GlPP2C1 Silencing Increases the Content of Ganoderma lingzhi Polysaccharide (GL-PS) and Enhances Slt2 Phosphorylation

Polysaccharides have attracted much attention in the food industry due to their diverse biological activities. To date, research on the mechanism of polysaccharide synthesis has mainly focused on the role of crucial enzymes in the polysaccharide synthesis pathway, but other genes that regulate polysaccharide synthesis have not been well explored. In this study, the GlPP2C1 gene, encoding a phosphoprotein type 2C phosphatase, was cloned, and PP2C-silenced strains (PP2C1i-1 and PP2C1i-3) were screened. Measurements of the polysaccharide content and cell wall tolerance revealed that GlPP2C1 silencing increased the polysaccharide content and enhanced cell wall resistance in Ganoderma lingzhi. The contents of intracellular polysaccharides (IPS), extracellular polysaccharides (EPS) and β-1,3-D-glucan in PP2C-silenced strains were increased by 25%, 33% and 36%, respectively, compared with those in the WT strains and strains transformed with an empty vector. Further mechanistic studies showed that GlPP2C1 silencing increased the content of Ganoderma lingzhi polysaccharides (GL-PS) through Slt2. In summary, this study revealed the mechanism through which protein phosphatase regulates GL-PS biosynthesis for the first time.