Characterization of the ethanol-inducible alc gene-expression system in Arabidopsis thaliana

Controlled expression of transgenes in plants is key to the characterizatio n of gene function and the regulated manipulation of growth and development . The alc gene-expression system, derived from the filamentous fungus Asper gillus nidulans, has previously been used successfully in both tobacco and potato, and has potential for use in agriculture. Its value to fundamental research is largely dependent on its utility in Arabidopsis thaliana. We ha ve undertaken a detailed function analysis of the ak regulon in A. thaliana . By linking the alcA promoter to beta -glucuronidase (GUS), luciferase (LU C) and green fluorescent protein (GFP) genes, we demonstrate that alcR-medi ated expression occurs throughout the plant in a highly responsive manner. Induction occurs within one hour and is dose-dependent, with negligible act ivity in the absence of the exogenous inducer for soil-grown plants. Direct application of ethanol or exposure of whole plants to ethanol vapour are e qually effective means of induction. Maximal expression using soil-grown pl ants occurred after 5 days of induction. In the majority of transgenics, ex pression is tightly regulated and reversible. We describe optimal strategie s for utilizing the ak system in A. thaliana.