Effect of Exogenous Spermidine on Salinity Tolerance with Respect to Seed Germination

Polyamines like putrescine, spermidine and spermine etc. are low molecular weight nitrogenous compounds that are produced by plants when subjected to various stress Conditions. Seeds of amaranthus, spinach, green gram, green peas and chick pea were grown in MS medium supplemented with various concentrations of NaCl. Among the five species amaranthus and spinach were found to be salt tolerant (50 mM NaCl), green gram and green peas (20 mM) were moderately tolerant and chick pea was least tolerant. When the seeds were inoculated in MS medium supplemented with different concentrations of NaCl and spermidine, all the seeds had germinated. This shows that spermidine helps in salinity tolerance, which is clearly shown by the increase in germination percentage. The protein content in young seedlings germinated in the medium containing spermidine also increased when compared to the control. This shows the possibility of an increase in the enzymes responsible for the metabolism of spermidine. The data obtained from this experiment will be of great importance for producing transgenic plants that are tolerant to salinity stress. Moreover, over expression of genes responsible for the synthesis of polyamines like arginine decarboxylase, spermidine synthase and spermine synthase will result in the production salinity tolerant transgenic plants.