ACC Deaminase Containing Plant Growth Promoting Agrobacterium larrymoorie Strain MZ 3-ABF Confers Tolerance to Drought Stress in Chickpea (Cicer arietinum L.) Seedlings

Plant growth-promoting rhizobacteria (PGPR) that produce 1-aminocyclopropane-1-carboxylate (ACC) deaminase can alleviate plant growth constraints caused by water scarcity. In the present study, six PGPR strains were evaluated to produce several plant growth promoting, and ACC deaminase enzyme isolated from the rhizosphere soil of Chickpea (Cicer arietinum) in arid regions of Telangana State, India. According to their 16S rDNA sequencing analysis, only one of the six strains, MZ 3-ABF, belongs to Agrobacterium larrymoorie. A drought tolerance experiment revealed two PGPR strains with high phosphate solubilization, nitrogen fixation, indoleacetic-3-acid (IAA), and ACC deaminase enzyme secretion potential were constrained to only MZ 3-ABF and MZ 5-ABF. One strain MZ 3-ABF was chosen for use in a pot experiment to assess their growth-promoting effects on chickpea under drought conditions. This PGPR strain inoculation into chickpea seedlings was expected to alleviate the overall growth inhibition caused by drought stress. The inoculation was thought to have the greatest growth-promoting effects. Inoculation with strain MZ 3-ABF altered plant height, root length, dry biomass, and net photosynthetic rate of leaves, allowing chickpea seedlings to cope with drought better. They had an indirect effect on the biochemical and physiological properties of chickpea seedlings in order to alleviate drought stress. These findings suggest that the MZ 3-ABF PGPR may be useful for effectively weakening the growth inhibition caused by drought in chickpea. The strain could also be used as effective bioinoculant to maintain pea quality.