Genes commonly regulated by water-deficit stress in Arabidopsis thaliana.

Cellular water-deficit stress triggers many changes in gene expression which can be used to define the response of a plant to an environmental condition. Microarray technology permits the study of expression patterns of thousands of genes simultaneously, permitting a comprehensive understanding of the types and quantities of RNAs that are present in a cell in response to water-deficit stress. The expression of specific genes was compared in three different experiments designed to understand changes in gene expression in response to water-deficit stress. Surprisingly, there was a relatively small set of genes that were commonly induced or repressed. There were 27 genes commonly induced and three commonly repressed; 1.4% and 0.2% of the genes analysed in common to all three experiments. The induced genes fell into six different functional categories: metabolism, transport, signalling, transcription, hydrophilic proteins, and unknown. The three commonly repressed genes indicated that repression of gene expression supported a frequently observed response to water-deficit stress, decreased growth. A more detailed analysis of genes involved in cell wall metabolism, indicated that there was a global decrease in expression of genes that promote cell expansion.