基因改造香蕉的研發現況

Current Developments in Genetically Modified Bananas

基因改造科技對於作物產量提升、成本降低以及縮短育種時間上具有顯著的效益，惟基改作物在食品與生態安全方面仍面臨許多爭議。目前基因改造科技在植物生理、生化與基因功能驗證等基礎研究方面，已成為不可或缺的一個環節。香蕉是熱帶地區重要的經濟產業，三倍體香蕉新品種之育成，常因無子、雄不稔及生育力退化等因素，使雜交育種難以進行，或需要耗費更多的時間，基因改造技術對香蕉品種改進不失為一快速而有效的方式。在‘Lady Finger　’香蕉品種中穩定表現抑制細胞凋亡相關基因，包括Bcl-x_L，Ced-9或Bcl-2 3'UTR，轉殖株抗黃葉病能力可達5個月以上。利用RNA干擾技術降低ACC合成酶或ACC氧化酶的表現，對香蕉果實後熟過程之調控有顯著影響，與未轉殖的對照組相比較，Mh-ACO2默化轉殖株於果實後熟時期，具有降低乙烯生成，減少呼吸速率以及延緩果皮轉色等現象。利用基因轉殖技術開發提升營養價值的香蕉，以解決營養缺乏問題，轉殖鐵蛋白的香蕉可提升鐵離子含量達6.32倍，並增加鋅離子含量達4.58倍。基因改造香蕉生產口服疫苗已廣受注目，將表現GP5重組蛋白的基改香蕉餵食豬隻，可誘發免疫反應有效抵抗豬生殖與呼吸道綜合症病毒。 Genetically modified (GM) techniques have made important contributions to increasing global crops production, lowering farm-level production costs, and shortening crop breeding progressions. However, the role of GM crops for food security and environmental impacts is still the subject of public controversy. GM technology is essential to basic plant science, such as plant physiology, biochemistry, and validation of gene function. Banana industry is important in tropical area. Triploid banana breeding is rather difficult and time consuming due to seedless, male-sterility, and highly reduced female fertility. GM techniques can serve as an alternative way for banana improvement. The constitutive expression of apoptosis-inhibition-related genes, including ”Bcl-x_L”, ”Ced-9”, or ”Bcl-2” 3'UTR, in transgenic banana 'Lady Finger' showed high levels of resistance to ”Fusarium” wilt for at least 5 months. Downregulated ACC synthase or ACC oxidase by using RNA-interference strategy could change banana fruit ripening process significantly. When compared with the non-transgenic counterpart, the Mh-ACO2 silenced transgenic banana fruit exhibited reduced ethylene production, decreased respiration rate, and delayed the change of peel color in the ripening stage. Biofortified transgenic banana provided an effective means of controlling the iron deficiency. A 6.32-fold increase in iron accumulation and a 4.58-fold increase in the zinc levels were showed in transgenic banana expressing ferritin constitutively. The use of transgenic banana for oral vaccine production has attracted worldwide attention. Pigs orally immunized with transgenic banana showed a specific anti-GP5 response for against porcine reproductive and respiratory syndrome virus.