Alleviation of salinity-induced damage on wheat plant by an ACC deaminase-producing halophilic bacterium Serratia sp SL-12 isolated from a salt lake

Plant growth promoting bacteria (PGPB) with 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase) activity can be used to ameliorate salt stress in plants. The aim of this study was to characterize a salt-tolerant PGP bacterium Serratia sp. SL-12 isolated from a salt lake, and to evaluate its capability to promote growth in wheat plants (Triticum aestivum L) under conditions of salt stress. The isolate SL-12 exhibited other plant growth promoting properties such as the production of indole-3-acetic acid, and enabling solubilization of inorganic phosphate. An analysis of fatty acid composition of the isolate grown at different salt concentrations (150-200 mM) indicated that salt concentration strongly influenced the fatty acid composition, and increased the proportion of unsaturated fatty acids. Inoculation of SL-12 into wheat plants growing under salt stress (150200 mM NaCl) resulted in a significant increase in plant growth, as measured by parameters such as shoot/root length, fresh/dry weight, and photosynthetic pigment accumulation. In addition, application of isolate SL-12 decreased the levels of Na+ by (65 %) and increased the uptake of K+ by (39 %), indicating a role in maintaining ionic homeostasis, and minimizing toxic ionic effects in host wheat plants. The growth of wheat seedling under salinity stress was improved by SL-12 by inducing accumulation of osmolytes such as total soluble sugar and total protein content, while reducing the salt-induced malondialdehyde content. This has been found by other researchers. The present study indicates the potential of isolate SL-12 as a biofertilizer for enhancing the growth of wheat and other crops under salt stress conditions.