ABSCISIC-ACID INDUCES THE ALCOHOL-DEHYDROGENASE GENE IN ARABIDOPSIS

Exogenous abscisic acid (ABA) induced the alcohol dehydrogenase gene ( Adh) in Arabidopsis roots. Both the G-box-1 element and the GT/GC moti fs (anaerobic response element) were required for Adh inducibility. Me asurement of endogenous ABA levels during stress treatment showed that ABA levels increased during dehydration treatment but not following e xposure to either hypoxia or low temperature. Arabidopsis ABA mutants (aba1 and abi2) displayed reduced Adh mRNA induction levels following either dehydration treatment or exogenous application of ABA. Low-oxyg en response was slightly increased in the aba1 mutant but was unchange d in abi2. Low-temperature response was unaffected in both aba? and ab i2 mutants. Our results indicate that, although induction of the Adh g ene by ABA, dehydration, and low temperature required the same cis-act ing promoter elements, their regulatory pathways were at least partial ly separated in a combined dehydration/ABA pathway and an ABA-independ ent low-temperature pathway. These pathways were in turn independent o f a third signal transduction pathway leading to low-oxygen response, which did not involve either ABA or the G-box-1 promoter element.