Phenotype analysis of the T-DNA insertion mutant Focr4-1562 of Fusarium oxysporum f. sp. cubense race 4 and its gene-knockout mutant
尖镰孢古巴专化型4号小种T-DNA插入突变体Focr4-1562及其基因敲除子的生物学表型研究

Fusarium oxysporum f.sp.cubense race 4(Focr4) is considered as one of the most destructive pathogens of the world distributed soil-borne banana.Its pathogenesis has not been clearly understood.The pathogenicity of mutant Focr4-1562 was significantly weakened after T-DNA insertion in its gene sequence.The inserted exogenous gene caused changes in functions of some genes in the △Focr4-1562.By means of cellophane penetration test as well as pathogenic test by inoculating live leaves and roots,changes in pathogenic phenotype of the mutant Focr4-1562 and △Focr4-1562 were compared with the wild type Focr4.The mutant Focr4-1562 and △Focr4-1562 could not grow through cellophane,and didn’t cause any disease spots and brown coloration in corm vascular bundle.The results showed that the optimum growth temperature of the wild type Focr4,Focr4-1562 and △Focr4-1562 were all at 28℃,and their optimum growth pH was 7.0 to 8.0.No evident difference was found in their spore morphology,but the sporulation of △Focr4-1562 was obviously delayed,and its sporulation capacity was significantly decreased.The Focr4-1562 and △Focr4-1562 were more resistant to cell wall degrading enzyme than the wild type Focr4-193-6.It is concluded that the knockout of the pathogenic gene is responsible for conidial production and cell wall formation of the wild type Focr4-193-6.