Characterization of a rice gene showing organ-specific expression in response to salt stress and drought.

Protein changes induced by salinity stress were investigated in the roots of the salt-sensitive rice cultivar Taichung native 1. We found eight proteins to be induced and obtained partial sequences of one with a molecular mass of 15 kilodaltons and an isoelectric point of 5.5. Using an oligonucleotide probe based on this information, a cDNA clone, salT, was selected and found to contain an open reading frame coding for a protein of 145 amino acid residues. salT mRNA accumulates very rapidly in sheaths and roots from mature plants and seedlings upon treatment with Murashige and Skoog salts (1%), air drying, abscisic acid (20 microM), polyethylene glycol (5%), sodium chloride (1%), and potassium chloride (1%). Generally, no induction was seen in the leaf lamina even when the stress should affect all parts of the plant uniformly. The organ-specific response of salT is correlatable with the pattern of Na+ accumulation during salt stress.