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Development of Transgenic Papaya Conferring Double-Resistance to Two Viruses
|作者:||葉錫東||關鍵字:||技術發展;transgenic papaya;園藝, 生物技術, 植物保護類;轉基因木瓜;雙重抗性;木瓜輪點病毒;木瓜畸葉嵌紋病毒;體胚;double-resistance;Papaya ringspot virus;Papaya leaf- distortion mosaic virus;somatic embryos||摘要:||
木瓜輪點病毒 (Papaya ringspot virus, PRSV) 肆虐台灣木瓜栽培區，造成嚴重損失。在過去幾年，本實驗室開發的PRSV鞘蛋白基因轉殖木瓜於溫室及農試所四年隔離田間試驗中，證實對PRSV具有良好的抗性。當進行隔離田間試驗時，發現有一新的病毒能感染轉基因木瓜，並造成嚴重病徵，經實驗證實為木瓜畸葉嵌紋病毒及木瓜畸葉嵌紋病毒 (Papaya leaf-distortion mosaic virus, PLDMV)。為能有效控制PRSV及PLDMV兩病毒，本實驗室已將PRSV及PLDMV部分CP基因以非轉譯性的策略構築在同一載體上，再利用農桿菌為媒介(Agrobacterum- mediated) 將此基因轉入泰國品種木瓜中。共得到38個R0株系具有對PRSV及PLDMV雙重抗病毒能力，此外，R0株系與日陞品種木瓜雜交後，也得到具雙重抗性之R1子代。然而，所有R0的轉殖木瓜在種植於溫室六個月待其開花後皆為母株，因此必須花費很長的育種時間，以育種方式培育出具有商業推廣的台農二號雜交品系兩性株木瓜。為了縮短轉基因木瓜性別固定育種的時間，必須建立新的木瓜轉殖方法，本實驗主要是以優良性狀的台農二號兩性株之不定根所誘導的體胚取代先前未知性狀的未成熟胚當作轉殖材料，以農桿菌作為轉殖媒介發展新的木瓜體胚轉殖方式，此方法可以快速產生具商品價值的台二木瓜，並可作為日後各種品種木瓜基因轉殖之平台。
Papaya production in Taiwan has been limited by a serious disease caused by Papaya ringspot virus (PRSV). In the past few years, our laboratory has generated the transgenic papaya lines that carry the coat protein (CP) gene of PRSV and confer resistance to the PRSV infection as confirmed by greenhouse evaluation and 4 years isolated field trials. However, PLDMV has been found capable of breaking down the resistance in PRSV CP transgenic papaya under greenhouse and field conditions. For the effective control of PRSV and PLDMV, an untranslatable chimeric construct containing truncated PRSV YK CP and PLDMV DL CP genes was transferred into papaya (Carica papaya cv. Thailand) via Agrobacterum-mediated transformation. A total of 38 lines (R0) were resistant to both PRSV and PLDMV under greenhouse conditions. Furthermore, the R1 progenies (Tainung No. 2) resistant to PLDMV DL and PRSV YK were obtained by crossing the transgenic lines with cv. Sunrise. However, all resistance transgenic lines (R0) showed female sex during flowering after six months culturing under greenhouse conditions. Thus, in order to shorten the time to fix the sex and the horticultural properties of transgenic papaya for breeding, new transformation method has to be developed in the future. In this investigation, the somatic embryos derived from the adventitious roots of in vitro multishoots of papaya with hermaphroditic sex and good horticultural properties such as individual plants of C. papaya L. cv Tainung No.2 will be used as explants to replace the embryos derived from premature seeds of unknown sex. An optimal protocol for Agrobacterium- mediated transformation via somatic embryos derived from root explants of Tainung No.2 will be developed in this investigation. Through this new approach, a commercially valuable Tainung No. 2 papaya hybrid will be generated in a short time. Also, the new approach will become a fast and efficient Agrobacterium-mediated transformation method for any papaya varieties.
|Appears in Collections:||研究計畫報告|
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