关键词: 牡丹, 切花, 离区, 乙烯, 生长素, 脱落

Abstract: 【Objective】The aim of this study was to explore the physiological mechanisms of petal wilting and abscission during the senescence of cut tree peony flowers, so as to provide theoretical basis for better development of storage and preservation technology of cut tree peony flowers.【Method】The cut flowers were pretreated with deionized water (CK), 20 μL·L^-1 ethylene antagonist Correxian (AVB) , 20 μL·L^-1 ethylene releasing agent ethephon (CEPA) or 20 μL·L^-1 Correxian for 1 h, respectively, followed by 20 μL·L^-1 ethephon 1 h (AVB+CEPA). The flowers were then placed in individual vases filled with distilled water. The morphology of the petals absciss zone cells were observed by using a microscope. The petal anti-falling ability were determined by using the tensile test during the vase cutting process.The physiological effects of different pre-treatments were observed respectively using the physiological and biochemical methods to determine the ethylene and auxin metabolism, the absciss zone hydrolysis-related enzyme activities and the relative expressions of PsETR1, PsCTR1, PsEIN3, PsERF1, PsYUCCA10, PsPIN1, PsPME1, PsPG1 and PsBG1 genes. 【Result】The results showed that the basal petal of the cut tree peony 'Luoyanghong' had a clear separation layer structure. AVB significantly delayed the occurrence of ethylene climacteric in cut flowers, and decreased the ethylene release peak by 34.9% (P<0.05), while the petal anti-falling ability was improved. The activities of polygalaturonase (PG), β-glucosidase (BG) and the expressions of PsPG1 and PsBG1 genes at the base of the petals absciss zone were reduced, which delayed the senescence process of cut tree peony flowers, thus significantly extended its vase life. Nevertheless, the exogenous CEPA significantly accelerated the release rate of endogenous ethylene in the petals, increased the activities of IAA oxidase (IAAO), PG and BG, and accelerated the senescence of the absciss zone cells in the petals of cut flowers, reduced the petal anti-falling ability thus promoted its wilting and falling. Meanwhile, the vase life and the optimal viewing period of AVB+CEPA composite pretreatment were not much different from those control, and so CEPA could partially offset the physiological effects of AVB. 【Conclusion】For the ethylene sensitive cut tree peony 'Luoyanghong', endogenous auxin is involved in the process of ethylene promoting the abscission of petal absciss zone cells. The control of ethylene is the basic way to improve the quality of cut flowers ‘Luoyanghong’.

Key words: tree peony, cut flowers, absciss zone, ethylene, auxin, abscission