RESUMO
Cold acclimation in plants involves a very complex molecular response, with the regulation of many different genes and metabolic pathways. In this work fifteen cypress (Cupressus sempervirens) genes putatively regulated during cold exposure were isolated and their expression was studied in five cypress genotypes, along 15 days of treatment at 3 degrees C. Treated samples of shoots were collected from four year old cypress seedlings and a subtractive hybridization approach (PCR-Select) was performed after mRNA extraction. Fifteen genes were selected according to sequence similarities after a GenBank search and their expression was studied using Real-time PCR. Among these genes, five (ELIP, aquaporin, dehydrin and two cold-induced proteins) and four (oleosin, chlorophyll a/b-binding protein, oxidoreductase and rubisco activase) resulted respectively up- and down-regulated by the treatment in all tested genotypes. Finally, three genes (metal-binding protein, nodulin-like protein and beta-amylase) showed remarkable different pattern among genotypes. A consistent relationship was found between the cold regulation of the genes studied and their putative function, suggesting the existence of different cold response pathways in cypress. The possible roles of the low temperature-regulated sequences and of the individual expression differences during cypress cold acclimation are proposed and discussed.
