Abstract:
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 (150–200 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.