Salinity stress induced tissue-specific proteins in barley seedlings.
Protein changes induced by salinity stress were investigated in two barley cultivars, California Mariout, a salt-tolerant variety and Prato, a salt-sensitive variety. Rapidly growing young barley seedlings were exposed to NaCl and the newly synthesized proteins were resolved on two dimensional polyacrylamide gels following isoelectric focusing or nonequilibrium pH gradient gel electrophoresis in the first dimension. Salinity induces distinct protein changes in root and shoot tissues. In roots, the salinity effects are identical in both cultivars. First, salinity modulates the synthesis of two different sets of proteins, one of which is elevated, and the other, depressed. Second, six new proteins are induced all of which are low in molecular weight, 24 to 27 kilodaltons, with an isoelectric point range of 6.1 to 7.6. In contrast to roots, salinity induces cultivar-specific shoot proteins. Five new shoot proteins are induced whose molecular weights and isoelectric points fall within the range of 20 to 24 kilodaltons and 6.3 to 7.2, respectively. Three of the newly induced proteins are unique to Prato. In addition, salinity inhibits the synthesis of a majority of shoot proteins. The new proteins produced in roots and shoots are unique to each tissue and their induction is apparently regulated coordinately during salinity stress.
Ramagopal
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United States Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, California 94710.