TISSUE-SPECIFIC MODULATION OF SALT INDUCIBLE GENE-EXPRESSION - CALLUSVERSUS WHOLE-PLANT RESPONSE IN SALT-TOLERANT ALFALFA

We have cloned several genes that were continuously induced by salt in our salt-tolerant alfalfa (Medicago sativa L.) callus. These genes we re not induced by 24 h salt stress in the parent salt-sensitive cell l ine. To investigate the extent to which salt-stress regulation of thes e genes is influenced by a program of tissue specific regulation we ha ve characterized another one of the cloned cDNAs, pA18 determined the expres sion of the transcript it encodes and compared its salt-inducib le tissue-specific expression in plants with MsPRP2. another single or low copy gene induced in the salt-tolerant cells. While pA18 and MsPR P2 transcripts are similarly salt-induced in callus, comparisons of ti ssue specific expression between these two genes demonstrate that regu lated tissue specific expression can override salt inducibility of mRN A accumulation for individual genes.