中文摘要：

荫蔽导致植物所受红光/远红光（ R/f r ）比值下降,为探究荫蔽对大豆幼苗异黄酮合成的影响,本试验 以耐荫性差异显著的大豆品种“ ND1 2”和“ C103 ”幼苗为研究材料,分别施以不同比例红光/远红光（ R/FR）处 理,对其叶片、下胚轴、根系中异黄酮积累量及关键酶基因表达情况进行比较研究.结果表明,低 R/FR条件下, 强耐荫品种“ ND12”叶片中总异黄酮及染料木素G E的含量极显著上升,下胚轴中极显著下降,弱耐荫品种 “ C103”则相反.同时,低 R/FR使强耐荫品种“ ND12”叶片中异黄酮合成关键基因/ fS 2、4C i、 C4//和 C f f l的表 达量极显著上调,其变化趋势与异黄酮积累变化规律-致,而弱耐荫性品种“ C103 ”则存在较大差异.荫蔽信号 诱导耐荫型大豆品种异黄酮合成,并在受胁迫部位叶片中大量积累.本研究初步揭示了荫蔽信号（低 R/FR）对 苗期大豆异黄酮的调控规律,为研究大豆异黄酮响应荫蔽信号的调控机理奠定了基础.

英文摘要：

The reduction in the ratio of red light （R） to far-red light （FR ） is an important signal of shade stress. In the present study,an experiment was conducted to study the effect of normal and low R/FR irradiation on the isoflavone con-tents of two soybean varieties ： high shade-tolerance species ‘ ND12’ and low shade-tolerance species ‘ C103 Relative expression levels of key genes, which encoded isoflavone synthetic enzymes in leaves, hypocotyls and roots were also studied. The results indicated that compared with seedlings under normal light, low R/FR increased total contents of isoflavone and genistein significantly in the leaves of 4 ND12, ,but decreased in hypocotyls ; while the opposite result was obtained in 4 C103 , . Expression of isoflavone synthesis key genes, including IFS2,4CL, C4H and CHI correlated with isoflavone accumulation under low R/FR irradiation. Shading signal induced isoflavone accumulation particularly in leave of shade-tolerance varieties,. This study preliminary clarified the shading signal （ low R/FR） that how to control the rules of isoflavone accumulation in soybean seedlings. This study laid a foundation to research regulation mechanism of soybean isoflavone response to shading signal.