Chitosan is an effective inhibitor against potato dry rot caused by Fusarium oxysporum

Fusarium dry rot was one of the most serious diseases of potato during storage. Biological control based on the use of natural bioactive compounds to suppress tuber diseases offer an attractive alternative. As a biopolymer, chitosan had broad-spectrum antimicrobial activity against various phytopathogens and could induce plant resistance to pathogens. Previous observations showed that chitosan displayed effective inhibition on potato dry rot caused by Fusarium sambucinum, Fusarium sulphureum, etc., however, little is known whether chitosan can suppress potato dry rot caused by Fusarium oxysporum. In this study, the mycelial growth and spore germination of F. oxysporum were significantly inhibited by chitosan, and the pathogenicity of F. oxysporum was reduced after treated by chitosan. Moreover, chitosan could enhance the susceptibility of F. oxysporum to environmental stresses and improve the potato resistance against F. oxysporum. The transcriptome analysis of F. oxysporum with or without chitosan indicated that total 4955 differentially expressed genes (DEGs) were identified, of which 2839 were up-regulated and 2116 were down-regulated. KEGG pathway and GO term analysis showed DEGs were mostly related to protein metabolism, stress tolerance and cell structure. These findings suggested chitosan might be a promising natural fungicide for the potato dry rot caused by F. oxysporum.