Genetic diversity and pathogenicity of Fusarium fujikuroi species complex (FFSC) causing sugarcane pokkah boeng disease in China

Abstract

Pokkah Boeng Disease (PBD), a sugarcane foliar disease, is caused by various Fusarium species within the Fusarium fujikuroi species complex (FFSC). In the current study, we investigated the diversity of Fusarium species associated with PBD in China. A total of 320 leaf samples displaying PBD symptoms were collected over ten consecutive years (2012-2021), during winter and summer, from six various sugarcane growing regions (Guangxi, Yunnan, Guangdong, Zhejiang, Hainan, and Fujian) in China. Phylogenetic analysis of Fusarium species is reconstructed using translation elongation factor 1-alpha (TEF-1α), DNA-directed RNA polymerase II largest subunit (RPB1), and second largest subunit (RPB2) multigene sequences. Evolutionary studies of these regions categorized the isolates into four FFSC species F. sacchari, F. proliferatum, F. verticillioides, and F. andiyazi. The identified isolates were tested for their pathogenicity, which developed irregular necrotic patches and rotting symptoms on the sugarcane plant after approximately 30 days. Symptoms that appeared during pathogenicity testing were consistent with those observed under field conditions. Each strain of the pathogenic Fusarium species belonged to different VCGs, and there was no affinity between VCGs. Our results contribute to understanding FFSC and accurately identifying Fusarium species associated with the sugarcane crop.