Characterization and Expression of a Water Stress Responsive Gene from a Seashore Plant Calystegia soldanella

Abstract

We have isolated a cDNA clone encoding the 28.3 kDa polypeptide homologous to tomato ASR (abscisic acid, stress and ripening) proteins from Calystegia soldanella. The protein, designated CSASR (C. soldanella ASR), had not only homologous regions to ASR, but also a unique insert consisting of 139 amino acids containig eight repeating motifs of 11- to 12-mer amino acids near the N-terminus. The strongest expression of the CSASR gene was observed in anther, but no expression was found in the other parts of the flower in C. soldanella. The gene was also expressed in the leaf, but little in the stem or the root. Drought, NaCl, abscisic acid, and cold induced the gene expression in the shoot, but only drought and cold induced expression in the root. The findings suggested that CSASR might be involved in the reproduction and survival of C. soldanella in the seashore.