Biological control of sheath blight disease of rice by siderophore producing rhizobacterial strains and their role in efficient mobilisation of micronutrients from soil

Abstract

Four siderophore producing rhizobacterial strains Bacillus cereus Z2-7, Enterobacter sp. B41 strain SPR7, Aeromonas hydrophila BPS10 and Enterobacter sp. BPS12 isolated from rice grown in saline soils were examined for induction of chitinases, glucanases and peroxideses (POX) in rice plants against sheath blight pathogen R. solani and mobilization of micronutrients from rice rhizosphere to straw and grain of rice plant. Atomic absorption studies indicated that rice plants preinoculated with Bacillus cereus Z2-7 have an increased uptake of zinc, copper and iron as compared to uninoculated control plants. High content of copper and iron were present in straw while high quantity of zinc was found in grains. Straw of rice plants inoculated with Enterobacter sp. B41 strain SPR7 contained highest Manganese content as compared to other treatments and uninoculated control plants. Gene expression analysis revealed enhanced levels of chitinase, peroxidase and glucanase expression in rice plants preinoclated with bacterial strains Z2-7 and SPR7 after 7 and 52 days of challenge inoculation with R. solani. Improved uptake of micronutrients and induction of defence enzymes in these plants resulted in an increase in yield of these plants as compared to rest of the treatments.