Abstract

Colletotrichum gloeosporioides, an important phytopathogenic fungus, mainly infects tropical fruits and results in serious anthracnose. Previous studies have shown that melanin biosynthesis inhibitor can inhibit the melanization of the appressoria ofMagnaporthe griseaandColletotrichumorbiculare, resulting in limited infection of the hosts. In this study, we identified and characterized a scytalone dehydratase gene (CgSCD1) fromC. gloeosporioideswhich is involved in melanin synthesis. TheCgSCD1gene deletion mutantΔCgscd1was obtained using homologous recombination. TheΔCgscd1mutant showed no melanin accumulation on appressoria formation and vegetative hyphae. Furthermore, the virulence ofΔCgscd1was significantly reduced in comparison with the wild-type (WT) strain. Further investigations showed that the growth rate as well as germination and appressorium formation ofΔCgscd1displayed no difference compared to the wild-type and complemented transformant Cgscd1comstrains. Furthermore, we found that the appressorial turgor pressure in theΔCgscd1mutant showed no difference compared to that in the WT and Cgscd1comstrains in the incipient cytorrhysis experiment. However, fewer infectious hyphae ofΔCgscd1were observed in the penetration experiments, suggesting that the penetration ability of nonpigmented appressoria was partially impaired. In conclusion, we identified theCgSCD1gene, which is involved in melanin synthesis and pathogenicity, and found that the melanization defect did not affect appressorial turgor pressure inC. gloeosporioides.Keywords:Colletotrichum gloeosporioides;scytalone dehydratase;appressoria;virulence