Endophytic bacteria associated with cultivars of Brassica juncea and their antagonistic potentials against Alternaria brassicae

Abstract

The yield potential of Brassica juncea is constrained by many fungal diseases among which Alternaria blight poses a major challenge worldwide. Endophytic bacteria are increasingly recognized as a promising source of novel organic natural metabolites for a variety of biological activities. However endophytic bacteria belonging to the group Bacillus and fluorescent Pseudomonads are being reported as superior groups exploited for their role in combating phytopathogens. Therefore, the bacteria belonging to the above groups were primarily targeted for this study. In this study, fifty six endophytic bacteria were selectively isolated from seeds, roots and leaves of 20 different cultivars of Brassica juncea growing in various parts of North Eastern Region of India. Out of all isolates tested BS8, BS15, BS21 and FP13 show inhibition of 59.63%, 65.93%, 58.52% and 63.33 % respectively. When tested for functional properties, BS21 produced IAA as well as ammonia, BS15 and FP13 produced only Ammonia whereas BS8 solubilised Phosphate. BS8 (Bacillus cereus), BS15(Bacillus subtilis), BS21 (Bacillus subtilis) and FP13 (Pseudomonas fluorescens) were selected on the basis of antagonistic as well as plant growth promoting properties for formulating a microbial consortium and subsequent evaluation in the field.