The agricultural crops are often affected by the scarcity of fresh water. Seasonal drought is a major constraint on Northeast Indian agriculture. Almost 80% of the agricultural land in this region is acidic and facing severe drought during the winter period. Apart from classical breeding and transgenic approaches, the application of plant-growth-promoting bacteria (PGPB) is an alternative strategy for improving plant fitness under stressful conditions. The 1-aminocyclopropane-1-carboxylate (ACC) deaminase-producing PGPB offer drought stress tolerance by regulating plant ethylene levels. The aim of the present study was to evaluate the consortium effect of three ACC-deaminase producing rhizobacteria – Ochrobactrum pseudogrignonenseRJ12, Pseudomonas sp.RJ15 and Bacillus subtilisRJ46 on drought stress alleviation in Vigna mungo L. and Pisum sativum L. Consortium treatment significantly increase seed germination percentage, root length, shoot length, and dry weight of treated plants. An elevated production of reactive oxygen species scavenging enzymes and cellular osmolytes; higher leaf chlorophyll content; increase in relative water content and root recovery intension were observed after consortium treatment in comparison with the uninoculated plants under drought conditions. The consortium treatment decreased the ACC accumulation and down-regulated ACC-oxidase gene expression. This consortium could be an effective bio-formulator for crop health improvement in drought-affected acidic agricultural fields.

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Aim Environmental stresses such as water deficit induced stress are one of the major limiting factors in crop production. However, some plant growth-promoting rhizobacteria (PGPR) can promote plant growth in such adverse condition. Therefore, the objective was to isolate rhizospheric bacteria from Phaseolus vulgaris L. growing in a drought-affected soil and to analyze its plant growth promoting (PGP) efficacy to black gram (Vigna mungo L.) and Bhut jolokia (Capsicum chinense Jacq.). Whole-genome sequencing of the potential bacteria was targeted to analyze the genetic potential of the isolate as a plant growth-promoting agent. Methods and results The isolate Enterobacter asburiae EBRJ12 was selected based on its PGP efficacy, which significantly improved plant growth and development. The genomic analysis revealed the presence of one circular chromosome of size 4.8 Mb containing 16 genes for osmotic stress regulation including osmotically inducible protein osmY, outer membrane protein A precursor ompA, aquaporin Z, and an operon for osmoprotectant ABC transporter yehZYXW. Moreover, the genome has a complete genetic cluster for biosynthesis of siderophore Enterobactin and siderophore Aerobactin. The PGP effects were verified with black gram and Bhut jolokia in pot experiments. The isolate significantly increased the shoot length by 35.0% and root length by 58.0% of black gram, while 41.0% and 57.0% of elevation in shoot and root length were observed in Bhut jolokia compared to non-inoculated plants. Conclusions The EBRJ12 has PGP features that could improve the growth in host plants, and the genomic characterization revealed the presence of genetic potential for plant growth promotion.