Genome-wide identification of small GTPase gene family members in Lentinula edodes and the roles of LeRho1 in biotic and abiotic stress responses

Lentinula edodes (L. edodes) is the largest proportion of edible mushrooms in China. However, the yield is highly susceptible to environmental stress. Factors such as high-temperature stress, low-temperature stress, Trichoderma infection, heavy metal stress, and light exposure all impact the growth status of L. edodes mycelium to varying degrees. Small GTPase is a small molecular switch involved in multiple biological processes of eukaryotes. The main functions of small GTPase in fungi include morphogenesis, secondary metabolism, vesicle trafficking, stress response, and virulence. However, the understanding of small GTPase in L. edodes is minimal. In this study, a total of 34 small GTPase genes in L. edodes were identified and clustered into five subfamilies, namely, Rho, Ras, Arf, Rab, and Ran. The 34 identified genes were phylogenetically analyzed and compared with those of various ascomycetes and basidiomycetes using the genome assembly and annotation databases of L. edodes. The results of expression patterns of 34 small GTPase genes under different biotic and abiotic stresses showed that most of these genes exhibited different degrees of responses to different stresses. The gene function analysis showed that the heat tolerance, resistance to Trichoderma atroviride (T. atroviride) infection, and light sensitivity of the LeRho1 overexpression transformants were significantly higher than those of the control transformants. This study verified that LeRho1 is an important stress-resistant gene in L. edodes and that this gene is distributed in edible fungi. This study verified that LeRho1 is an important stress-resistant gene in L. edodes and that this gene is distributed in edible fungi. Our findings provide a theoretical basis for further research on the stress response mechanism of the small GTPases in large edible fungi.IMPORTANCEThis study verified that LeRho1 is an important stress-resistant gene in L. edodes and that this gene is distributed in edible fungi. Clarifying the function of LeRho1 protein in the heat stress response of L. edodes, and analyzing the differentiation of the structure and function of small GTPase in fungi such as L. edodes, Saccharomyces cerevisiae, and Aspergillus fumigatus, is of great significance for elucidating the heat stress response mechanism of filamentous fungi of Agariales under heat stress and for conducting germplasm innovation for heat-tolerant edible fungi.