Citin synthase gene FgCHS8 affects virulence and fungal cell wall sensitivity to environmental stress in Fusarium graminearum
a Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
b Agronomy College, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
c Agricultural Science Research Institute, Xichang, Sichuan 615000, China
1 Contributed equally to this paper.
•FgCHS8 have chitin synthase activity and regulates the accumulation of chitin.
•FgCHS8 does not affect spore production.
•FgCHS8 is strongly expressed in the septa zone.
•FgCHS8 is important for cell wall sensitivity to environmental stress factors, pathogenicity, and deoxynivalenol production.
•The mutant phenotypes were restored by the wild type FgCHS8 gene.
Fusarium graminearum is the major causal agent of Fusarium head blight (FHB) of wheat and barley and is considered to be one of the most devastating plant diseases worldwide. Chitin is a critical component of the fungal cell wall and is polymerized from UDP-N-acetyl-alpha-d-glucosamine by chitin synthase, an integral membrane enzyme. We characterized FgCHS8, a new class of the chitin synthase gene in F. graminearum. Disruption of FgCHS8 by Agrobacterium tumefaciens-mediated transformation resulted in reduced accumulation of chitin, decreased chitin synthase activity, and had no effect on conidia growth when compared with the wild-type isolate. The ΔFgCHS8 mutant strain had a growth rate comparable to that of the wild-type isolate in vitro. However, ΔFgCHS8 had reduced growth when grown on agar supplemented with either 0.025 % SDS or 0.9 mM salicylic acid. ΔFgCHS8 produced significantly less deoxynivalenol and exhibited reduced pathogenicity in wheat spikes. Re-introduction of a functional FgCHS8 gene into the ΔFgCHS8 mutant strain restored the wild-type phenotypes. Fluorescence microscopy revealed that FgCHS8 protein was initially expressed in the septa zone, and then gradually distributed over the entire cellular membrane, indicating that FgCHS8 was required for cell wall development. Our results demonstrated that FgCHS8 is important for cell wall sensitivity to environmental stress factors and deoxynivalenol production in F. graminearum.
Chitin; Fusarium head blight; Mycotoxin; Pathogenicity; Wheat
Fungal Biology, Available online 16 February 2016