2017 ASHS Annual Conference

Although cut roses are classified as ethylene-sensitive flower species, the nature of the ethylene sensitivity changes in these flowers and its relationship with longevity have not been well characterized. In the present study, the relationships between longevity, ethylene sensitivity, and expression of ethylene biosynthesis genes were determined in 33 rose cultivars. Although cut roses were all harvested within a month in summer and kept under identical postharvest environments, the vase life of the examined cut roses showed 283% variation, ranging from 5.5 to 15.5 days. Ethylene primarily accelerated petal wilting, which is the main senescence symptom shortening the longevity. qRT-PCR analysis revealed that among five ethylene biosynthesis genes, RhACO1 showed the most distinct expression patterns in response to ethylene. The results also showed that ACS genes were differentially expressed in response to ethylene, and that only RhACS2 and RhACS4 are induced by ethylene and during flower senescence. Correlation analysis revealed that the primary factors that affect the vase life vary depending on ethylene sensitivity of the cultivars. The vase life of ethylene-sensitive cultivars was strongly correlated to RhACO1 transcript level. In contrast, the vase life of ethylene-insensitive cultivars was mostly shortened due to an early failure of water relations, as a consequence of the decreased hydraulic conductance of stems and water loss via transpiration. The results from the current study suggested that postharvest treatments for improving the longevity of cut roses should be differently applied based on the ethylene sensitivity of the cultivars.