Signaling events in the hypoxic induction of alcohol dehydrogenase gene inArabidopsis

Expression of the alcohol dehydrogenase gene (ADH) of Arabidopsis is induce d during hypoxia. Because many plants increase their ethylene production in response to hyyoxic stress, we examined in this report whether ethylene is involved in the hypoxic induction of ADH in Arabidopsis. We found that the hyyoxic induction of ADH can lac partially inhibited by aminooxy acetic ac id, an inhibitor of ethylene biosynthesis. This partial inhibition can be r eversed by the addition of 1-aminocyclopropane-1-carboxylic acid, a direct precursor of ethylene. In addition, the hypoxic induction of the ADH gene i s also reduced in etr1-1 and ein2-1, two ethylene insensitive mutants in et hylene-signaling pathways, whereas the addition of exogenous ethylene or an increase in cellular ethylene alone does not induce ADH under normoxic con ditions. Kinetic analyses of ADH mRNA accumulation indicated that an ethyle ne signal is required for the induction of ADH during later stages of hypox ia. Therefore, we conclude that ethylene is needed, but not sufficient for, the induction of ADH in Arabidopsis during hypoxia.