探討OgTPS1基因對於調控文心蘭生長與 開花所扮演的功能

Abstract

文心蘭(Oncidesa)為台灣外銷切花出口最大宗之花卉作物，但其開花與從營養 生長轉為生殖生長之機制尚未明瞭。前人研究發現，當文心蘭長時間處於中高環境 溫度(30°C)之下將會被誘導開花，因植物體內會大量累積活性氧化物質(reactive oxygen species; ROS)，並活化了維生素C-榖胱甘肽循環(AsA-GSH cycle)，誘導文 心蘭SQUAMOSA PROMOTER BINDING PROTEIN-LIKEs(OgSPLs)表現，進而誘導 下游開花基因Flowering locus T(FT)、LEAFY(LFY)與APETALA 1 (AP1)表現，最終使文心蘭開花。近期研究指出，海藻糖-6-磷酸鹽生成酶(trehalose-6-phosphate synthase;TPS)會生合成海藻糖-6-磷酸鹽(T6P)，而T6P會作為一種信號分子，去協助植物抵 抗逆境、對養分脅迫進行反應與影響開花時間，並且T6P的含量與蔗糖含量呈現正 相關性。為了探究OgTPS1與前人發現之文心蘭中高環境溫度誘導開花路徑之關係， 並且探討OgTPS1與蔗糖之關係，我們將文心蘭處理了中高環境溫度、buthionine sulfoximine(BSO)、glutathione disulfide(GSSG)、glutathione(GSH)以及蔗糖(sucrose)， 隨後利用qPCR檢測相關基因之表現情況。從結果顯示，OgTPS1會受中高環境溫度、 BSO、GSSG、GSH以及蔗糖之誘導表現。同時檢測了OgSPLs與FT、LFY以及AP1 後，發現OgSPLs與FT、LFY以及AP1會受到中高環境溫度、BSO、GSSG與蔗糖處 理提高表現情況，反之受到GSH所抑制表現。關於此實驗結果，說明OgTPS1會協 助植物抵抗氧化逆境，並且其參與了前人發現之文心蘭中高環境溫度誘導開花途 徑，同時也可作為糖類誘導開花途徑的關鍵因子。

The mechanism of flowering and phase transition from vegetative to reproductive stage is a mysterious event in Oncidesa. In previous study, we found that high ambient temperature-induced flowering pathway in Oncidesa. This floral induction in response to thermal stress is associated with a significantly increased reactive oxygen species (ROS) level and active Ascorbate acid(ASA)-Glutathione(GSH) pathway. The redox signal will induce Oncidesa SQUAMOSAPROMOTER BINDING PROTEIN-LIKEs(OgSPLs), and then it will elevate the expression level of Flowering locus T(FT), LEAFY(LFY) and APETALA 1(AP1). Recent studies indicate that trehalose-6-phosphate(T6P), which is synthesized by trehalose-6-phosphate synthase(TPS), will be a signal molecule to influence stress tolerance and regulate flowering time. Researches point out that increasing sucrose levels will positively affect the abundance of T6P in plants. As mentioned above, we want to know whether OgTPS1 will be involved in high ambient temperature-induced flowering pathway in Oncidesa or not. We also want to explore the relationship between OgTPS1 and sucrose. Afterwards, we use high temperature, glutathione disulfide(GSSG), glutathione(GSH), buthionine sulfoximine(BSO) and sucrose to treat Oncidesa, and then we use qPCR to detect the expression level of several genes. Studies reveal that OgTPS1 is induced by high-ambient temperature, GSSG, GSH, BSO and sucrose. On the other hand, OgSPLs, FT, LFY and AP1 were induced by high- ambient temperature, GSSG, BSO and sucrose, and repressed by GSH. Taken together, OgTPS1 may confer plants with stress resistance, and is involved in high ambient temperature-induced flowering pathway. Moreover, OgTPS1 acts as a key factor in sugar induced flowering pathway.