Transformation of Campanula carpatica to alter flower colour and ethylene sensitivity

Abstract

SUMMARYThis study is the first report of gene manipulation to alter flower colour in the genus Campanula. The experiment was designed using Campanula carpatica ‘Improved Blue Uniform’ (IBU) with two main purposes: to generate a red flower colour by down-regulation of delphinidin production through RNAi silencing of the flavonoid 3′, 5′ hydroxylase (F3′5′H) gene, and to improve vase-life by inducing insensitivity to ethylene using the ethylene-resistant 1–1 (etr1–1) gene. Three independent transgenic lines were obtained after genetic transformation via Agrobacterium tumefaciens strain GV3101. Southern blot analysis was performed to determine the integrated T-DNA copy number, and reverse transcription-polymerase chain reactions (RT-PCR) were performed to evaluate expression of the F3′5′H and flavonoid 3′ hydroxylase (F3′H) genes. An ethylene sensitivity test was conducted to evaluate the tolerance of the transformed plants to exposure to ethylene. Southern blot analysis revealed the integration of two or three T-DNA copies in each of the three transformed lines. The flower colour of the transformed lines was not visually altered, and expression of the F3′5′H and F3′H genes in all three transformed and in non-transformed lines was confirmed by RTPCR. Although all flowers on non-transformed Campanula plants were senescent 6 d after exposure to ethylene, 63.3% of the flowers on transgenic line 11–213 and 86.4% of the flowers on transgenic line 21–1 survived. The ethylene sensitivity test showed that transformed plants exposed to ethylene showed a significant delay in senescence compared to non-transformed plants.