https://scholars.lib.ntu.edu.tw/handle/123456789/139729
標題: | 文心蘭花朵中類胡蘿蔔色素合成基因之表達圖譜及其 Carotenoid Cleavage Dioxygenase (CCD)基因之功能性探討 The gene expression profile of carotenoid biosynthetic pathway and the functional role of Carotenoid Cleavage Dioxygenase (CCD) in Oncidium floral tissues |
作者: | 潘信銨 Pan, Hsin-An |
關鍵字: | 萳西文心蘭(Oncidium Gower Ramsey);香吉士文心蘭(Oncidium Gower Ramsey ‘Sunkist’);白玉文心蘭(Oncidium Gower Ramsey ‘White Jade’ );類胡蘿蔔素;CCD基因;Oncidium Gower Ramsey;Oncidium Gower Ramsey ‘Sunkist’;Oncidium Gower Ramsey ‘White Jade’;carotenoid;carotenoid cleavage dioxygenase | 公開日期: | 2011 | 摘要: | 香吉士(Oncidium Gower Ramsey ‘Sunkist’)與白玉(Oncidium Gower Ramsey ‘White Jade’ ) 為萳西文心蘭(Oncidium Gower Ramsey)的突變種,本研究目的在分析及研究這三者文心蘭中花色差異與類胡蘿蔔素形成機制之相關性及carotenoid cleavage dioxygenase 1 (OgCCD1s)、9-cis-epoxycarotenoid dioxygenase (OgNCED)生理生化功能。 首先利用高效液相層析儀鑑定香吉士文心蘭花朵中類胡蘿蔔素組成的種類與萳西文心蘭幾乎相同(lutein、violaxathin、9-cis-violaxathin和neoxanthin),但額外多出β-carotene;而在白玉文心蘭的花朵中偵測不到類胡蘿蔔素的累積。檢測ABA含量發現白玉文心蘭含量較高且經觀察有提早老化現象。分析九個參與類胡蘿蔔素生合成與代謝基因在花苞成熟時期的表達量,發現香吉士文心蘭中β-hydroxylase (OgHyb)與zeaxathin epoxidase (OgZep)的表現量比萳西文心蘭低,此結果可能是造成香吉士文心蘭花苞中累積β-carotene的原因;而白玉文心蘭中與類胡蘿蔔素生合成相關基因的表達與萳西文心蘭並無差異,但參與類胡蘿蔔素代謝的基因OgCCD1在白玉文心蘭中卻大量表現,此結果可能是造成白玉文心蘭花苞中類胡蘿蔔素無法累積的原因。利用基因槍將花苞專一表達啟動子(Pchrc)驅動OgCCD1基因的載體送入萳西唇辦組織中進行短暫性表現分析,發現類胡蘿蔔素會因OgCCD1的活化表現而被分解。進一步釣取OgCCD1啟動子進行甲基化特異PCR方法分析(Methylated-specific primer,MSP),發現OgCCD1啟動子在萳西文心蘭中有被甲基化的現象,而白玉文心蘭卻無此現象發生。由此證明OgCCD1的表達是白玉文心蘭花朵呈現白色的主因。 從萳西、白玉文心蘭花朵Lambda phage cDNA library中釣取五條OgCCD1家族成員。OgCCD1及OgNCED胞內定位結果顯示, OgCCD1表現於葉綠體細胞膜上及細胞質中,而OgNCED則表現於葉綠體內。比較對照組與大量表達OgCCD1s及OgNCED的 阿拉伯芥轉殖株,發現根系變短、ABA含量較高及提早老化、光化學消散(photochemical quenching, qP)及非光化學消散(non-photochemical quenching,NPQ)能力較差、整體carotenoid含量下降、累積較多的apocarotenoid及非生物逆境之耐受性較差。由此證明阿拉伯芥轉植株之carotenoid被大量分解,導致自我保護能力下降,而迫使植株提早進入生殖世代。 Oncidium Gower Ramsey ‘Sunkist’ (Sun) and Oncidium Gower Ramsey ‘White Jade’ (WJ), occurred naturally from an original variety of Oncidium Gower Ramsey (GR) in an orchid farm. This study was to analyze and examine the relationship of carotenoid biosynthesis and accumulation mechanisms and coloration diversities among these three cultivars, and physiological and biochemical functions of OgCCD1s and OgNCED. The HPLC analysis revealed that yellow Gower Ramsey accumulated lutein, violaxathin, 9-cis-violaxathin and neoxanthin; orange ‘Sunkist’ accumulated an additional β-carotene, and ‘White Jade’ is devoid of carotenoid compounds. ‘White Jade’ contained higher ABA and its flower senescence was accelerated. Nine expressed genes involved in carotenoid biosynthesis in mature bud period were analyzed and found that expression level of β-hydroxylase (OgHYB) and zeaxathin epoxidase (OgZEP) was displayed in yellow Gower Ramsey, relative to the down-regulation of OgHYB and OgZEP exhibited in orange Sunkist, which resulted in the accumulation of β-carotene and orange coloration in ‘Sunkist’ floral tissues. However, White Jade is caused by the up-regulation of OgCCD1 (Carotenoid Cleavage Dioxygenase 1), which catabolizes carotenoid metabolites. Transient expression of bud-specific promoter (Pchrc) driven OgCCD1 in yellow lip tissues of Gower Ramsey by bombardment confirmed its function on disintegrating carotenoid compounds. Methylation assay of OgCCD1 promoter in White Jade and Gower Ramsey revealed that hyper DNA methylation presented in OgCCD1 promoter region of Gower Ramsey, but not in that of White Jade. It suggests that OgCCD1 involved in pigmentation loss of ‘White Jade’. Five members of OgCCD1 family were cloned form flower tissue of White Jade and Gower Ramsey with Lambda phage cDNA library. Localization of OgCCD1 and OgNCED in protoplast of Arabidopsis by Confocal microscopy revealed that OgCCD1 was expressed in the chloroplast membrane and cytosol and OgNCED was expressed in the chloroplast. In addition, OgCCD1s and OgNCED T3 transgenic Arabidopsis showed shorter root length, higher ABA content, more apocarotenoid accumulation and early senescence, and poor tolerance with abiotic stress than control group. This study suggested that OgCCD1 is involved in the formation of white floral coloration flower in Oncidium Gower Ramsey ‘White Jade’ by disintegrating carotenoid compounds. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/248274 |
顯示於: | 植物科學研究所 |
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ntu-100-R97b42032-1.pdf | 23.32 kB | Adobe PDF | 檢視/開啟 |
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