Diverse mechanisms for the regulation of ethylene-inducible gene expression.

We have investigated the mechanism of action of the plant hormone ethylene by analyzing the expression of ethylene-inducible genes isolated from tomato (Lycopersicon esculentum). We have found that the expression of each cloned gene is regulated by ethylene in a unique manner. That is, for certain genes ethylene affects transcriptional processes, while for another gene it affects both transcriptional and post-transcriptional processes. Furthermore, induction of gene transcription by ethylene is organ specific for one gene, while for others it is not. In addition, we have measured gene expression as a function of ethylene concentration and have found that each gene displays a unique ethylene dose-response curve. Our results suggest that ethylene modulates gene expression by a variety of mechanisms.