Bio-prospecting fluoride tolerant bacteria for their optimistic contribution in instigating resilience against fluoride stress in Oryza sativa L.

Abstract

In recent years, the effects of fluoride (F) pollution in numerous ecosystems such as groundwater, soil, etc. Have become a major issue worldwide. This increase in F pollution is a direct consequence of the unbridled use of fertilizers in agricultural and several other human activities that require immediate and appropriate action. Therefore, this manuscript reveals important findings on the efficacy of bacteria isolated from agricultural fields in central Chhattisgarh in manifesting resistance to F and in reversing the F-induced oxidative damage in susceptible Oryza sativa L, (Var. MTU1010). Chronic exposure of Oryza sativa L. to sodium fluoride (NaF) (50 mg L⁻¹) severely impeded growth and various physiological parameters such as germination percentage, biomass and root and shoot length and stimulated the formation of reactive oxygen species (ROS), which enhanced electrolyte leakage and formation of cytotoxic products like malondialdehyde. To this end, potential bacterial strains, namely MT2A, MT3A, MT4A, and Du3A were isolated, screened for various plant growth promoting (PGP) traits and used to explore their efficiency to mitigate F toxicity in Oryza sativa L. in vivo. The seedlings inoculated with the bacterial strains showed significant development as evidenced by an increase in root and shoot length, biomass and chlorophyll content. Additionally, inoculation of these strains in combination with F stress significantly decreased oxidative stress by increasing the expression of protective genes encoding antioxidant enzymes and boosted agronomic traits remarkably. Overall, the manuscript demonstrates the pivotal role played by the isolated bacteria in abating ill effects of F in the Oryza sativa L. seedlings and proves their potential as protective bioagents against F stress.