GGS : Vol. 75 (2000) , No. 1 p.49-57

A cold-responsive wheat (Triticum aestivum L.) gene wcor14 identified in a winter-hardy cultivar `Mironovska 808'

Sergei Tsvetanov¹⁾, Ryoko Ohno¹⁾, Kanako Tsuda¹⁾, Shigeo Takumi¹⁾, Naoki Mori¹⁾, Atanas Atanassov²⁾ and Chiharu Nakamura¹⁾

1) Department of Life Science, Graduate School of Science & Technology, and Laboratory of Plant Genetics, Department of Biological and Environmental Science, Faculty of Agriculture, Kobe University
2) Institute of Genetic Engineering

A cDNA library was constructed from a cold-acclimated winter-hardy common wheat (Triticum aestivum L.) cultivar `Mironovska 808'. Using this library and a cold- and light-responsive barley cDNA clone cor14b as a probe, cDNAs of a homologous wheat gene wcor14 were isolated. Two identical cDNAs designated as wcor14a had an open reading frame encoding an acidic (pI = 4.71) and hydrophobic polypeptide with 140 amino acids (MW=13.5 kDa). The deduced WCOR14a polypeptide showed 70% identity with the barley chloroplast-imported COR14b and had a nearly identical N-terminal, putative chloroplast transit peptide of 51 amino acid residues. Another cDNA clone wcor14b was assumed to encode a polypeptide WCORb which had 5 substitutions and a frame shift in the C-terminal region as compared with WCOR14a. RACE PCR, genomic PCR and Southern blot analyses suggested that wcor14 and its related sequences constitute a small multigene family with and without an intron in the hexaploid wheat genome. Northern blot analysis showed that transcripts of wcor14 accumulated within 3-6 hours of cold acclimation at 4C and the level reached a maximum at day 3. The transcripts became non-detectable within 3 hours after de-acclimation at room temperature. Contrary to the barley cor14b, a similar level of wcor14 transcripts was detected under the continuous darkness. Neither treatment with NaCl, ABA nor dehydration induced its expression. Based on these results we conclude that wcor14 is a wheat orthologue of the barley cor14b and specifically induced by low temperature.