Cytochrome c-peroxidase modulates ROS homeostasis to regulate the sexual mating of Sporisorium scitamineum.

Abstract

Sugarcane smut, caused by the basidiomycetous fungus Sporisorium scitamineum, is a global fungal disease resulting in substantial economic losses. Our previous research has highlighted the significant role of reactive oxide species (ROS) in the sexual reproduction of S. scitamineum, yet the underlying mechanisms remain unclear. In this study, we identified the cytochrome c-peroxidase encoding gene, SsCCP1, as crucial for oxidative stress resistance. We further found that absence of SsCcp1 leads to defects in mating/filamentation and disrupts intracellular ROS homeostasis. However, restoration of mating/filamentation of SsCCP1 deletion mutants was partially achieved with exogenous antioxidants (vitamin C or vitamin E). Notably, transcription of the pheromone response factor SsPRF1, pivotal for mating/filamentation of S. scitamineum, is significantly reduced in the SsCCP1 deletion mutants or under exogenous hydrogen peroxide (H2O2) conditions. Nevertheless, the addition of exogenous vitamin C for 60 min significantly up-regulated the SsPRF1 gene in the SsCCP1 deletion mutants. Moreover, the constitutive expression of SsPRF1 essentially reinstated the mating/filamentation of SsCCP1 deletion mutants, suggesting that SsCcp1 mediates the transcriptional activity of SsPRF1 by maintaining ROS homeostasis to regulate the mating/filamentation of S. scitamineum. Further investigations revealed that SsCcp1 is necessary for ROS detoxification and full pathogenicity in planta. Overall, this study not only unveils the importance of SsCcp1 in S. scitamineum mating/filamentation, ROS detoxification, and virulence but also provides insights into the role of SsCcp1-regulated ROS homeostasis in sexual reproduction of S. scitamineum. IMPORTANCE Reactive oxygen species play an important role in pathogen-plant interactions. In fungi, cytochrome c-peroxidase maintains intracellular ROS homeostasis by utilizing H2O2 as an electron acceptor to oxidize ferrocytochrome c, thereby contributing to disease pathogenesis. In this study, our investigation reveals that the cytochrome c-peroxidase encoding gene, SsCCP1, not only plays a key role in resisting H2O2 toxicity but is also essential for the mating/filamentation and pathogenicity of S. scitamineum. We further uncover that SsCcp1 mediates the expression of SsPrf1 by maintaining intracellular ROS homeostasis to regulate S. scitamineum mating/filamentation. Our findings provide novel insights into how cytochrome c-peroxidase regulates sexual reproduction in phytopathogenic fungi, presenting a theoretical foundation for designing new disease control strategies.