Effectiveness of Endophytic and Rhizospheric Bacteria from spp. in Controlling Damping-Off of Cabbage.

In this study, endophytic and rhizospheric bacteria were isolated from and from Oman, and their in vitro antagonistic activity against was tested using a dual culture assay. The promising strains were tested further for their compatibility and potential for plant growth promotion, biofilm formation, antifungal volatile organic compound (VOC) production, and the biological control of damping-off of cabbage ( L.) under greenhouse conditions. A total of 12 endophytic and 27 rhizospheric bacteria were isolated from spp. Among them, MPE1 showed the maximum antagonistic activity against in the dual culture assay, followed by MPE3 and MOR3 and MOR8. These bacterial isolates induced abundant morphological abnormalities in the hyphae of , as observed via scanning electron microscopy. The in vitro cross-streak assay showed that these bacterial isolates were compatible among themselves, except for MOR8 × MPE3. These antagonists released VOCs that restricted the growth of in an in vitro assay. These antagonistic bacteria released 2,4-dimethylheptane and 4-methyloctane as the predominant volatile compounds. Of the four antagonistic bacterial strains, MOR8 was capable of forming biofilm, which is considered a trait that improves the efficacy of rhizosphere inoculants. The results of the greenhouse experiments showed that the soil treatment with MPE1 showed the highest reduction (59%) in the incidence of damping-off in cabbage, evidencing its potential as a biological control agent for the management of this disease. Further research is needed to characterize the antifungal traits and activities of MPE1 and to assert its potential use against other soil-borne plant pathogens.