Abstract: thga3 gene encoding a type Ⅲ G protein α subunit Thga3 in Trichoderma harzianum Th-33 may participated in the regulation of growth, spore production, mycoparasitism, hydrophobic and chitinase activity. In order to clarify its function, Illumina RNA-seq technology (RNA-seq) was used to analyze the differentially expressed genes (DEGs) between the wild-type strain Th-33 and thga3 knockout mutant △thga3, and the expression of genes related to the G protein signaling pathways, cell wall degradation enzymes, and the spore production were analysed. Comparing to wild Th-33, three DEGs of G protein receptor proteins, three chitinase genes, one sporulation regulatory gene brlA encoding a nucleic acid binding protein and one hydrophobin gene Tha_09745 were down-regulated, and one G protein signal transduction protein gene coding RGS1 was up-regulated in △thga3. It was hypothesized that thga3 may regulate sporulation by regulating the expression of brlA, regulate the mycelial hydrophobicity by regulating the expression of Tha_09745, and regulate the chitinase activity and affect the expression of other proteins in the G protein signaling network, which may affect the antagonism and mycoparasitism, as well as other biological characteristics. This study lays a foundation for further exploration on the regulation of G protein signaling pathway in Trichoderma biocontrol characteristics and its mechanism.

Key words: Trichoderma harzianum, transcriptome sequencing, differentially expressed genes, Thga3