Alleviation of salt stress by Halomonas sp. and osmolytes in Zea mays
Level of osmolytes accumulation to a variable extent in bacteria and plants is associated with the salt tolerance. We hypothesized that two previously isolated salt tolerant strains, Halomonas meridiana (PAa6) and Halomonas aquamarina (RT2), found to stimulate the growth of wheat also have the ability to accumulate osmolytes. These strains can favour plant growth due to their endogenous osmolyte accumulation. To ascertain this, strains were checked for osmolyte accumulation under salt stress. Growth and osmolyte accumulation of inoculated and non-inoculated seeds of the economically significant plant, Zea mays Var. EV.90, was recorded. Seeds were sown in soil supplemented with and without exogenous proline and glycine betaine and salt stress for 15 days. The results show that strains can accumulate osmolytes (preferably glycine betaine) at higher salt stress. Inoculation and exogenous osmolytes (10 mM) improved the plant growth at higher salt stress. However, concurrent application had an amplified effect. Endogenous level of osmolyte (preferably glycine betaine) on the fresh weight basis was significantly higher and improved bacterial and plant growth under stress. We conclude that accumulation of osmolytes in bacteria and plants significantly stimulated growth and protect them from the adverse effect of salt stress. This can be an alternate economic approach to increase crop productivity.
Key words: Osmolyte, glycine betaine, proline, salt stress.