cDNA sequence analysis and expression of two cold-regulated genes ofArabidopsis thaliana

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Abstract
The DNA sequences of cDNAs for twocor (cold-regulated) genes ofArabidopsis thaliana L. (Heyn) were determined. One cDNA (approximately 70% full-length) corresponds to acor gene, designatedcor47, that encodes a 47 kDa hydrophilic polypeptide. The data indicate that COR47 has amino acid sequence homology with Group II LEA (lateembryogenesisabundant) proteins, a class of proteins that accumulate late in embryo development. DNA sequence analysis of a second cDNA (containing the complete protein coding sequence) indicates that it represents acor gene, designatedcor6.6, that encodes an alanine-rich 6.6 kDa hydrophilic polypeptide. COR6.6 is almost identical to KIN1, a cold-regulatedArabidopsis gene that has been suggested to have amino acid sequence similarities with type I fish antifreeze proteins (S. Kurkela, M. Franck, Plant Mol Biol 15: 137–144, 1990). Northern analysis indicated that transcripts forcor47 andcor6.6 do not accumulate to high levels in late-developing embryos or fresh mature seeds as is typical oflea gene transcripts. The similarities and differences between COR and LEA proteins are discussed as are their possible roles in freezing and drought tolerance.