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蛋氨酸是一种含硫的必需氨基酸,在人类和动物营养中占有重要地位,但很多粮食作物(如豆类)的蛋氨酸含量偏低,通过常规育种手段提高作物蛋氨酸含量的潜力有限。近年来,利用基因工程手段已成功地在许多植物中提高了蛋氨酸的含量。本文综述了通过基因工程手段提高植物蛋氨酸含量的两种途径:提高富含蛋氨酸的储藏蛋白含量和提高游离蛋氨酸的含量。文中重点介绍了蛋氨酸合成过程中的关键酶——胱硫醚γ-合成酶(CGS)的功能、胱硫醚γ-合成酶N端在维持CGS mRNA稳定性方面的作用和对其进行调控的分子机制,指出了目前通过分子育种手段提高蛋氨酸含量方面存在的问题,认为要提高豆类作物的含硫氨基酸含量,应将CGS基因和富含蛋氨酸的储藏蛋白基因同时进行转化。
Methionine is a sulfur-containing essential amino acid and plays an important role in human and animal nutrition. However, the methionine content of many food crops (such as legumes) is low, and the potential for increasing methionine content by conventional breeding is limited. In recent years, genetic engineering has succeeded in increasing methionine content in many plants. This article reviews two approaches to increasing methionine levels in plants by genetic engineering: increasing methionine-rich storage protein content and increasing free methionine content. In the paper, the function of cystathionine γ-synthase (CGS), a key enzyme in methionine synthesis, is introduced. The function of N-terminal of cystathionine γ-synthase in maintaining the stability of CGS mRNA is emphasized and regulated Molecular mechanism, and pointed out the current problems of raising methionine content by means of molecular breeding. It is suggested that CGS genes and methionine-rich storage protein genes should be transformed simultaneously to improve the sulfur-containing amino acid content in legumes.