAC contig of 600kb in length was constructed. On the other hand, Avr-pia was identified also from a cross between Japanese isolate and rare hermaphloditic isolate Guy11. By utilization of the host specificity mutant, a DNA fragment named PM-01, which was tightly linked to the Avr-pia locus was isolated. One of the cosmid clone containing the PM-01 fragment was found to be able to complement the host specificity mutation, indicating that the clone containing the Avr-pia gene.(2) Analysis of recombnational repair genes in M. griseaHomologous genes for RAD52, RAD54, and MRE11 was cloned from M. grisea genome, and named Rhm52, Rhm54 and Mhm11, respectively. Among these homologs, Rhm54 was found to complement the phenotype of mus-23 mutant of N. crassa, and to be inducible by MMS treatment in M. grisea cells.