Diversity and antagonistic potential of apoplastic bacteria against Ralstonia pseudosolanacearum race 4 causing bacterial wilt of ginger

Abstract

Bacterial wilt caused by Ralstonia pseudosolanacearum race 4 is a devastating disease of ginger, for which almost all control measures met with limited success. In this study, 150 bacteria isolated from the apoplastic fluid of ginger were screened for antagonism against R. pseudosolanacearum both in vitro and in planta and shortlisted six isolates which were further characterized for biocontrol and plant growth promoting traits. The promising isolates were identified as Bacillus subtilis (IISRGAB 5), B. marisflavi (IISRGAB 43), B. licheniformis (IISRGAB 107), Agrobacterium tumefaciens (IISRGAB24), Micrococcus luteus (IISRGAB 48) and Staphylococcus haemolyticus (IISRGAB 146). Green house evaluation against R. pseudosolanacearum, by seed priming and soil drenching showed that B. licheniformis strain GAP107–MTCC 12725, was able to reduce bacterial wilt incidence up to 67%. Hence, this bacterium was identified as a suitable candidate for developing a potential biocide for the management of bacterial wilt in ginger.