大豆籽粒异黄酮含量与IFS1基因相对表达量的关系

Relationship between the Contents of Soybean Isoflavone and the Relative Expression Quantity of IFS1 Gene in Soybean

异黄酮合酶基因(isoflavone synthase,IFS)是合成异黄酮的关键酶基因之一,能够在转录水平对异黄酮的生物合成进行调控。为研究大豆籽粒中IFS基因与大豆异黄酮合成的关系,本研究选择8个不同地理来源的大豆品种,利用高效液相色谱法(HPLC)测定大豆籽粒中异黄酮4种主要组分含量(染料木素,大豆甙元,染料木甙和大豆甙),并利用荧光定量PCR的方法测定了IFS1基因(IFS基因的同源基因之一)在大豆籽粒中的相对表达量。结果表明:大豆异黄酮4种主要组分含量在不同品种中差异较大,在所测试的品种中,中品03-5368和中豆27籽粒的总异黄酮含量较高,分别达到1 873.136μg/g、1 526.203μg/g,兴县灰皮支和Wiliams82总异黄酮含量较低,分别为1 258.591μg/g和1 255.300μg/g;大豆籽粒中大豆异黄酮总含量与籽粒中IFS1基因的相对表达量呈显著正相关(r=0.995 5,P<0.000 1),大豆异黄酮4种主要成分中的染料木素和大豆甙与IFS1基因的相对表达量也成正相关,这一结果说明IFS1基因作为苯丙氨酸合成路径中进入异黄酮合成途径的第一个酶,在异黄酮化合物合成中起关键作用。本研究不仅可以为明确大豆异黄酮合成途径中IFS基因分子调控机理提供科学理论依据,而且能够为高异黄酮生物合成和大豆品质改良奠定理论基础。

Isoflavone synthase （IFS） is one of the key enzymes involved in the synthesis of isoflavones, which participate in the regulation of isoflavone biosynthesis at the transcriptional level. In order to reveal the relat- ionship between the isoflavone content in soybean seed and the expression level of IFS1 gene, eight soybean varieties, coming from different geographical origin, were selected to carry out the following experiments. The expression of IFS1 was quantified by fluorescence quantitative PCR and the isoflavones components of four main content （Genistein, Daidzein, Genistin and Daidzin） were measured by high performance liquid chromatography （HPLC）. The four main components of the isoflavones varied among different soybean varieties. Total isoflavone contents in Zhongpin03-5368 and Zhongdou27 was 1 873.136 μg/g and 1 526.203 μg/g, respectively. While the contents were as lower as 1 258.591 μg/g and 1 255.300 μg/g in Xingxian Huipizhi and Wiliams82, respectively. There was a significant positive correlation between the total contents of isoflavone （r=0.995 5, P〈0.000 1）, genistein, daidzin and the relative expression quantity of IFS1 gene. It could be induced that IFS gene, as the first enzyme participating into isoflavones compounds synthesized, might play a key role in phenylalanine synthesis pathway. Our results will be helpful for better understanding the regulation mechanism of IFS gene. It will also provide more information on isoflavone biosynthesis and quality improvement of soybean.