稻瘟病菌致病性增强突变体B11的基因分析

Analysis on Gene Locus of Magnaporthe oryzae B11,a Pathogenicity-Enhanced Mutant

在农杆菌介导转化(AtMT)的稻瘟病菌突变体库中,筛选到一个菌丝生长增快,对大麦致病性增强的突变体B11。Southern杂交分析表明B11中T-DNA为单拷贝插入。通过TAIL-PCR克隆插入位点侧翼序列,序列测定与比对分析显示T-DNA位于假想基因MG01679的编码区内。利用PCR的方法,克隆基因的DNA和cDNA序列。该基因开放阅读框包括1个内含子和2个外显子,编码序列的长度为696 bp,编码231个氨基酸的多肽,编码产物属于ThiJ/PfpⅠ蛋白家族。因此,将该基因命名为MgThiJ1。MgThiJ1蛋白序列与尖胞镰刀菌假想蛋白FOXG_09029有57%的同源性,与禾谷镰刀菌假想蛋白FGSG_08979有54%的同源性。MgThiJ1基因可能为致病过程的负调控因子,其具体作用机制有待进一步研究。

A Magnaporthe oryzae mutant Bll was obtained by Agrobacterium-mediated transformation （AtMT） method, which enhanced the pathogenicity to barley. Southern blotting analysis indicated that T-DNA insert in the Bll genome was single copy. TAIL-PCR and sequence alignment analysis indicated that the T-DNA insertion broke the putative gene locus MG01679. By using PCR-based method, the DNA and cDNA of the gene locus were cloned and sequenced. The open reading frame of the gene includes one intron and two exons. And the coding sequence is 696 bp long and encodes a 231 amino acid peptide. Protein similarity analysis indicated that the product of the gene belongs to the ThiJ/Pfp I protein family, and the gene was thus assigned MgThiJ1. MgThiJ1 shows 57~ similarity to FOXG_09029 from Fusarium oxysporum, and 540/00 similarity to FGSG_08979 from Fusarium graminearum in protein sequence. MgThiJ1 gene may be a negative regulator to vegetative growth and pathogenicity in filamentous fungi, and its specific mechanism need to be studied further.