Stress-buster Enterobacter sp. alleviates salinity stress in Cajanus cajan together with impacting its rhizospheric microbiome

The global food crisis has triggered a rapid evolution of the agricultural sector to meet requisite demand. Deciphering interactions in the soil microbiome would lead to sustainable agricultural development. 1-ami-nocyclopropane-1-carboxylic acid (ACC) deaminase producing bacteria help plants to counter stress. The study's primary aim was to demonstrate that an indigenous ACC deaminase producer from Cajanus cajan rhi-zosphere successfully facilitated stress alleviation in the fields, and distinctly shaped the rhizospheric micro -biome. Enumeration and screening of ACC deaminase positive bacteria was performed based on gnotobiotic root elongation assay and plant growth promoting properties. Selected strains were used for plant growth experiments (in laboratory and subsequently under natural conditions), to assess their performance under salinity stress by estimating plant growth parameters and stress marker levels. Plant growth was enhanced by the application of ACC deaminase positive bacteria, leading to increases of 55% in shoot length, 58% in root length, and 233% in dry weight. The treatment also enhanced levels of enzymatic antioxidants SOD, POX, and catalase by 18%, 12% and 26%, respectively. Deleterious H2O2 levels were reduced by 31%, and lipid peroxida-tion (MDA) levels decreased by 55%. ACC deaminase positive bacteria promoted plant health as demon-strated by 73% and 52% increase in levels of plant chlorophylls a and b, respectively, accompanied with a reduction in MDA levels by 55%. Plant growth and salinity stress alleviation by the most potent ACC deami-nase positive Enterobacter strain was further validated in the field, leading to a 2-fold enhancement in grain yield. 16S rRNA amplicon sequencing of rhizospheric samples revealed distinct shifts in bacterial communi-ties upon addition of Enterobacter strain. The study demonstrated the successful application of an indigenous ACC deaminase positive bacterial strain isolated from field, tested in laboratory and applied back in the field. Additionally, it characterized the impact of such an addition on the rhizospheric microbiome. (c) 2023 SAAB. Published by Elsevier B.V. All rights reserved.

Automated summary

The global food crisis has driven the agricultural sector to evolve rapidly to meet demand. Understanding the interactions in the soil microbiome is crucial for sustainable agricultural development. This study aimed to demonstrate the stress-alleviating effects of indigenous ACC deaminase producing bacteria in Cajanus cajan rhizosphere, and their influence on the rhizospheric microbiome.