A wheat cold-regulated cDNA encoding an early light-inducible protein (ELIP): its structure, expression and chromosomal location.

Sequencing and computer analysis revealed that a wcr (wheat cold-regulated) cDNA, wcr12, contained a 525 bp open reading frame encoding a polypeptide of 174 amino acids. The deduced WCR12 protein had a high sequence similarity with Early light-inducible proteins (ELIPs) which are known as nuclear-encoded chloroplast proteins induced by light stress. The accumulation of wcr12 transcripts was induced by low temperature below 8 degrees C and was also increased under a high light flux of 1,000 microEm-2 s-1, which are typical expression patterns of the genes for ELIPs in other plants. The dramatic increase in the level of wcr12 transcripts was detected at 4 degrees C even under a low light condition (50 microEm-2 s-1) and the level of transcripts became 20-fold higher than the control at 20 degrees C under a moderate light condition (250 microEm-2 s-1). Surprisingly, the accumulation of wcr12 mRNAs was also induced by cold treatment alone at 4 degrees C in the darkness. The level of wcr12 transcripts accumulated in the darkness at 4 degrees C reached the same level as that under a high light flux at 20 degrees C. These results indicate that light is not essential for the accumulation of wcr12 transcripts at a low temperature. To determine the chromosomal location of wcr12 gene, we performed Southern analysis using the nullitetrasomic lines. The data showed that the wcr12 gene or related homologues are located on the chromosomes of homoeologous group-5 in wheat.