Control of targeted turnover of key ethylene hormone signaling pathway proteins to modulate ethylene sensitivity in plants

Abstract

A gene expression system for controllable expression of ethylene response in a plant cell includes an activation cassette comprising a DNA-binding domain that recognizes a response element; an ecdysone receptor ligand binding domain; and an activation domain; and a target cassette comprising an inducible promoter, which comprises, in operative association, the response element and a minimal promoter responsive to the activation domain. The inducible promoter controls the expression of a nucleic acid sequence that encodes a selected regulatory protein that modifies sensitivity to ethylene of certain signal proteins in the plant. Interaction among the components of the activation cassette and target cassette, when in a plant cell, in the presence of an inducing composition, increases expression of the selected regulatory protein, and in turn decreases expression and accumulation of the signal protein in the plant, thereby and decreasing ethylene sensitivity in the plant cell. This increase in the expression of the regulatory protein, particularly in the presence of ethylene, is controlled by the timing, the concentration and the duration of the application of the inducing composition. Transgenic plant cells, tissues, organs and entire plants are provided, which in the presence of the inducing composition control ethylene sensitivity. Ethylene sensitivity and/or ethylene production in such transgenic plants and tissues may be controlled for purposes of manipulating ripening, flower senescence and other ethylene sensitive functions of the plant.