Temporally Programmed Virulence Cascade Drives Progressive Maize Root Rot by Fusarium graminearum

Fusarium graminearum threatens grain safety through trichothecene mycotoxins, yet how it temporally orchestrates virulence during early root colonization-which compromises seedling vigor and facilitates stem invasion-remains unclear. We performed high-resolution transcriptomics of F. graminearum infecting maize roots every 6 h over 48 hpi, revealing three infection phases: Penetration Initiation (0-6 hpi), Colonization Establishment (12 hpi), and Systemic Disruption (18-48 hpi). Among 6,839 fungal genes, we delineated a three-phase virulence program: rapid activation of protein synthesis enables early secretion of effectors and hydrolases that facilitate host attachment and penetration; sustained deployment of diverse hydrolases and immunosuppressive effectors enables colonization through combined nutrient acquisition and defense suppression; and late-phase vascular degradation coupled with deoxynivalenol (DON) biosynthesis may contribute to systemic host disruption by compromising tissue integrity and disarming immunity. This program coincides with a shift from ROS scavenging to endogenous signaling that may promote toxin production and invasive growth. Notably, we identified FgCPA1, a conserved Phase II carboxypeptidase A essential for root colonization, whose protease domain triggers light-independent cell death in N. benthamiana independent of its signal peptide. This temporal framework uncovers phase-specific coordination of tissue invasion and mycotoxin production, providing actionable targets for anti-virulence strategies to safeguard grain quality.