A Colletotrichum gloeosporioides cerato-platanin protein, CgCP1, contributes to conidiation and plays roles in the interaction with rubber tree.

Abstract

Colletotrichum gloeosporioides is the causal agent of rubber tree anthracnose and leads to serious losses of natural rubber production. The pathogenesis of C. gloeosporioides on rubber tree remains unknown. Cerato-platanin proteins are small, secreted cysteine-rich proteins that contribute to virulence and function in plant-fungal interactions. A gene encoding cerato-platanin protein, CgCP1, was identified in C. gloeosporioides. In silico analysis indicated that CgCP1 belongs to a new branch of the cerato-platanin protein family. The CgCP1 knockout mutants (ΔCgCP1) and complementary strain (Res-ΔCgCP1) were generated to investigate its biological function. The results showed that the speed of growth of aerial hyphae was not significantly different among the wild-type (WT), ΔCgCP1, and Res-ΔCgCP1 strains, but conidiation of ΔCgCP1 significantly decreased in comparison with the WT. The pathogenicity test proved that the severity of symptoms caused by ΔCgCP1 was reduced significantly compared with those caused by the Res-ΔCgCP1 and WT strains. Additionally, CgCP1 induced necrosis-like cell death on tobacco leaf and accumulation of reactive oxygen species in rubber tree mesophyll protoplasts. Altogether, these data indicate the involvement of C. gloeosporioides CgCP1 in conidiation and the interaction with rubber tree.