The tetraspanin gene MaPls1 contributes to virulence by affecting germination, appressorial function and enzymes for cuticle-degradation in the entomopathogenic fungus, Metarhizium acridium

• 1、Chongqing Engineering Research Center for Fungal Insecticides and Key Lab of Functional Gene and Regulation Technology Under Chongqing Municipal Education Commission, School of Life Sciences, Chongqing University, Chongqing 400030.

Abstract：Tetraspanins regulate cellular activities through association with other components on membrane in most eukaryote. The tetraspanin Pls1 controls an appressorial-mediated penetration in phytopathogenic fungi. However, the mode of regulation and signal pathways that Pls1 involved in are not clear. In this study, a Pls1 gene (MaPls1) was functionally characterized in the entomopathogenic fungus Metarhizium acridum. MaPls1 was highly expressed in mycelium and appressorium, and accumulated on the plasma membrane or inside the cytoplasm. The ΔMaPls1 had a delayed germination and appressorium formation and impaired turgor pressure on locust wing, but a normal vegetative growth and conidiation on medium. Bioassays showed that ΔMaPls1 had a decreased virulence and hyphal body formation in hemolymph when conidia were topically inoculated, but had no difference from wild type when the insect cuticle was bypassed. Moreover, the ability of breaching the cuticle from insect inside was impaired. Digital Gene Expression analysis between the ΔMaPls1 and wild type revealed that genes involved in hydrolyzing host cuticle and cell wall synthesis and remodeling were dramatically down-regulated. MaPls1 participated in a wide crosstalk with other signal pathways, including calmodulin-dependent pathway, and GTPase and cAMP-PKA etc. Taken together, these results demonstrated the important roles of MaPls1 at the early stage of infection-associated development in M. acridum.

keywords： Tetraspanin Pls1 penetration pathogenicity entomopathogenic fungus.

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