CONTROL OF TARGETED TURNOVER OF KEY ETHYLENE HORMONE SIGNALING PATHWAY PROTEINS TO MODULATE ETHYLENE SENSITIVITY IN PLANTS

摘要

A gene expression system for controllable expression of ethylene response in aplant cell includes an activationcassette comprising a DNA-binding domain that recognizes a response element;an ecdysone receptor ligand binding domain; andan activation domain; and a target cassette comprising an inducible promoter,which comprises, in operative association, the responseelement and a minimal promoter responsive to the activation domain. Theinducible promoter controls the expression of anucleic acid sequence that encodes a selected regulatory protein that modifiessensitivity to ethylene of certain signal proteins inthe plant. Interaction among the components of the activation cassette andtarget cassette, when in a plant cell, in the presence ofan inducing composition, increases expression of the selected regulatoryprotein, and in turn decreases expression and accumulationof the signal protein in the plant, thereby and decreasing ethylenesensitivity in the plant cell. This increase in the expressionof the regulatory protein, particularly in the presence of ethylene, iscontrolled by the timing, the concentration and the duration ofthe application of the inducing composition. Transgenic plant cells, tissues,organs and entire plants are provided, which in thepresence of the inducing composition control ethylene sensitivity. Ethylenesensitivity and/or ethylene production in such transgenicplants and tissues may be controlled for purposes of manipulating ripening,flower senescence and other ethylene sensitivefunctions of the plant.