Overexpression of the phosphatase gene Ssppe1 regulates the sexual mating and pathogenicity of Sporisorium scitamineum

Sugarcane supplies approximately 80 % of global sugar. Sugarcane smut, caused by Sporisorium scitamineum, is one of the major fungal diseases that significantly reduces sugarcane production and quality. Current field management strategies deliver limited protection against this disease. Elucidating the molecular mechanisms underlying S. scitamineum infection will support the development of new measures for the prevention and control of sugarcane smut.

Reversible protein phosphorylation governs multiple biological processes in plant‑pathogenic fungi. While protein kinases have been well‑studied in S. scitamineum, information about protein phosphatases and their regulatory role remains poorly characterized. A research team from Guangxi University generated Ssppe1 overexpression mutants (OE‑Ssppe1) via Agrobacterium‑mediated transformation and systematically characterized mutant phenotypes, as reported in Acta Microbiologica Sinica.

 

Previous research by this team has shown that deleting the Ssppe1 gene, which encodes a PP2A-like phosphatase, impairs sexual mating and pathogenicity. In the present study, they found that overexpression of the Ssppe1 gene also lead to severe physiological defects. Overexpressing Ssppe1 produced pseudohypha‑like sporidia with multiple nuclei and abnormal chitin deposition. OE-Ssppe1 mutants exhibited significantly increased sensitivity to osmotic stress and cell wall integrity stress induced by NaCl and SDS compared to the WT strains. Overexpression of the Ssppe1 gene also leads to defects in sexual mating and pathogenicity.

RNA-Seq analysis illustrated that Differentially expressed genes were significantly enriched in pathways for protein folding and chaperone function. In addition, multiple heat‑shock protein genes were significantly up-regulated. These results suggest that SsPpe1 is a potential target for screening antifungal agents.

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