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

(1)M.本研究利用云南分离的两个稻瘟病菌菌株进行杂交，对Avr-pii、Avr-pia、Avr-Hattan 3三个无毒基因进行了研究。这些无毒基因被映射到真菌的遗传图谱上。沿着Avr-Happen 3构建了一个长度为600 kb的BAC重叠群。另一方面，Avr-pia也被鉴定为来自日本分离物和罕见的两性花分离物Guy 11之间的杂交。利用寄主特异性突变体，分离到一个与Avr-pia位点紧密连锁的DNA片段，命名为PM-01。发现其中一个含有PM-01片段的粘粒克隆能够互补宿主特异性突变，表明该克隆含有Avr-pia基因。(2)M.从M.分别命名为Rhm 52、Rhm 54和Mhm 11。其中Rhm 54与N. crassa，并通过MMS处理诱导M.稻瘟病菌细胞

(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.