FvVam6 is associated with fungal development and fumonisin biosynthesis via vacuole morphology regulation in Fusarium verticillioides

As the largest multifunctional and dynamic organelle in fungi, vacuoles are associated with different organelles through membrane contact sites and participate in various cellular processes. Vacuole and mitochondria patch (vCLAMP), the membrane contact site that tethers vacuoles and mitochondria, is indispensable for reciprocal interplay between these two organelles. The impairment of vacuoles and mitochondria significantly suppressed FB₁ production in Fusarium verticillioides. However, the understanding of how vCLAMP complex regulates fumonisin biosynthesis remained unknown. Herein, the biological functions of vCLAMP component Vam6 were investigated in F. verticillioides. Our results showed that FvVam6 deletion mutant ΔFvVam6 exhibited palpable defects in fungal development, stresses responses and pathogenicity. In addition, abnormal vacuolar morphology and significantly reduced FB₁ production were observed in ΔFvVam6. Furthermore, we demonstrated that two vacuolar sorting protein 39 (Vps39) domains and clathrin domain were critical for the biological functions of FvVam6, while clathrin and Vps39-2 domains played dominant roles in the regulation of virulence and FB₁ production. Taken together, our results advanced our understanding of vCLAMP in fumonisin biosynthesis in plant pathogenic fungus F. verticillioides.