Transformation of carnation with genes related to ethylene production and perception: towards generation of potted carnations with a longer display time

Potted carnation (Dianthus caryophyllus L. cv. Lillipot) plants were transformed with cDNAs for carnation 1-aminocyclopropane-1-carboxylate (ACC) synthase (DC-ACS1, s/aACS transgenes) or ACC oxidase (DC-ACO1, s/aACO transgenes) in sense or antisense orientation or mutated carnation ethylene receptor cDNA (DC-ERS2′) by Agrobacterium-mediated gene transfer. The presence of acetosyringone at 100 μM in media for shoot culture prior to leaf explant preparation and preculture of Agrobacterium in addition to the conventional method of addition to media for infection and coculture, and the use of water instead of nutrient media for infection and coculture increased the transformation efficiency to 4.0% compared to the 0.1% obtained by the conventional method. PCR analysis as well as Southern blot analysis confirmed the integration of the ethylene-related transgenes. Leaflet segments of cultured shoots of some lines transformed with s/aACO transgenes had less activity to convert ACC to ethylene than that of the non-transformed control plant, indicating that the integrated s/aACO transgenes reduced the expression of endogenous ACC oxidase gene (DC-ACO1) in the cultured shoots.