Generation and Screening of Azospirillum Mutants With Improved Plant Growth-Promoting Effects using Ion-beam

Azospirillum sp. B510 (B510) is a diazotrophic endophyte that has been isolated from the stems of a rice plant. Increased seed production by B510-colonized rice plants was demonstrated under greenhouse, paddy field, and laboratory conditions. Moreover, rice plants inoculated with this bacterium induced resistance against rice blast disease and rice blight disease. Recently, we reported that the colonization of B510 of rice plants is affected by nitrogen fertilizers. In this study, we conducted mutagenesis using ion beam irradiation and screened B510 mutants with improved beneficial phenotypes for plant growth-promoting rhizobacteria (PGPR) such as motility. In conclusion, we set up the condition of Ion-beam mutagenesis for a PGPR Azospirillum sp. B510. In a first screening, we successfully isolated 510 mutants with enhanced motility, suggesting that the Ion-beam mutagenesis is a useful tool to generate mutants with ideal characteristics