Isolation and expression analysis of an ethylene receptor gene Ps-ETR2 in tree peony cut flowers

Tree peony (Paeonia suffruticosa) is a well-known traditional flower with a broad market prospect in China. In order to understand the role of ethylene receptor genes in postharvest development of tree peony cut flowers, an ethylene receptor gene Ps-ETR2 was isolated and analysed in this study. An ethylene-sensitive cultivar ‘Luoyang Hong’ and an ethylene-insensitive cultivar ‘Xue Ying Tao Hua’ were selected to analyse the expression pattern of Ps-ETR2 gene in their petals at different developmental stages by quantitative real-time PCR. The results showed that the expression pattern of Ps-ETR2 exhibited significant differences between the two cultivars. During cut flower postharvest development, Ps-ETR2 transcripts in petals of the ethylene-sensitive ‘Luoyang Hong’ cultivar showed a rapid and obvious rise at the pre-opening stage followed by a gradual decline from pre-opening to full opening stage, and then reached the highest level of mRNA accumulation at senescence. Unlike this pattern, Ps-ETR2 transcripts in petals of the ethylene-insensitive ‘Xue Ying Tao Hua’ cultivar remained at a relatively low-level during flower opening, and only increased a little when petals wilted. These results suggest that the Ps-ETR2 gene and its resultant protein may be involved in the regulation of ethylene sensitivity of tree peony cut flowers. This may provide a theoretical basis for further research on the molecular mechanism of ethylene-mediated opening and senescence of tree peony cut flowers.