ETHYLENE AND VEGETATIVE DEVELOPMENT

The past decade has witnessed a tremendous increase in our understandi ng of the role of ethylene in plant development. Genes encoding enzyme s of the ethylene biosynthesis pathway have been isolated, allowing th e manipulation of endogenous ethylene levels in intact plants. In para llel, a collection of ethylene mutants was obtained by using a simple response assay. This resulted in the identification of several genes i nvolved in ethylene signal transduction. The data obtained using these new tools have allowed long-standing hypotheses to be tested, while g aining novel insight into the function of ethylene in development. Rec ent molecular evidence supported the existence of an intense hormonal cross-talk during plant growth. Numerous processes are controlled by e thylene in it close interaction with auxin, and often it was impossibl e to differentiate between auxin and ethylene effects. Molecular-genet ic tools are now allowing the dissection of these interactions. Ethyle ne does not seem essential for many developmental processes. Neverthel ess, it is of crucial importance for survival in most species as it oc cupies a key position in the developmental response mechanisms of plan ts under mechanical stress.