GmCHS8和GmIFS2基因共同决定大豆中异黄酮的积累

大豆异黄酮受多基因控制，采用传统育种方法提高大豆异黄酮含量比较困难。我们之前的研究中表明，CHS8基因在异黄酮生物合成过程中发挥着重要作用，但CHS8基因过量表达并不能显著提高异黄酮含量。本研究利用Microarray技术，检测了高异黄酮品种RCAT Angra (RCAT)和低异黄酮品种Harovinton (HVNT)的18 362基因在种子发育过程中表达水平的变化以及大豆种子中异黄酮累积的趋势，利用RT-PCR证实CHS8和IFS2分别是CHSs和IFSs基因家族中的主要基因；证实CHS8是类苯基丙醇主路径中的主基因，并发现异黄酮支路中的IFS2基因在RCAT和HVNT品种中表达差异亦达到显著水平。进一步利用发根农杆菌转化系统，在大豆上分别过量表达CHS8、IFS2和CHS8+IFS2，前两者异黄酮含量较对照分别提高65.9%和34.4%，但增幅未达显著水平；而后者则提高了82.3%，增幅达显著水平(P<0.0001)，因而证实大豆中异黄酮的积累由CHS8和IFS2基因共同决定。

GmCHS8 and GmIFS2 Gene Co-Determine Accumulation of Isoflavonoid in Soybean

Soybean isoflavonoids (isoFLVs) are natural secondary compondsproduced in Phenylpropanol metabolism Pathway. In past ten years, the isoFLVs were proved with anti-cancer activity to human health and therefore intensively included in nowadays food industry. However, the low content in natural soybean germplasm is a major limit to be weed in desired population. Herein we report that expression patterns of 18 362 genes were monitored by using Microarray between 30 to 70 days after pollination (DAP) during the soybean seed development. The expression profile of CHS8 and IFS2 revealed by both Microarray and RT-PCR indicated these two genes may play critical roles in determination of the accumulation of isoFLV in soybean seeds. According to Agrobacterium rhizogenes transformation system, over-expression of individuals of CHS8 and IFS2 resulted in 65.9% and 34.4% isoFLV increase respectively, but not significant in Duncan’s multiple test at 0.05 probability level. However, co-expression of CHS8+ IFS2 significantly increased (P<0.0001) the isoFLV content up to 82.3% when comparing to non-transgenic control. Conclusively, both IFS2 and CHS8 gene co-determine the accumulation of isoFLV in soybean.