Promotion of Wheat Growth under Salt Stress by Halo tolerant Bacteria Containing ACC deaminase

Abstract

Salinity is a major abiotic stress that reduces cro p productivity in arid and semiarid soils. About 25% of the country's arable land is af fected by different levels of salt. A considerable part of this land is under wheat culti vation each year as the country's most important crop. ACC deaminase producing bacteria in crease plant resistance to stress condition by reducing stress ethylene in a variety of environmental stresses such as salinity. In this study, 167 halotolerant bacterial strains were isolated from the saline habitats and screened for growth at different NaCl concentrations. These halotolerant bacterial strains were then tested for 1 AminoCyclo propane-1-Carboxylic acid (ACC) deaminase activity. Among six isolates of halotoler ant bacteria containing ACC deaminase, the K78 strain produced the highest leve l of this enzyme. Phylogenetic analysis of the 16S rRNA gene sequence of this bact erium indicated that this strain belonged to Bacillus mojavensis . Inoculation of Bacillus mojavensis to salt stressed wheat plants produced an increase in root and shoot weigh t, chlorophyll content, and nutrient uptake in comparison with the un-inoculated soils. In summary, this study indicates that the use of ACC deaminase-producing halotolerant bac teria mitigates salinity stress effects on growth of wheat plants by reducing salt-stress-i nduced ethylene production. Keywords : Abiotic stress, Bacillus , Ethylene production, Root growth , Salinity.