Compositions and methods for the modification of physiological responses 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 protein that modifies sensitivity to ethylene 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, modulates expression of the selected protein and selectively modulates ethylene sensitivity in the plant cell. This modulation in the expression of the protein 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.