A Network of Sporogenesis-Responsive Genes Regulates the Growth, Asexual Sporogenesis, Pathogenesis and Fusaric Acid Production of f. sp. .

The conidia produced by f. sp. (Foc), the causative agent of Fusarium Wilt of Banana (FWB), play central roles in the disease cycle, as the pathogen lacks a sexual reproduction process. Until now, the molecular regulation network of asexual sporogenesis has not been clearly understood in Foc. Herein, we identified and functionally characterized thirteen (13) putative sporulation-responsive genes in Foc, namely , , , , , , , , , , , and . We demonstrated that , , , , , , and mediate conidiophore formation, whereas and are important for phialide formation and conidiophore formation. The expression level of was significantly decreased in the Δ mutant, and yeast one-hybrid and ChIP-qPCR analyses further confirmed that FocMedA(a) could bind to the promoter of during micro- and macroconidiation. Moreover, the transcript abundance of the gene was significantly reduced in the Δ mutant, and it not only was found to function as an activator of micro- and macroconidium formation but also served as a repressor of chlamydospore production. In addition, the deletions of , , and resulted in increased chlamydosporulation, whereas and gene deletions reduced chlamydosporulation. Furthermore, , , and were found to be important regulators for pathogenicity and fusaric acid synthesis in Foc. The present study therefore advances our understanding of the regulation pathways of the asexual development and functional interdependence of sporulation-responsive genes in Foc.