Studies On The Temporospatial Expression Of Soybean PAL Gene Family And PAL2-1 Gene Regulation Of Content Isoflavones

Soybean isoflavone is the secondary metabolites formed in the process of soybean growth,which is the generic terms of a class of polyphenol compounds contained multiple phenolic hydroxyl in soybean and its products.Soybean isoflavones has many beneficial effect on humans. Meanwhile,soybean isoflavone has very important function on plant disease resistance,insect resistance and root nodules.whereas,the content of isoflavones in soybean seeds is low. With the gradually deepening understand on soybean isoflavones beneficial functions,the demand of soybean isoflavones for people reached new heights. Therefore,that understanding the growth accumulation process of isoflavones in soybean seed is of great significance to improve the content of isoflavones.Isoflavone biosynthesis pathway is a branch of phenylalanine metabolic pathways,phenylalanine ammonia-lyase is the entry point enzyme of phenylalanine metabolic pathways, and it is the key enzyme and rate-limiting enzyme.PAL genes PAL genes play an important role in nodule formation, cell differentiation,pigementation and other physiological metabolisms.The study found that the relative expression of PAL gene obviously increase or decrease in coordination with the soybean isoflavones content. The expression features,ontrol mode and regulation mreechanism in the process of synthesis and accumulation of soybean isoflavones was researched,which results provided theoretical basis for improving soybean isoflavone content at the gene level.This research started with each member of PAL gene family.For gene sequence of eight member(PAL1-1,PAL1-2,PAL1-3,PAL2-1,PAL2-2,PAL2-3,PAL2-4and PAL3gene),The expression of each gene family member in the root and other parts was analyzed during Ve to R8 growth period, which was used the Real- time PCR method.It is cleared that what were the expression characteristics of each member of PAL gene family in time and space. Because the PAL2-1 gene which was a member of PAL2 subfamily gene in the differen t parts significantly expressed, it was knocked out or overexpressed by transgenosis.Then the isoflavone content of transgenic plants was determined, and the influence of PAL2-1 gene on the soybean isoflavone content was analyzed.The main results were as follows:(1)The general relative expression of PAL gene family in generative growth periods is higher than that in vegetative growth period s, which is higher in leaf and grain than others.(2)The relative expression of PAL1-1,PAL2-1 and PAL2-3 genes in each place is significantly higher than other kin genes.Differing in the stable expression of PAL1-1gene in each period, the relative expression peak of PAL2-1 gene and PAL2-3 gene successively appear in the later stage of generative growth period.(3)The plant expression vector of p CAMBIA3301-Gm PAL2-1 and the plant RNAi interfere vector were built,which were imported into the plants of “Northeast Agricultural 50”.Their plants of T1 generation were analysised by the Real-time PCR.The result shows that the relative expression of PAL2-1 gene in positive plants of overexpression was higher than that in common soybean variety.The result shows that the relative expression of PAL2-1 gene in positive plants of interference was inferior to that in common soybean variety.(4)Through the soybean genetic transformation experiment,it confirmed that the content of isoflavones and three aglycones was improved by overexpressing PAL2-1 gene.The increase of glycitein was significant while the increas e of genistein was least.(5)Suppressing the expression of PAL2-1 gene in soybeans could significantly reduce the content of isoflavones,daidzein and genistein,and increase the content of glycitein.