Isolation of Gene Mutation from a Pathogenicity-Enhanced Mutant of Magnaporthe oryzae

Abstract

To find new genes involved in fungal pathogenicity, a mutant (B11) exhibiting enhanced pathogenicity was isolated from an Agrobacterium-mediated transformed Magnaporthe oryzae mutant library. Southern blotting analysis showed that T-DNA insertion in the B11 genome was a single copy. TAIL-PCR and sequence alignment analyses revealed that a putative gene locus MG01679 was interrupted by the T-DNA fragment. By using the PCR-based method, the DNA and cDNA of the mutant gene MG01679 was cloned and sequenced. The open reading frame of MG01679 includes one intron and two exons, and the coding sequence is 696 bp in length and encodes a 231 amino acid peptide. Protein similarity analysis indicated that the gene belongs to the ThiJ/Pfp I protein family, and the gene was thus designated MgThiJ1. MgThiJ1 showed 57% similarity to FOXG_09029 from Fusarium oxysporum and 54% similarity to FGSG_08979 from F. graminearum in protein sequence. MgThiJ1 gene might act as a negative regulator in vegetative growth and pathogenesis in filamentous fungi, and its specific mechanism needs to be studied further.