CHARACTERIZATION OF A SPINACH GENE RESPONSIVE TO LOW-TEMPERATURE AND WATER-STRESS

The characterization of a cDNA for an 85 kDa spinach protein, CAP85 (cold acclimation protein) that is responsive to cold acclimation and water stress is described. Both transcript and protein levels are increased during cold acclimation and water stress. A novel characteristic of CAP85 is the presence of an 11 amino acid, lysine-rich repeat, common to Group 2 LEAs (late embryogenesis abundant proteins), which is included within a larger repeating motif present in 11 copies. Two other motifs of 8 and 16 residues are also found in three and four copies, respectively. CAP85 like other dehydrins and cold-regulated polypeptides remains soluble upon boiling. Protein blot analyses indicate that CAP85 protein is expressed in all aerial tissues as well as in roots. RNA blots show the presence of mRNA for the 85 kDa protein in leaf, petiole, and root tissue. Cell fractionation studies suggest that CAP85 is predominately found in the cytosol.