Alleviation of abiotic stress in Oryza sativa by the application of novel polyextremophilic plant growth promoting Bacillus

Abstract

Oryza sativa (rice or paddy) is a primary food crop that provides 21% of global human per capita energy and 15% of per capita protein. Yet, paddy cultivation faces numerous challenges like water scarcity, inappropriate use of fertilizers, soil salinization, heavy metal contamination, etc. which affects both its quality and yield. Recent changes in climate, demands the agricultural practices to cope with aforementioned environmental adversities without hampering yield. Therefore, the use of polyextremophilic plant growth promoting bacteria (PPGPB) in paddy cultivation can be a sustainable solution that would not only enhance productivity but also alleviate the effects of these environmental stresses in the plants.With this background, this study investigates the role of 5 polyextremophilic PGPB strains Bacillus subtilis BRAM_G1, Bacillus subtilis BRAM_G2, Bacillus subtilis BRAM_G3 isolated from high-altitude waters of Ganges at Gangotri and Mesobacillus subterraneus BRAM_Y2 and Brevibacillus parabrevis BRAM_Y3 in not only stimulating the growth of Oryza sativa PB1692, in normal conditions and in presence of abiotic stress factors like 5% salt, 30 ppm Arsenic and drought, but also in the alleviation of the stress responses in the plants when subjected to these stresses. It was observed while in presence of stress parameters, the plants showed stunted growth, degraded chlorophyll and little to no yield, the PPGPB treated stress setups showed remarkable improvements in vegetative, biochemical as well as reproduction. The metagenome studies showed colonization of the bacterial inoculants, in the treated soils proving that the PPGPB treatment can enhancing growth and alleviate abiotic stress in paddy.