Roles of Three Genes in the Development and Pathogenicity Regulation of .

Fusarium head blight (FHB) is a devastating fungal disease caused by . Pectin lyase, a pectinase, acts on the α-1,4-glycosidic linkage of galacturonic acid primarily by β-elimination. In this study, three pectin lyase genes (, , ) in were selected, and deletion mutants (Δ, , ) were constructed by homologous recombination for functional characterization. The gene deletions affected the morphology and growth rate of on pectin medium at various concentrations, with the growth rate of Δ being more significant. The growth of Δ colonies slowed at pH 4, with optimal growth at pH 6.5, whereas Δ and Δ exhibited greater inhibition at pH 8. Colony morphology and diameter of the deletion mutants showed no significant differences compared to the wild-type strain PH-1, and there was no effect on conidial production or germination rate. Pathogenicity assays demonstrated that gene deletion significantly reduced the ability of to infest corn silks and wheat ears, and that Δ showed a more pronounced reduction in pathogenicity on wheat spikes. In summary, the pectin lyase genes (, , ) are involved in pectin utilization and are influenced by external pH conditions, which attenuate the pathogenicity of without affecting its vegetative growth or asexual spore formation. These findings elucidate the roles of these genes and provide a basis for controlling FHB.