The Colletotrichum gloeosporioides perilipin homologue CAP 20 regulates functional appressorial formation and fungal virulence

Previous studies of the CAP20 gene in Colletotrichum gloeosporioides show that the CAP20 gene may affect virulence in avocados and tomatoes. In this study, we characterized the function of CAP20 from C.gloeosporioides, the causal agent of Colletotrichum leaf fall disease of Hevea brasilience. CAP20 encodes a perilipin homologue protein. Further investigations showed that the Cap20-GFP fusion protein localized in lipid droplets in hypha and conidia. A C.gloeosporioides mutant, lacking CAP20, had thinner spores and smaller appressoria, and its turgor pressure generation was dramatically reduced and pore size was enlarged. Furthermore, we tested the pathogenicity of conidia from the wild type, gene-deleted mutant and complemented transformant C.gloeosporioides on the leaves of rubber trees in sterile water and 0.19M PEG2000. Conidia from the wild type and complemented transformant C.gloeosporioides in 0.19M PEG2000 caused necrotic lesions and did not produce any lesion with the CAP20 null mutant. But all of them had developed normal disease lesions when they were inoculated in water. These results suggest that CAP20 is a perilipin homologue protein and is involved in functional appressoria development in C.gloeosporioides. CAP20 gene only affects fungal virulence to some extent by reducing the penetration of the immature appressoria into host cuticle in C.gloeosporioides.