Expression of ethylene receptor and transcription factor genes, and ethylene response during flower opening in tree peony (Paeonia suffruticosa)

Tree peony (Paeonia suffruticosa) is a well known traditional ornamental plant in China and cut flowers of tree peony have potential market value. To understand the involvement of ethylene in the cut flowers opening at the transcription level of ethylene signaling, we isolated two partial cDNAs encoding ethylene receptor Ps-ETR1-1 (GenBank accession no. EU526838) and transcription factor Ps-EIN3-1 (GenBank accession no. EU526839) from tree peony flower petals, and studied the effects of exogenous ethylene and 1-methylcyclopropene (1-MCP), an ethylene action inhibitor, on the expression of Ps-ETR1-1 and Ps-EIN3-1 during vase life. Northern blot analysis revealed that Ps-ETR1-1 and Ps-EIN3-1 exhibited constitutive levels during untreated flower opening, and they responded significantly to ethylene and 1-MCP treatments. In contrast with the control, the levels of Ps-ETR1-1 mRNA in petals were substantially inhibited by both ethylene and 1-MCP, and remained at nearly unchangeable level throughout flower development. Expression of Ps-EIN3-1 was strongly inhibited by ethylene and slightly induced by 1-MCP during flower opening and senescence. These results suggest that the Ps-ETR1-1 and Ps-EIN3-1 genes and their resultant protein may be involved in the ethylene sensitivity and responses of tree peony cut flowers.