Mitogen-Activated Protein Kinases SvPmk1 and SvMps1 Are Critical for Abiotic Stress Resistance, Development and Pathogenesis of Sclerotiophoma versabilis

Mitogen-activated protein kinase (MAPK) signaling pathways are evolutionarily conserved in eukaryotes and modulate responses to both internal and external stimuli. Pmk1 and Mps MAPK pathways regulate stress tolerance, vegetative growth and cell wall integrity in Saccharomyces cerevisiae and Pyricularia oryzae. Here, we deployed genetic and cell biology strategies to investigate the roles of the orthologs of Pmk1 and Mps1 in Sclerotiophoma versabilis (herein referred to as SvPmk1 and SvMps1, respectively). Our results showed that SvPmk1 and SvMps1 are involved in hyphal development, asexual reproduction and pathogenesis in S. versabilis. We found that increment Svpmk1 and increment Svmps1 mutants have significantly reduced vegetative growths on PDA supplemented with osmotic stress-inducing agents, compared to the wild type, with increment Svpmps1 being hypersensitive to hydrogen peroxide. The two mutants failed to produce pycnidia and have reduced pathogenicity on Pseudostellaria heterophylla. Unlike SvPmk1, SvMps1 was found to be indispensable for the fungal cell wall integrity. Confocal microscopic analyses revealed that SvPmk1 and SvMps1 are ubiquitously expressed in the cytosol and nucleus. Taken together, we demonstrate here that SvPmk1 and SvMps1 play critical roles in the stress resistance, development and pathogenesis of S. versabilis.

Automated summary

In this study, the roles of Pmk1 and Mps1 in Sclerotiophoma versabilis were investigated using genetic and cell biology strategies. The results showed that SvPmk1 and SvMps1 are involved in hyphal development, asexual reproduction, and pathogenesis. The mutants exhibited reduced growth under osmotic stress and hypersensitivity to hydrogen peroxide. This study demonstrates the critical roles of SvPmk1 and SvMps1 in stress resistance, development, and pathogenicity of S. versabilis.