Phylogeny of Regulators of G-Protein Signaling Genes in Leptographium qinlingensis and Expression Levels of Three RGSs in Response to Different Terpenoids

Leptographium qinlingensisis a bark beetle-vectored pine pathogen in the Chinese white pine beetle (Dendroctonus armandi) epidemic in Northwest China.L. qinlingensiscolonizes pines despite the trees’ massive oleoresin terpenoid defenses. Regulators of G-protein signaling (RGS) proteins modulate heterotrimeric G-protein signaling negatively and play multiple roles in the growth, asexual development, and pathogenicity of fungi. In this study, we have identified threeL. qinlingensis RGSgenes, and the phylogenetic analysis shows the highest homology with the regulators of G-protein signaling proteins sequence fromOphiostoma piceaeandGrosmannia clavigera. The expression profiles of three RGSs in the mycelium ofL. qinlingensistreated with six different terpenoids were detected, as well as their growth rates. Under six terpenoid treatments, the growth and reproduction inL. qinlingensiswere significantly inhibited, and the growth inflection day was delayed from 8 days to 12–13 days. By analyzing the expression level of threeRGSgenes ofL. qinlingensiswith different treatments, results indicate thatLqFlbAplays a crucial role in controlling fungal growth, and bothLqRax1andLqRgsAare involved in overcoming the host chemical resistances and successful colonization.Keywords:Leptographiumqinlingensis;regulators of G-protein signaling;terpene tolerance;host resistances;expression