Ethylene Biosynthesis

The suggestion that ethylene is involved in the responses of plants to stress is of no recent date and there are a multiplicity of publications over the last thirty years which tend to support this view. It must be said however that, almost in their entirety, the conclusions in such publications rest on correlations and inferences, which, no matter how logical, do not of themselves constitute proof of causal relationships. In the same context, while it may be a relatively easy task to show that imposition of a stress leads to, say, increased ethylene biosynthesis, it is much more difficult to demonstrate that these effects are specific. Equally, it is difficult to prove that the effect of stressinduced ethylene has an “adaptive” or “survival” value for the plant in relation to the tress. The purpose of this article is to provide a brief overview of the field and to attempt to assess whether, and to what extent, ethylene is involved in the responses of plants to stress.