Evaluation of amino acid content and nutritional quality of transgenic soybean seeds with high-level tryptophan accumulation
Evaluation of amino acid content and nutritional quality of transgenic soybean seeds with high-level tryptophan accumulation
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DOI：
10.1007/s11032-009-9334-3
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发表时间：
2010-02-01
影响因子：
3.1
通讯作者：
Wakasa, Kyo
中科院分区：
文献类型：
--
作者：
Ishimoto, Masao;Rahman, Shaikh M.;Wakasa, Kyo
邻氨基苯甲酸合成酶（AS）是色氨酸（Trp）生物合成的关键调控酶，受Trp的反馈抑制。将编码水稻AS抗反馈突变α亚基（OASA 1D）的基因导入大豆[Glycine max（L.）[梅里尔]通过粒子轰击。总共开发了7个不同的转基因品系，其显示出在其种子中游离色氨酸的积累显著增加。游离色氨酸的过量生产在后代中稳定遗传，对植物生长或繁殖没有任何明显的不利影响。转基因种子的总色氨酸含量也约为非转基因种子的两倍，而蛋白结合色氨酸的量基本上不受OASA 1D表达的影响。尽管游离色氨酸含量显著增加，但通过高效液相色谱法结合质谱法进行的代谢分析显示，转基因种子中其他芳香族化合物的含量变化不大。本研究以人工养殖虹鳟鱼为实验材料，建立了一套快速、可行的转基因大豆种子营养品质评价体系。添加OASA 1D转基因大豆种子或非转基因种子加晶体色氨酸的鱼饲料增加了养殖鱼的生长速度。这些结果表明，用OASA 1D转化是改善用于人类和动物食品的大豆（或其它谷类豆类）的营养品质的可靠方法。
Anthranilate synthase (AS) is a key regulatory enzyme in tryptophan (Trp) biosynthesis and is subject to feedback inhibition by Trp. The gene encoding a mutated feedback-resistant alpha subunit of rice AS (OASA1D) under the control of either a soybean glycinin gene promoter or the 35S promoter of cauliflower mosaic virus for seed-specific or constitutive expression, respectively, was introduced into soybean [Glycine max (L.) Merrill] by particle bombardment. A total of seven different transgenic lines that showed markedly increased accumulation of free Trp in their seeds were developed. The overproduction of free Trp was stably inherited in subsequent generations without any apparent detrimental effect on plant growth or reproduction. The total Trp content of transgenic seeds was also about twice that of nontransgenic seeds, whereas the amount of protein-bound Trp was not substantially affected by OASA1D expression. In spite of the marked increase in free Trp content, metabolic profiling by high-performance liquid chromatography coupled with mass spectrometry revealed little change in the amounts of other aromatic compounds in the transgenic seeds. We developed a rapid and feasible system based on farmed rainbow trout to evaluate the nutritional quality of a limited quantity of transgenic soybean seeds. Supplementation of fish food with OASA1D transgenic soybean seeds or with nontransgenic seeds plus crystalline Trp increased the growth rate of the farmed fish. These results indicate transformation with OASA1D is a reliable approach to improve the nutritional quality of soybean (or of other grain legumes) for human and animal food.