Isolation and evaluation of Bacillus subtilis RSS-1 as a potential biocontrol agent against Sclerotinia sclerotiorum on oilseed rape

Abstract Sclerotinia stem rot caused by sclerotiorum is one of the most important diseases oilseed rape in world. Because absence resistant varieties and disadvantages chemical control, application antifungal microbes has become an eco-friendly effective measure to control this disease. In study, Bacillus subtilis strain RSS-1, isolated from soil samples, was identified based on morphological, physiological biochemical tests, DNA gyrase subunit A ( gyrA ), gyrB , DNA-directed RNA polymerase beta rpoB ) rpoC gene sequence analysis. It significantly inhibited mycelial growth sclerotial production S. vitro . greenhouse experiments, all three tested concentrations (10 6 10 7 8 cfu mL −1 cell fermentation broth culture filtrate reduced severity sclerotinia P < 0.05). RSS-1 more at reducing disease when applied 24 h before inoculation with than post inoculation, suggesting that should be as a prophylactic rather curative biological agent. Colonization tests indicated population density rapeseed leaves decreased 0.05) over days. However, could stably colonize rhizospheric 30 Challenge showed activities polygalacturonase cellulase accumulation oxalic acid during infection. These results suggest potential agent for controlling rape.