Identification and Characterization of Pathogenic and Endophytic Fungal Species Associated with Pokkah Boeng Disease of Sugarcane

Abstract

Pokkah Boeng is a serious disease of sugarcane, which can lead to devastating yield losses in crop-producing regions, including southern China. However, there is still uncertainty about the causal agent of the disease. Our aim was to isolate and characterize the pathogen through morphological, physiological, and molecular analyses. We isolated sugarcane-colonizing fungi in Fujian, China. Isolated fungi were first assessed for their cell wall degrading enzyme capabilities, and five isolates were identified for further analysis. Internal transcribed spacer sequencing revealed that these five strains are <i>Fusarium</i>, <i>Alternaria</i>, <i>Phoma</i>, <i>Phomopsis</i>, and <i>Epicoccum</i>. The <i>Fusarium</i> isolate was further identified as <i>F. verticillioides</i> after Calmodulin and EF-1α gene sequencing and microscopic morphology study. Pathogenicity assay confirmed that <i>F. verticillioides</i> was directly responsible for disease on sugarcane. Co-inoculation of <i>F. verticillioides</i> with other isolated fungi did not lead to a significant difference in disease severity, refuting the idea that other cellulolytic fungi can increase disease severity as an endophyte. This is the first report characterizing pathogenic <i>F. verticillioides</i> on sugarcane in southern China.