植物转化中的安全标记基因

The Safe Marker Genes Used in Plant Transformation

转基因植物中的除草剂或抗生素抗性标记基因的生态环境和食用安全性一直颇有争议 .糖类分解代谢酶基因作为安全标记基因 ,近年来在植物转化中显示了巨大应用潜力 .这类标记基因编码产物是筛选剂糖类的分解代谢酶 ,使转化细胞能利用筛选剂糖类作为主要碳源从而获得优势生长 ,非转化细胞则因饥饿生长被抑制但不被杀死 ,故称为正筛选系统 (positiveselectionsystem) .目前木糖异构酶基因 (xyloseisomerase,xylA)和磷酸甘露糖异构酶基因 (phosphomannoseisomerase,pmi)等安全标记基因已成功应用于植物转化 .

Concerns have been raised that the presence of selectable marker genes such as antibiotic or herbicide resistant genes might be unpredictable hazard to the ecosystem as well as to human health. The genes coding enzymes that catalyze special sugars have showed big practical potency in plant transformation as safe marker genes. This kind of sugar catabolic maker genes can give plant cells the ability to use selective agent sugars such as xylose or mannose, therefore the transformed cells could get sufficient energy and grow dominantly while the untransformed cells are starved and inhibited from growing but not be killed. It is called positive selection system. Now the safe marker genes such as xylA (xylose isomerase gene) and pmi (phosphomannose isomerase gene) have been successfully used in plant transformation.