Identification and characterization of Fusarium commune, a causal agent of lotus rhizome rot

Lotus rhizome rot is one of the most important diseases affecting lotus production, leading to heavy economic losses in Japan. In this study, a causal agent of lotus rhizome rot in Yamaguchi prefecture, Japan, were identified as Fusarium commune based on their morphology and nucleotide sequences of EF-1α, HistonH3, and mtSSU. The inoculation tests showed that plants inoculated with F. commune isolated from lotus were more affected than those inoculated with strains from other hosts (tomato, turnip, and komatsuna) and soil in wheat fields. This result shows that particular strains of F. commune have virulence for lotus plants. Whole genome sequencing of the lotus-infecting F. commune revealed 20 effector candidates, including SIX4 and SIX9 homologs. Of these genes, 10 were expressed only in the roots of lotus but not in minimal medium. In particular, g3613 was specifically maintained in lotus-infecting F. commune, suggesting that this gene may be one of the candidate determinants of the host specificity of F. commune for lotus plants.