The Flavonoid Components And Transcriptome Analysis Of Magnolia Biondii

Magnolia biondii,is a kind of deciduous trees,widely used in urban greening.The typical flower color of M.biondii is pink normally.However,a red-purple flower style,named M.biondii var.purpurascens,has been found in nature.This mutant is an excellent source to study the molecular mechanism of color variation.In order to study the difference mechanism of the formation of M.biondii,two colors M.biondii species were selected as experimental material.We used HPLC-DAD/ESI-MS~2 to test the composition of the flavonoids.At the same time,using RNA-Seq and qRT-PCR,the transcriptomes of petals were obtained,the reference genes were selected,and the expression patterns of flavonoids synthesis related genes were analyzed.The study provides a theoretical basis for the genetic regulation of color-forming in M.biondii,which lays a foundation for further research into flower color improvement.The main results are as follows:1.Four types of anthocyanins,including cyanidin and peonidin derivatives,as well as ten types of flavonols,including isorhamnetin,quercetin and kaempferol derivatives that have been detected.Peonidin was the major color substances in the petals.TA and TF in M.biondii var.purpurascens petals were higher than white species.and the main flavonoids synthesis completed before revealing color blossom.2.A total of 35692 unigenes were obtained by transcriptome,and 3922 DEGs were obtained by comparing the expression of genes in each stage.13 structural genes and 3regulatory genes related to flavonoids synthesis pathway were screened out.3.The stability of every expression level of the 10 candidate reference genes in the petal were measured,wherein the genes were selected from M.biondii transcriptome database.The results showed that the most stable candidate reference genes were MbTEF.4.Among the 13 flavonoids synthesis pathway structural genes,the expression patterns of MbFLS and MbANS were most consistent with those of flavonoids and anthocyanins.The expression of most structural genes in M.biondii var.purpurascens was higher than that of M.biondii,and the change trend of gene expression in the process of flowering is consistent with the change trend of flavonoids content.It is speculated that the increase of gene expression in related structures in the synthesis pathway of flavonoids is the main reason leading to the accumulation of anthocyanins in the petals of M.biondii var.purpurascens.