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

(1)灰稻瘟病菌毒力基因分析利用云南分离株Avr-pii、Avr-pia、Avr-Hattan3 3个毒力基因进行杂交研究。这些无毒基因被定位到真菌的遗传图谱上。沿Avr-Hattan 3构建了一个长度为600kb的BAC结构。另一方面，从日本分离物与罕见的雌雄同体分离物Guy11杂交中也鉴定出Avr-pia。利用宿主特异性突变体，分离出与Avr-pia基因座紧密相连的DNA片段PM-01。其中一个含有PM-01片段的cosmid克隆能够补充宿主特异性突变，表明该克隆含有Avr-pia基因。(2)灰稻瘟病菌重组修复基因分析从灰稻瘟病菌基因组中克隆出RAD52、RAD54和MRE11同源基因，分别命名为Rhm52、Rhm54和Mhm11。在这些同源物中，Rhm54被发现与稻瘟菌mus23突变体的表型互补，并在稻瘟病菌细胞中被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.