The long range goal of this research is to elucidate the molecular and cellular mechanisms by which the phytohormone ethylene regulates development in higher plants, specifically the activation of genes during ethylene-induced ripening of fruit. A number of ripening-induced genes including a cytochrome P-450 oxidase have been identified. This ripening-induced P-450 is the first plant P-450 to be characterized at the molecular level and is designated cyp71A1. The functional role of the cytochrome P- 450 in ripening fruit is unknown and is one of the primary objectives of the research proposed. In addition, cellular and genetic regulatory elements responsible for P-450 gene activation during ripening are being identified. The specific objectives are: (1) characterize the substrate specificity of the cyp71A1 gene product in a heterologous expression system, (2) identify the cis-acting elements that confer ethylene regulation on the cyp71A1 gene through transient expression assays of modified promoter/reporter constructs, and (3) characterize potential trans-acting factors which specifically bind to the upstream elements of the cyp71A1 gene. This research begins to unravel the series of biochemical events leading to ripening in avocado. Ripening is a poorly understood process of enormous economic importance in agriculture, as well as an excellent model system for how hormones affect genes espression.
