MOLECULAR-CLONING AND CHARACTERIZATION OF A CDNA-ENCODING A WATER-STRESS PROTEIN (WSP23) FROM WHEAT ROOTS

Plants respond to different environmental stress stimuli by rapid synthesis of stress proteins which arc hypothesized to have a protective function in cellular metabolism. The nucleotide sequence of a wheat (Triticum aestivwn L.) cDNA encoding one such protein, WSP23 whose transcripts rapidly accumulate during water stress is presented. Sequence analysis of this cDNA yielded a derived polypeptide, 231 amino acids in length, with a predicted molecular mass of 23 229 and isoelectric point (pI) of 10.8. The putative polypeptide is highly hydrophilic and has highly conserved amino acid repeats that are similar to several other water stress responsive proteins found in higher plants. Genomic Southern blot hybridization data suggest the presence of a small multigene family encoding these proteins in wheat. Coordinate expression of genes that encode three different groups of water stress proteins indicates that the molecular changes that occur in plants in response to water deficits may mimic the gene expression pattern that occurs during late embryo maturation stages.