Regulation of Ethylene- and Senescence-related Genes in Pot Carnation Flowers during Flower Senescence

We investigated differences in flower longevity, ethylene production, and ethylene sensitivity among pot carnation cultivars by quantitative PCR analysis. The flower life of 'Polaris' was significantly longer than that of 'Ariel' (control cultivar), 'Orange Duo', and 'Lemon Soft'. The flowers of 'Polaris' produced little ethylene, and had low expression of the ethylene biosynthesis genes DcACS1 and DcACO1. The transcript levels of senescence-related (SR) genes DcCP1, DcbGal, and DcGST1 increased in petals of 'Ariel', 'Orange Duo', and 'Lemon Soft' at senescence, but were very low in 'Polaris'. These results suggest that the low ethylene production in 'Polaris' is caused by low expression of DcACS1 and DcACO1, as in long-life flowers of the cut carnation cultivars 'Miracle Rouge' and 'Miracle Symphony'. The ethylene sensitivity of 'Orange Duo' and 'Lemon Soft' was lower than that of both 'Ariel' and 'Polaris'. Petals of 'Orange Duo' and 'Lemon Soft' wilted, and inrolled more slowly than those of 'Ariel' and 'Polaris', despite the upregulation of ethylene biosynthesis genes (DcACS1 and DcACO1), DcCP1, DcbGal, DcGST1, and DcEIL3 in petals of all cultivars upon application of exogenous ethylene. These results imply that only the components related to the inrolling of petals are altered in these ethylene-insensitive cultivars.