Changes in Free Amino Acids and Stress Protein Synthesis in Two Genotypes of Green Gram under Salt Stress

摘要

Changes in the level of total and Free Amino Acid (FAA) and analysis of protein profiles on SDS-PAGE were investigated and compared in root and shoot tissues of two green gram (Phaseolus aureus) cultivars (T-44 and SML-32) differing in salt toleranceduring plant growth in the absence and presence of NaCl salinity. Total as well as individual FAA were found to increase progressively with growth in both the tissue and in both the cultivars under absence and the presence of salinity. The level of totaland individual FAA was more in shoot than in root during plant growth from day 1 to 5. Salt tolerant cultivar T-44 had significant higher (p<0.05) level of total as well as individual FAA than that of salt sensitive cultivar SML-32 in both the tissues in absence as well as in the presence of salt. In salt tolerant cultivar the increased accumulation of amino acid (AA) under salt stress was more pronounced in case of alanine, arginine, aspartic acid, glutamic acid, glutamine, phenylalanine and serine. Analysis of the protein profiles of root and shoot tissues of both the cultivars in absence and presence of salinity on SDS-PAGE revealed that in both tissues of salt tolerant cultivar T-44, 3 to 4 polypeptides (PPs) were specially synthesized while synthesis of some PPs increased under salt stress. Salt induced changes in protein profile in root and shoot of salt tolerant cultivar T-44 were mostly tissue specific. On the other hand no such salt specific proteins were synthesized under salt stress in salt sensitive cultivar SML-32. Correlation between the degree of salt tolerance of the cultivar and levels of AAs and those of stress protein synthesis has been discussed.