Characterization and Genome Analysis of Fusarium oxysporum Provides Insights into the Pathogenic Mechanisms of the Pokkah Boeng Disease in China.

Pokkah Boeng Disease (PBD) is a severe and devastating disease that causes significant damage and yield losses in China. The pathogenic fungus Fusarium oxysporum is responsible for the rapid onset of top rot symptoms in sugarcane. In this study, we selected a representative strain, BS2-6, to perform morphological observations of colonies and determine pathogenicity. We examined the effects of BS2-6 infestation on the ultrastructure of sugarcane leaves. Moreover, we sequenced the whole genome of BS2-6 and examined the effects of various nitrogen sources and chemical reagents on its growth and pathogenicity. Our results indicate that sugarcane leaves inoculated with BS2-6 quickly succumb to heart leaf and growing rot. Ultrastructural analysis revealed that the surface tissues of the diseased leaves were destroyed with mycelium, and conidia blocked leaf stomata, which ultimately led to the degradation of leaf tissues. Ammoniacal nitrogen significantly promoted mycelial growth, pigment secretion, and the expression of genes related to secondary metabolite synthesis, thereby accelerating the development of PBD. In addition, we found that carbendazim effectively inhibited the growth of BS2-6 at various concentrations. These findings provide important insights for the effective prevention and control of PBD during sugarcane production.