CHARACTERIZATION OF THE ETHANOL-INDUCIBLE ALC GENE-EXPRESSION SYSTEM FOR TRANSGENIC PLANTS

We describe a chemically induced gene control mechanism for plants bas ed on the ALCR transcription factor and alcA promoter of Aspergillus n idulans, which we have called the aic system. Ethanol, the chemical in ducer, is not toxic at levels required for induction, and can be appli ed to the plants by spraying, root drenching and addition to liquid gr owth media. The ale system is very sensitive to ethanol and the induct ion is rapid; 0.01% (1.7 mM) ethanol in liquid growth media initiates chloramphenicol acetyl transferase (CAT) reporter gene expression with in 4 h, with maximal expression occurring after 4 days. In the complet e absence of ethanol, there is no detectable expression of CAT, nor do we observe induction in plants subjected to wound, cold or drought st ress, or following treatment with either salicylic acid or methyl jasm onate. However, extreme anoxia resulting in elevated levels of alcohol dehydrogenase activity in both roots and leaves gave substantial indu ction of CAT in leaves but not in roots. We believe that the ale syste m will have broad utility in the exogenous control of plant gene expre ssion in pure science and that it also has considerable potential in a griculture.