Indian Journal of Scientific Research

The experiments were conducted to examine the effect of choline and glycine-betaine, synthesized and accumulated in alfalfa plants (Medicago sativa L.) on alleviation of sodium chloride stress. Soil salinity (1.2 to 12.0 mScm⁻¹ ECe) brought about an accumulation of these osmolytes. However, they presented their net destruction upon relief of stress. Choline was found to accumulate in the range of 24.88⁻¹ 6.32 μ mol g⁻¹ fresh wt. and varied to rising extent under increasing ECe levels of sodium chloride. Glycine betaine levels were high (>64.90 μ mol g⁻¹ fresh wt.) under 1.2 mScm⁻¹ ECe and went on increasing gradually with rising salinity levels (4–12 mScm⁻¹ ECe). The synthesis and accumulation of both the osmolytes in shoot always exceeded roots. Discrete spots of glycine and serine as observed on thin layer chromatograms revealed that the synthesis of choline and glycine betaine could take place de novo from carbon precursor ethanol amine-a product of amino acid serine. It may be suggested that the estimated metabolic cost of glycine betaine synthesis via choline approached the cost of protein turn over. Since both these osmoprotectants might mitigate the toxicity of sodium chloride salt, it may presumably be consistent with their adaptive value. A search for their synthesizing potential variability is warranted.