2018 ASHS Annual Conference

In cut roses, the primary factors determining the longevity vary depending on flower sensitivity to ethylene. While the vase life of ethylene-sensitive cultivars is shortened by water stress, that of ethylene-insensitive cultivars is strongly related to ethylene synthesis. In this study, we characterized the nature of the ethylene sensitivity changes in four rose cultivars, which have different sensitivities to the hormone. In addition, we determined the impacts of ethylene binding and synthesis inhibition on flower senescence and gene expression using 1-methylcyclopropene (1-MCP) and aminoethoxyvinylglycine (AVG). Cut roses were treated either singly with 1 μL·L⁻¹ 1-MCP (+M) or simultaneously with 1 mM AVG and 1-MCP (A+M) for 12 h. After +M or A+M treatments, the flowers were subsequently exposed to ethylene. The relationship between the mRNA levels of ethylene biosynthesis, receptor, and signaling genes and the degree of ethylene sensitivity were determined during flower development and senescence. The results showed that A+M effectively maintained chlorophyll fluorescence emission (Fv/Fm) levels and water balance, and consequently prolonged the vase life of cut flowers in both ethylene-sensitive and -insensitive cultivars. In contrast, the cut flowers treated only with ethylene showed an early failure of water relations and shorter vase life. Both +M and A+M suppressed the expression of ethylene biosynthesis (RhACS2 and RhACO1) and receptor genes (RhETR1-5) in cut roses, although A+M was more efficient than +M. The expression of RhCTR1 and RhCTR2 was not consistently influenced by ethylene, however, was enhanced by +M and A+M. We also observed that the mRNA levels of RhEIN3-1, RhEIN3-2, and RhEIN3-3 were highly reduced by +M and A+M in ethylene-sensitive cultivars. These results contribute to better understanding about the relation between flower senescence and ethylene sensitivity as well as postharvest treatments of the ethylene antagonists.