A 16S rRNA amplicon approach to the structural and functional diversity of bacterial communities associated with horse gram crop for drought mitigation and sustainable productivity.

Abstract

In this study, 16S rRNA amplicon sequencing analyses were performed to determine the diversity of the bacterial community present in the soil, rhizosphere region, root nodules and seeds of the horse gram plant. We observed the dominance of Proteobacteria, Actinobacteria, Firmicutes, Acidobacteria, Bacteroidetes, Planctomycetes and Gemmatimonadetes across all four domains of the horse gram plant. For community analyses, the significance of the alpha diversity was estimated using the Shannon index, Simpson index and Chao1 index, which revealed no significant difference among the samples. However, the estimation of the beta diversity indicated a significant difference among the samples, with p < 0.001 and R2 =1. A strong positive correlation was found between the rhizosphere and root nodule samples. Comparative genomics of the 16S rRNA gene showed that ammonium-oxidizing metabolism (amoA), nitrite-reducing metabolism (nirK) and nitrogen-fixing metabolism (nifH) were prominent mechanisms in all samples. The genes involved in the biosynthesis of amino acids, purine metabolism and nitrogen metabolism were identified as the key genes associated with the functional traits of microbial domains in horse gram. The culturable microbes associated with horse gram can be used as a substitute for synthetic fertilizers to maintain soil fertility and ecological health in agricultural practices. Determining the survival strategies of bacterial communities that positively respond to multiple gate selection helps in understanding the structural diversity and functional traits primarily focused on the development of beneficial microbial consortium for promoting plant growth.