Characterization of a Cold-Regulated Wheat Gene Related to Arabidopsis cor47.

The cDNA clone pWG1 represents a gene, designated cor39, from Triticum aestivum L. cv Winoka (a winter wheat) that is related to a cold-regulated Arabidopsis thaliana L. (Heyn) gene, cor47. In vitro transcription/translation experiments in conjunction with DNA sequence analysis indicated that cor39 encodes a hydrophilic polypeptide of 39 kD (isoelectric point of 7.5), designated COR39. The polypeptide is composed primarily of two sequences, each of which is repeated six times. One sequence, which is lysine rich, occurs in COR47 (the polypeptide encoded by Arabidopsis cor47) and group II LEA proteins, polypeptides hypothesized to have roles in desiccation and drought tolerance (J. Baker, C. Steele, L. Dure III [1988] Plant Mol Biol 11: 277-291). The second sequence, which is glycine rich, occurs in some, but not all, group II LEA proteins. Southern analysis indicated that wheat has a number of loci related to cor39. Transcripts of about 3.3, 1.5, and 0.8 kb that hybridize with cor39 were found to accumulate in leaf, root, and crown tissues of cold-acclimated plants; they accumulated rapidly in response to low temperature and returned quickly to low levels when plants were returned to normal growth temperature. Transcripts hybridizing with cor39 were present at relatively high levels in wheat seeds and accumulated in plants in response to exogenous application of ABA and water stress. The similarities in expression of wheat and Arabidopsis cor genes and possible functional relationships among COR39, COR47, and LEA proteins are discussed.