ACC合成酶基因之選殖及其在果樹育種上之應用

Abstract

植物荷爾蒙乙烯對植物之影響，自種子發芽以及生長、發育與老化，無不息息相關。對於更年性水果而言，乙烯在誘發果實成熟及後熟過程中，更扮演著極決定性的角色。目前已知在乙烯的生合成路徑中，其速率限制步驟（rate-limiting step）為SAM至ACC之轉換，此反應係由ACC合成酶來催化。理論上，若能控制此反應，即能調節乙烯之產生及控制果實之成熟。因此，如何利用轉殖DNA技術，來調節此關鍵反應之產物ACC，在農業上將有甚大的經濟效益。本文綜述最近利用夏南瓜（zucchini）為模式植物，選殖ACC合成酶的cDNA及其基因之最近發展。並討論利用基因轉殖技術，改變果樹的遺傳組成分，進而達到控制果實後熟之途徑。 It has been recognized that ethylene plays a crucial role in the initiation and development of ripening in climacteric fruits. Moreover, the ACC synthase is the key regulatory enzyme in the biosynthetic pathway of ethylene. It is therefore important to understand how the expression of ACC synthase gene is regulated during fruit ripening. The cloning of its gene will open new horizons of investigation on the molecular mehanism of induction of the ACC synthase activity during fruit ripening. Furthermore, it is of great agronomical interest to be able to control the fruit ripening and to delay overripening for the climacteric fruits. This article reviews the recent progress on the cloning of ACC synthase mRNA and the aprlication of antisense RNA technology to inhibit fruit ripening. The new development raises the prospect that fruit spoilage can be prevented.