Study On Differentially Expressed Genes In Different Organs Of The Flavonoid Biosynthesis Pathway Of Ampelopsis Megalophylla

Ampelopsis megalophylla is mainly used for clinical treatment of hypertension.Early research showed that main chemical components of Ampelopsis megalophylla were flavonoids.Dihydromyricetin,myricitrin,quercitrin and myricetin,which were the main flavonoid activity components,had obvious antihypertensive effect.At the genetic level,there was no research on the plant,and the molecular mechanism of the function of blood pressure lowering had not been reported.This research studied on the transcriptome of the leaves,flowers and fruits of the plant by Illumina sequencing technology,and a great deal of gene expression information was obtained from analytical results.Based on the information,the effect factors of blood pressure lowering would be further analyzed and the related functional genes in biosynthesis of active components,which were dihydromyricetin,myricitrin,quercitrin and myricetin,would be explored.The specific research contents and results were as follows:(1)The HPLC technique was used to determine 4 main kinds of the flavonoid active components,such as dihydromyricetin,which were found in the fruits,flowers and leaves of the plant.The results showed that the constituents of components from the different organs were significantly different.The content of dihydromyricetin was almost equal in the leaves and flowers,but it was very low in the fruits.The content of myricitrin in the leaves was significantly higher than that in the flowers and fruits.The contentof quercitrin and myricetin were both relatively less in the leaves and flowers,and the two components cannot be detected in the fruits.(2)The transcriptome of the leaves,flowers and fruits were sequenced by Illumina sequencing technology.The total amount of raw data obtained by sequencing was more than 15 G,and the Q20 of all the data were more than94%,and the Q30 of all the data were more than 89%.A total of 48915 Unigenes were obtained,the length of N50 reached 1648 bp,the average length of the Unigenes were 888 bp.Most of the sequences were quite long,which showed that the results of sequencing and assembly were of good quality.Compared with several protein databases,such as Gene ontology,Pfam,eggnog,KEGG ko,TmHMM,SignalP and so on,about 67.28% of the genes had high homology with the reported genes in other plants,and the more comprehensive functional annotation information and the prediction results of protein coding regions were obtained.The analysis results of KEGG metabolic pathway showed that the differentially expressed genes between different organs existed in different metabolic pathways of flavonoids,and the differentially expressed genes,which were about the biosynthesis of dihydromyricetin,myricitrin,quercitrin and myricetin,in different organs was obtained.The 5 enzyme genes were FLS(flavonol synthase),F3’,5’H(flavonoid 3’,5’-hydroxylase),F3OM(flavonol 3-O-methyltransferase),DFR(flavanone 4-reductase)and LAR(leucoanthocyanidin reductase),respectively.(3)On the basis of the analysis of differentially expressed genes,the RT-qPCR technique was used to detect the expression level of the 5 enzyme genes between different organs at the same time.The suitable reference gene was selected in the experiment,and the accuracy of the gene expression in the transcriptome sequencing was confirmed.The correlation between gene expression quantity and the compound content in the plant were analyzedbetween different organs.The results showed that the difference of content of the four flavonoids between different organs was mainly influenced by the different expression of four kinds of enzyme gene,which were FLS,F3’,5’H,DFR and LAR.