Ethylene-influenced flower opening and expression of genes encoding Etrs, Ctrs, and Ein3s in two cut rose cultivars

Exogenous ethylene inhibits floral opening in cut rose (Rosa hybrida) cv. Kardinal and slightly promotes opening in cv. Samantha. We investigated ethylene production following short exposure to exogenous ethylene, and the expression of ethylene receptor genes (ETR) and genes in the ethylene signal transduction pathway (CTR and EIN3).In cv. Kardinal the ethylene production rate was much higher than in cv. Samantha, following ethylene treatment. The expression of ETR fragments was not much affected by ethylene in cv. Kardinal but was up-regulated in cv. Samantha. Data from the literature suggest that ETR is a negative regulator. The up-regulation of ETR, after ethylene treatment, indicates that the sensitivity to ethylene is down-regulated in Samantha but not in Kardinal. No clear effect of ethylene was found on the expression of fragments of CTR and EIN3 genes. It is concluded that the inhibition of floral opening in cv. Kardinal, and its absence in cv. Samantha, can apparently be explained by a differential effect of ethylene on the expression of genes for the ethylene receptor.