Boosting the Biocontrol Efficacy of Bacillus amyloliquefaciens DSBA-11 through Physical and Chemical Mutagens to Control Bacterial Wilt Disease of Tomato Caused by Ralstonia solanacearum .

Bacterial wilt disease of tomato ( Solanum lycopersicum L.), incited by Ralstonia solanacearum (Smith), is a serious agricultural problem in India. In this investigation, chemical mutagenic agents (NTG and HNO 2 treatment) and ultraviolet (UV) irradiation have been used to enhance the antagonistic property of Bacillus amyloliquefaciens DSBA-11 against R. solanacearum UTT-25 towards an effective management of tomato wilt disease. The investigation established the fact that maximum inhibition to R. solanacearum UTT-25 was exerted by the derivative strain MHNO 2 -20 treated with nitrous acid (HNO 2 ) and then by the derivative strain MNTG-21 treated with NTG. The exertion was significantly higher than that of the parent B. amyloliquefaciens DSBA-11. These two potential derivatives viz . MNTG-21, MHNO 2 -20 along with MUV-19, and a wild derivative strain of B. amyloliquefaciens i.e.,DSBA-11 were selected for GC/MS analysis. Through this analysis 18 major compounds were detected. Among the compounds thus detected, the compound 3-isobutyl hexahydropyrrolo (1,2), pyrazine-1,4-dione (4.67%) was at maximum proportion in the variant MHNO 2 -20 at higher retention time (RT) of 43.19 s. Bio-efficacy assessment observed a record of minimum intensity (9.28%) in wilt disease and the highest bio-control (88.75%) in derivative strain MHNO 2 -20-treated plants after 30 days of inoculation. The derivative strain MHNO 2 -20, developed by treating B. amyloliquefaciens with nitrous acid (HNO 2 ), was therefore found to have a higher bio-efficacy to control bacterial wilt disease of tomato under glasshouse conditions than a wild-type strain.