Plant Science Division, University of Missouri, Columbia, MO, 65211, USA.
Plant Genetics Research Unit, USDA-Agricultural Research Service, Columbia, MO, 65211, USA.
Plant Sci. 2021 Jul;308:110912. doi: 10.1016/j.plantsci.2021.110912. Epub 2021 Apr 18.
Soybean is the preferred protein source for both poultry and swine feed. However, this preferred status is being challenged due to competition from alternative feed ingredients. To overcome this, it becomes necessary for breeders to develop soybean cultivars that contain higher protein and better nutritional composition. In this study, we have developed experimental soybean lines that not only contain significantly higher amounts of protein but also improved sulfur amino acid content. This objective was achieved by crossing a O-acetylserine sulfhydrylase (OASS) overexpressing transgenic soybean line with elevated levels of sulfur amino acid content (CS) with a high protein Korean soybean cultivar (Lee 5). Introgression of high protein and overexpression of OASS was monitored in the experimental lines at each successive generation (F2-F6) by measuring protein content and OASS activity. The average protein content of transgenic CS and Lee 5 seeds were 34.8 % and 44.7 %, while in the experimental soybean lines the protein content ranged from 41.3 %-47.7 %, respectively. HPLC and inductively coupled plasma-mass spectrometry analyses revealed that all the experimental lines developed in this study contained significantly higher amounts of sulfur containing amino acids and elemental sulfur in the seeds. The sulfur amino acid (cysteine + methionine) content of the experimental lines ranged from 1.1 % to 1.26 % while the parents Lee 5 and CS had 0.79 % and 1.1 %, respectively. SDS-PAGE and western blot analysis demonstrated that the accumulation of Bowman-Birk protease inhibitor and lunasin, two sulfur amino acid rich peptides, were elevated in experimental soybean lines. High-resolution 2D-gel electrophoresis and Delta2D gel analysis validated that an overall increase in the different subunits of 7S β-conglycinin and 11S glycinin were mainly responsible for the observed increase in the total amount of protein in experimental lines.
大豆是家禽和猪饲料中首选的蛋白质来源。然而，由于替代饲料成分的竞争，这种首选地位正受到挑战。为了克服这一问题，培育者有必要开发出含有更高蛋白质和更好营养成分的大豆品种。在这项研究中，我们开发了实验性大豆品系，这些品系不仅含有显著更高量的蛋白质，而且还提高了含硫氨基酸的含量。通过将一个 O-乙酰丝氨酸硫基转移酶（OASS）过表达的转基因大豆品系（CS）与一个高蛋白质的韩国大豆品种（Lee 5）进行杂交，实现了这一目标，该品系的含硫氨基酸含量较高。在每个连续的世代（F2-F6）中，通过测量蛋白质含量和 OASS 活性，监测了高蛋白和 OASS 过表达在实验品系中的导入。转基因 CS 和 Lee 5 种子的平均蛋白质含量分别为 34.8%和 44.7%，而实验性大豆品系的蛋白质含量分别为 41.3%-47.7%。HPLC 和电感耦合等离子体质谱分析表明，本研究开发的所有实验品系在种子中都含有显著更高含量的含硫氨基酸和元素硫。实验品系的含硫氨基酸（半胱氨酸+蛋氨酸）含量为 1.1%-1.26%，而亲本 Lee 5 和 CS 的含量分别为 0.79%和 1.1%。SDS-PAGE 和 Western blot 分析表明，Bowman-Birk 蛋白酶抑制剂和 lunasin 的积累，这两种富含硫氨基酸的肽，在实验性大豆品系中升高。高分辨率 2D 凝胶电泳和 Delta2D 凝胶分析证实，7S β-伴大豆球蛋白和 11S 球蛋白不同亚基的总体增加是实验品系中总蛋白量增加的主要原因。
