基因工程改良作物种子蛋白营养品质的策略及其研究进展

作物种子蛋白是人类和牲畜日常蛋白质的主要来源;与肉类相比,植物蛋白质的营养品质往往不够完全,主要表现在禾谷类作物种子蛋白质中的赖氨酸和色氨酸含量低,而豆类和蔬菜类蛋白质缺乏蛋氨酸和半胱氨基酸等含硫氨基酸.采用传统育种技术提高作物蛋白质营养品质方面的成效不大,现代分子生物技术的进展为改良植物种子蛋白质营养品质提供了有效的技术路线,目前已发展了几种在分子水平上改良作物蛋白质营养价值的方法,包括内源蛋白质序列的修饰、同源优质蛋白基因的过量表达、异源优质蛋白基因的转移和表达、人工合成新蛋白基因、以及增加游离的必需氨基酸的含量等.本文重点从上述5个方面综述近年来采用基因工程技术提高作物蛋白质营养品质的进展,并就其中可能存在的问题作了讨论.

The Strategied and Progress of Genetic Engineering to Improve the Nutritional Quality of Crop Seed Proteins

Crop seed proteins are the major primary source of dietary protein consumed by humans and animals, improving their quality will make a significant contributions to meet our future food needs. But, plant proteins are generally incomplete in nutrition due to their deficiency in several essential amino acids, such as, lysine and tryptophan in cereals and methionine and cysteine in legumes. Attempts to develop crops with enhanced compositions of lysine and methionine have been less than satisfactory. Modem biotechnology offers alternative approaches for rectifying this nutrition deficiency. In the past decade, several transgenic strategies aimed at modifying the amino acid composition of plant proteins for nutrition improvement had been developed and tested, which included synthetic proteins, modification of protein sequences, over-expression of heterologous or homologous proteins, and metabolic engineering of the free essential amino acid pool and protein sink. The progress and potential of these approaches and studies mentioned above were reviewed in this paper.