Strategies of Gene Action in Arabidopsis during Hypoxia

Abstract

Different plant species vary widely in their degree of tolerance to anaerobic stress. The precise molecular mechanisms underlying such tolerance are unknown, but both enzymes of the alcoholic fermentation pathway, pyruvate decarboxylase and alcohol dehydrogenase, are strongly induced during conditions of low oxygen. We have isolated two adh and two pdc genes in Arabidopsis thaliana (L.)Heynh. The patterns of expression of these genes have identified two sets of alcoholic fermentation pathway genes, each of which might play a different role in the adaptive response of the plant to anoxia. One set is strongly induced by low oxygen stress mainly in the roots, while the other set is expressed constitutively in both roots and leaves. Arabidopsis also has two haemoglobin genes, only one of which is induced by hypoxia. We are investigating the components of the signal transduction pathways leading to adh and pdc induction. Implications of our findings for metabolic engineering of plants to improve flooding tolerance are discussed.