The MAP Kinase SsKpp2 Is Required for Mating/Filamentation in Sporisorium scitamineum

In the phytopathogenic fungus , sexual mating between two compatible haploid cells and the subsequent formation of dikaryotic hyphae is essential for infection. This process was shown to be commonly regulated by a mitogen-activated protein kinase (MAPK) and a cAMP/PKA signaling pathway in the corn smut fungus but remains largely unknown in . In this study, we identified a conserved putative MAP kinase Kpp2 in and named it as SsKpp2. The Δ mutant displayed significant reduction in mating/filamentation, which could be partially restored by addition of cAMP or tryptophol, a quorum-sensing molecule identified in budding yeast. Transcriptional profiling showed that genes governing mating or tryptophol biosynthesis were significantly differentially regulated in the Δ mutant compared to the WT, under mating condition. Our results demonstrate that the MAP kinase SsKpp2 is required for mating/filamentation likely through regulating the conserved pheromone signal transduction pathway and tryptophol production.