EVIDENCE FOR A ROLE FOR ATMYB2 IN THE INDUCTION OF THE ARABIDOPSIS ALCOHOL-DEHYDROGENASE GENE (ADH1) BY LOW-OXYGEN

The transcription factor AtMYB2 binds to two sequence motifs in the pr omoter of the Arabidopsis ADH1 gene. The binding to the GT-motif (5'-T GGTTT-3') is essential for induction of ADH1 by low oxygen, while bind ing to the second motif, MBS-2, is not essential for induction. We sho w that AtMYB2 is induced by hypoxia with kinetics compatible with a ro le in the regulation of ADH1. Like ADH1, AtMYB2 has root-limited expre ssion. When driven by a constitutive promoter, AtMYB2 is able to trans activate ADH1 expression in transient assays in both Arabidopsis and N icotiana plumbaginifolia protoplasts, and in particle bombardment of P isum sativum leaves. Mutation of the GT-motif abolished binding of AtM YB2 and caused loss of activity of the ADH1 promoter in both transient assays and transgenic Arabidopsis plants. These results are consisten t with AtMYB2 being a key regulatory factor in the induction of the AD H1 promoter by low oxygen.