Analysis of differential expression of barley ESTs during cold acclimatization using microarray technology

Genomics adds a new dimension to genetic analysis, shifting the focus from the study of a single gene to the whole genome. We have successfully applied the genomics approach based on microarray to the study of genes involved in barley responses to cold stress. About 900 EST clones from barley were obtained from a cDNA library of cold acclimatized leaves of cv. Nure and arrayed, and gene expression analysis done on cold acclimatized vs. control plants. The system allowed for reliable detection of differences in mRNA expression levels, and was confirmed by the finding that numerous previously reported cold-related genes were differentially expressed in treated and untreated plants when evaluated in our arrays. The expression profiles of a sample of genes analysed by the array were confirmed by quantitative RT-PCR. Previously, identification of novel plant genes was achieved considering a few genes at a time; now many genes can be found as up- or down-regulated based on a one step procedure. Many of the genes we found to be up- or down-regulated do not have an assigned function. This includes 15 of the 78 up-regulated and 8 of the 45 down-regulated clones. Our results add new genes to the group of cold-regulated genes and provide the opportunity to better understand the complex mechanism of stress tolerance.