Amino-cyclopropane carboxylate (ACC) deaminase producing bacteria confer moisture deficit stress tolerance and enhance growth and yield of rainfed chickpea (Cicer arietinum L.)

Plant growth promoting rhizobacteria (PGPR) can confer stress tolerance to plants through a process referred as induced systemic tolerance (IST). Potential of 1-aminocyclopropane carboxylate (ACC) deaminase producing bacteria on mitigation of abiotic stresses in plants is well documented. In the present investigation, 35 rhizobacteria that can utilize ACC and grew well on liquid minimal medium with 3mM ACC are isolated from chickpea and studied for their potential for plant growth promotion. Moisture stress reduced the root biomass to the level of 40.6% compared to unstressed plants while inoculation of certain ACC deaminase producing bacteria restores the root development to the range of 5.42–30.21% over uninoculated control under stress. They can also help to retain relative water content (RWC) of stressed plants to 70.14%, significantly close to unstressed plants. Inoculation of ACC deaminase producing bacteria prevents the chlorophyll degradation by maintaining RWC in leaves under stressed environment. ACC-16, ACC-10, ACC-84 and ACC26 inoculated plants recorded highest total chlorophyll content i.e. >500 ug/g of leave tissues. Chickpea bacterizized with ACC deaminase bacteria recorded higher grain yield for two consecutive years under rainfed field condition. Above results indicated the potential of ACC deaminase producing bacteria on mitigating moisture deficit stress and hence, potential strains viz., ACC-10, ACC-16 and ACC-68 were selected and recommended for further evaluation under multilocation trails.