The CgDbf2/CgMob1-CgCdc14 Phosphorylation Module Mediated Phosphatase Activity Regulates MEN Signalling and Pathogenicity in Colletotrichum gloeosporioides.

Abstract

The mitotic exit network (MEN) plays pivotal roles in regulating cell morphology and pathogenicity in eukaryotic organisms. However, the precise mechanisms underlying how the MEN signalling pathway integrates and coordinates morphologiensis, host derived ROS homoeostasis and virulence remains poorly understood in phytopathogenic fungi. In this study, combined with RNA-seq, biochemical and genetic analyses, we found that CgDbf2 and CgMob1 form a protein complex in Colletotrichum gloeosporioides. As an essential component of MEN signalling pathway, CgDbf2/CgMob1 complex is critical for maintaining cell wall integrity (CWI), and enabling resistance to the fungicide carbendazim. Disruption of CgDBF2 and CgMOB1 results in significantly reduced virulence, primarily due to impaired appressorium formation and diminished invasive growth capabilities. Additionally, our findings reveal that CgDbf2 interacts with and phosphorylates the phosphatase CgCdc14. The residues Ser427 and Thr428 of CgCdc14 are critical sites phosphorylated by CgDbf2, enhancing CgCdc14 phosphatase activity and contributing to fungal virulence. Moreover, our findings highlight that the Dbf2/Mob1-Cdc14 axis coordinates CWI and responses to reactive oxygen species, both of which are crucial for plant infection. Our data underscore that the phosphatase activity of CgCdc14, which is dependent on phosphorylation by CgDbf2, is essential for crosstalk between MEN and CWI. These findings offer novel insights into the molecular mechanisms governing plant infection of phytopathogenic fungi and provide potential targets for developing antifungal strategies.