Heterologous Expression of a Mutated Carnation Ethylene Receptor Gene, Dc-ETR1nr, Suppresses Petal Abscission and Autocatalytic Ethylene Production in Transgenic Torenia fournieri Lind.

Abstract

The mutated carnation ethylene receptor gene Dc-ETR1nr was introduced into Torenia fournieri Lind. This gene contains a missense mutation causing conversion of a Pro36 residue of the carnation ethylene receptor protein Dc-ETR1 to Leu36, as occurs with the tomato mutant gene Never-ripe (Nr). Agrobacterium transformation of Torenia was performed, and four putative transgenic plants with Dc-ETR1nr were obtained. Real-time RT-PCR analysis confirmed Dc-ETR1nr mRNA expression in all transgenic plants. Unlike wild-type plants and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) transgenic plants, none of the transgenic plants showed flower abscission in response to ethylene treatment. Flower life in all Dc-ETR1nr transgenic plants following wounding or ethylene treatment was longer than that in wild-type plants. Levels of autocatalytic ethylene production in all transgenic plants following wounding or pollination treatment were lower than those in wild-type plants. These results indicate that transgenic plants expressing Dc-ETR1nr have reduced ethylene sensitivity, resulting in inhibition of autocatalytic ethylene production and flower senescence.