The G-protein alpha subunit CgGa1 mediates growth, sporulation, penetration and pathogenicity in Colletotrichum gloeosporioides

Colletotrichum gloeosporioides is the main pathogen causing rubber anthracnose, which brings huge economic loss to the natural rubber industry. Heterotrimeric G proteins play a vital role in signal transduction in filamentous fungi, and G alpha subunits are the major component of G proteins. In this study, we characterize a group I G alpha subunit CgGa1 in C. gloeosporioides as a homolog of MagB in Pyricularia oryzae. CgGa1 encodes a 353-amino acid protein and has a G_alpha domain. Deletion of CgGa1 results in reduced vegetative growth and conidia yield, and the mutant cannot produce a fruiting body. The CgGa1 deletion mutant also exhibits decreased conidial germination and appressorium formation significantly. Moreover, the mutant has an obvious deficiency in penetration and loses its virulence completely. Transcriptome analysis showed that CgGa1 could affect the expression of many genes related to carbohydrate metabolism, amino acid metabolism and signal transduction, etc. In conclusion, CgGa1 regulates growth, asexual and sexual sporulation, appressorium formation, penetration and pathogenicity of C. gloeosporioides.