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

The mutated carnation ethylene receptor gene Dc-ETR1nr was introduced into Torenia fournieri Lind. This gene contains a missense mutation causing conversion of a Pro(36) residue of the carnation ethylene receptor protein Dc-ETR1 to Leu(36), 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 wildtype plants. These results indicate that transgenic plants expressing Dc-ETR1nr have reduced ethylene sensitivity, resulting in inhibition of autocatalytic ethylene production and flower senescence.