Controlling Flower Senescence by Inducing Expression of etr1-1, a Mutant Ethylene Receptor

Flowers of ethylene-sensitive ornamental plants transformed with etr1-1, a mutant ethylene receptor first isolated from Arabidopsis, are known to have longer shelf lives.  However, since ethylene plays a role throughout growth and development, plants constitutively expressing the transgene show a variety of defects including poor germination, poor root growth and high susceptibility to disease.  If the mutant receptor is expressed under the control of a specific promoter, a more targeted effect can be achieved.  Previous workers have successfully used tissue-specific promoters for this purpose.  An even more focused response could be achieved using an inducible promoter system, which would allow expression of etr1-1 to be initiated at the desired time and stage of development. We have generated petunia plants in which the etr1-1 mutant protein is over-expressed under the control of a chemically-inducible promoter (GVG).  The plants develop normally, and the life of the flowers is almost doubled when the plants or excised flowers are exposed to low concentrations of the inducer chemical (dexamethasone).  We are now testing other chemical induction systems including one that responds to low concentrations of alcohol, which may offer a viable approach to commercial application of our findings.