MaFKS, a β-1,3-glucan synthase, is involved in cell wall integrity, hyperosmotic pressure tolerance and conidiation in Metarhizium acridum

beta-Glucan is an essential cell wall structural component in most fungi and its helical structure is important for maintenance of cell wall elasticity in fungi. The gene encoding beta-1,3-glucan synthase in the entomopathogenic fungus Metarhizium acridum (MaFKS; HQ441252) was cloned. The function of MaFKS was analyzed by RNA interference (RNAi). FKS-RNAi transformants were more sensitive to agents that disturb the cell wall or cell membrane and to hyperosmotic stress than the wild type. In comparison with the wild type, aerial hyphae and conidial yield were obviously reduced in FKS-RNAi transformants on potato dextrose agar plates with Congo red, calcofluor white, sodium dodecyl sulfate, KCl, sorbitol or mannitol. The beta-1,3-glucan content significantly decreased in FKS-RNAi transformants, indicating that MaFKS affects the synthesis of beta-1,3-glucan in the fungal cell wall and confirming its role in the maintenance of cell wall integrity, hyperosmotic pressure tolerance and conidiation.