Abstract
Little is known about transcription factors involved in the sugar-signal response in plants. We used microarray of Arabidopsis thaliana for extensive analysis of sugar-induced changes in levels of mRNAs. Among many sugar-regulated genes identified, genes for transcription factors were selected for further analyses. One of the mRNAs that were the most extensively induced by sucrose was AtMYB90 which has been recently shown to regulate the expression of genes for anthocyanin biosynthesis. Although glucose also induced AtMYB90, 2-deoxyglucose or ABA was ineffective. Expression of many genes for bZIP factors was regulated by sucrose, and some of them also responded to ABA, suggesting that they are involved in the ABA-dependent sugar-response pathways. Unlike these, levels of mRNAs for AtbZIP22 and AtbZIP63 changed rapidly after treatment with sucrose, and they did not respond significantly to ABA. In addition, sugar-induced changes in levels of mRNAs for these bZIPs occurred in the presence of cycloheximide.
