Identification and characterization of three novel cold acclimation-responsive genes from the extremophile hair grass Deschampsia antarctica Desv.

Deschampsia antarctica Desv. is the only monocot that thrives in the harsh conditions of the Antarctic Peninsula and represents an invaluable resource for the identification of genes associated with freezing tolerance. In order to identify genes regulated by low temperature, we have initiated a detailed analysis of its gene expression. Preliminary 2-D gels of in vivo-labeled leaf proteins showed qualitative and quantitative differences between cold-acclimated and non-acclimated plants, suggesting differential gene expression. Similarly, cold-acclimation-related transcripts were screened by a differential display method. Of the 38 cDNAs initially identified, three cDNA clones were characterized for their protein encoding, expression pattern, response to several stresses, and for their tissue-specific expression. Northern blot analysis of DaGrx, DaRub1, and DaPyk1 encoding a glutaredoxin, a related-to-ubiquitin protein, and a pyruvate kinase-like protein, respectively, showed a distinct regulation pattern during the cold-acclimation process, and in some cases, their cold response seemed to be tissue specific. All three transcripts seem to be responsive to water stress as their levels were up-regulated with polyethyleneglycol treatment. DaRUB1 and DaPyk1 expression was up-regulated in leaf and crown, but down-regulated in roots from cold-acclimated plants. The significance of these results during the cold-acclimation process will be discussed.