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.