文心蘭ascorbate peroxidase 對阿拉伯芥在中高溫生長下對於開花機制的調控功能

Molecular function of Oncidium ascorbate peroxidase on thermal-induced flowering process in Arabidopsis thaliana

黃柏睿(Bo-Ruei Huang)

指導教授 ： 葉開溫

國立臺灣大學/生命科學院/植物科學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.01067

摘要

南西文心蘭 (Oncidium Gower ramsey) 是亞洲的重要經濟花卉。前人研究指出，維他命C對於開花調節扮演著負調節的角色，然而，文心蘭生長在日／夜溫度30/25˚C較生長於25/20˚C環境中，明顯有較高的開花比例。因為較高的生長溫度可以有效地誘導維他命C過氧化氫酶 (OgAPX)的基因表現量與提高其活性，進而使大量的維他命C (ascorbate)被消耗掉。為了解維他命C在熱誘導開花中所扮演的角色，我們在阿拉伯芥中大量表現OgAPX。結果發現，轉殖植物(OgAPXOE)在22˚C的生長環境下，其形態上與野生型(control)並無顯著差異。然而提高其生長溫度至30˚C時，發現其較野生型有提早開花與較少的葉綠素累積。利用microarray分析受熱與維他命C共同影響的基因，發現這些基因主要種類為：氧化還原酶(oxidoreductase)、老化、防禦、訊號傳遞以及轉錄因子。進一步利用real-time PCR檢測下述之基因表現量，包括AtMYB70、At3g30720、參與circadian rhythms以及含有AP2-domain等基因。結果顯示，這些基因在較高的生長溫度中的表現情量確實較高／較低。而這些基因於vtc1 (維他命C含量僅有野生型30%的突變株)也有類似的較高表現量，而在OgPMEOX轉植株 (大量累積維他命C的轉殖株)當中卻有較低的表現量，這些證據顯示這類基因表現確實是受到內生性維他命C的含量所調控。綜合所有結果，我們推論維他命C參與在熱誘導開花過程可誘發較上游的開花相關基因之表現，上述基因皆屬於目前所有已知開花調控機制的較上游調控因子，此外，我們亦推論:在熱誘導開花中，醣類(sugar/energy)亦可能具有調節開花機制之功能。

關鍵字

維他命C ； 過氧化氫酶熱誘導開花

並列摘要

Oncidium Gower ramsey is an economically important cutting flower in orchid industry. Mild increase of growth temperature is effective to promote Oncidum flowering, in example of elevating day/night temperature from 25˚C/20˚C to 30˚C /25˚C. Our previous studies have revealed that higher growth temperature also induced the expression of ASCORBATE PEROXIDASE (OgAPX) and resulted in the deprivation of ascorbate (AsA) level. In order to decipher the underlying role of AsA under thermal-regulated flowering, OgAPX was overexpressed in Arabidopsis. There was no significant change on morphology between transgenic and control plants when growing under 22˚C. The OgAPXOE transgenic plants exhibited precocious flowering and reduction of chlorophyll content compared with control when growing at 30˚C condition. Microarray analyses of transgenic and control plants growing at 22˚C condition displayed differential expression patterns of genes to plants growing at 30˚C in categories in oxidoreductase, senescence, defense, signal transduction and transcription factors. AtMYB70, AP2, circadian genes and At3g30720, which displayed up/down-regulated expression pattern under elevated growth temperature condition were further validated by quantitative RT-PCR. Moreover, their expression levels were
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associated with the endogenous AsA level and displayed up-regulation level in ascorbate-deficient mutant, vtc1, but down-regulated level in ascorbate-accumulated transgenic plants, OgPMEOX. Noteworthy, attenuated expression level of At3g30720 encoding qua-quine starch (QQS) which acting on starch biosynthesis, provides a regulatory function of AsA state on the cross-talk of thermal- and energy-regulated flowering. Taken together, our results bring about a genetic network of flowering mechanism orchestrated by the elevated growth temperature.

並列關鍵字

ascorbate peroxidase ； thermal-induced flowering

參考文獻

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