Kinetics of transcript and protein accumulation of a low-molecular-weight wheat LEA D-11 dehydrin in response to low temperature.

We studied the kinetics of induction of the wheat (Triticum aestivum L.) gene Wdhn 13, which encodes a predominantly cold-responsive protein belonging to the LEA D-11 dehydrin family. The deduced polypeptide WDHN 13 (MW = 12.8 kDa) represented the smallest dehydrin member in cereals with three lysine-rich K-segments. Purified WDHN 13 was boiling-stable due to its high hydrophilicity. Western blot analysis using the polyclonal anti-WDHN 13-antibody revealed a number of cross-reacting proteins in mature embryos and endosperms and in seedling leaves under normal temperature (25 degrees C), while a single major protein and a transcript were induced in response to low temperature (4 degrees C) in the leaves. An increase in the amount of mRNA was temporary with a peak occurring at day 3 to 5 of the low temperature treatment, while the protein accumulation proceeded with a significant time lag and continued until the end of the experiment (day 10). Steady-state levels of the transcript and protein were much higher in the leaves than in the roots of low temperature-treated seedlings and were apparently modulated by light/dark conditions. The light/dark modulation of the transcript and protein levels suggested stabilization of the mRNA under the low temperature condition. Genomic Southern blot analysis showed that Wdhn 13 is located on the homoeologous group 7 chromosomes, unlike all other wheat Dhn genes that are located on the group 6 chromosomes.