Pathogenicity-related Gene Cloning And Functional Study From T-DNA Insertional Mutant Focr4-1453of Fusarium Oxysporum F.sp. Cubense Race4

Banana is a kind of common tropical fruit. It has a strategic position on import and export trade in the world, which plays a huge boost to economic development of hot zone.Banana was planted all over the world and it has many kinds of plant disease. Banana fusarium-wilt disease also called Panama disease is one of the most important lethal disease. It was caused by Fusarium oxysporum f.sp. cubense and this plant disease is threatening all the Banana industry. Fusarium oxysporum f.sp. cubense has four races, and the race4is significantly different from other three races, it has the widest host range and the strongest pathogenicity. Currently, banana wilt disease pathogenesis is unclear. In order to control banana wilt disease, we need to find out pathogenicity-related genes for developing new drugs. Pathogen and host interactions are determined by the pathogenicity-related genes. In this study, we will mainly focus on the mutanted gene’s impacts on its host’s pathogenicity.Here in the laboratory we have T-DNA insertional mutant library of Fusarium oxysporum f.sp. cubense race4. Strain Focr4-1453we screened by pathogenicity test. The flanking sequence of mutantional site was obtained with DW-ACT-PCR technology. We analysed the flanking sequences on NCBI via Blast N analysis and got a contig of genome sequence of Focr4. Primers were designed to clone full-length cDNA of the mutant gene based on the ORF prediction. The full cDNA of pathogenicity-related gene of mutant strain Focr4-1453was cloned by RACE technology. The same gene was deleted from wild-type strain and get a mutant named△Focr4-1453. Later, we complemented the gene back on△Focr4-1453, and get a mutant named△Focr4-1453-cp-1. The mutant strains’ pathogenicity was decreased very seriously. Wild-type strain can make banana leaves yellow and cause plants wilting. But not the mutant strains. The biological phenotype research showed that, mutant strains have quite different characteristics. Compared to wild type strain, the mutants have smaller clony size with clolr fades. Mycelium became exquisite and white. Spore germination rates decreased, while germination time became longer. This gene could not be translated into protein after transcription in the normal way, because it didn’t express when it was fused with GFP(Gree florencent protein).Further investigation on this gene is in progress.