Study On Anthocyanin Pathway Of Tea Tree Flower Based On Metabolome And Transcriptome

According to the current study,the petals of the camellia tea tree(named as tea tree flowers)are white in color,and a few are pink.In this paper,tea tree flowers of Baitang,Huizhou(purple buds,petal pink)and the flowers of Zijuan tea tree(purple bud,petal white)were taken as the main research object.The transcriptome and metabolome analysis were used to explore the anthocyanins pathway mechanism of tea tree flowers,especially the mechanism that causes the color of the two tea tree flower petals to be different.At the same time,tea tree flower is renewable resource,and it is rich in yield.It has the characteristics of ―long flowering period,large amount of flowers,less fruiting and short life span‖.At present,the utilization rate is extremely low.Through the research on the regulation mechanism of anthocyanin pathway in the tea tree flowers,it may provide theoretical guidance for reforming the color of tea tree flowers and increases the ornamental value of tea gardens.The results of the study are as follows: 1.Through the same stage of pink tea tree flower BTP and white tea tree flower ZJW metabolome(ZJW1vs BTP1,ZJW2 vs BTP2,ZJW3 vs BTP3,ZJW4 vs BTP4,ZJW5 vs BTP5)analysis showed that the content of catechin and its derivatives was white flowers slightly more than pink tea tree flowers,during the flowering process of tea tree flower.white tea tree flowers are significantly more than pink tea tree flowers among Epigallocatechin.Pink tea tree flower has more anthocyanin content than white tea tree flower,such as,cyanidin-O-syringic acid,cyanidin-3-O-glucoside and petunidin-3-O-glucoside and Cam266 geranium-3-O-glucoside pigment,which is clearly the reason for the difference in the color of the two tea tree flowers.2.During the flowering,the metabolic group of pink tea tree flowers(BTP1vs BTP3,BTP2 vs BTP3,BTP2 vs BTP4,BTP3 vs BTP4,BTP3 vs BTP5,BTP4 vs BTP5)was analyzed.Situation of metabolite associated with the anthocyanin pathway are: The content of catechins and derivatives,anthocyanins,quercetin and kaempferol,eriodictyol,naringenin and naringin are basically neither up-regulated nor down-regulated.Dihydromyricetin slowly decreased in the flowering process of pink tea tree flowers.In summary,the content of metabolites associated with the anthocyanin biosynthetic pathway remained generally stable.3.During the flowering,the metabolic group of white tea tree flowers was analyzed(ZJW1v ZJWP3,ZJW2 vs ZJW3,ZJW2 vs ZJW4,ZJW3 vs ZJW4,ZJW3 vs ZJW5,ZJW4 vs ZJW5).The situation of metabolite associated with the anthocyanin pathway are: the overall metabolite content associated with the anthocyanin biosynthetic pathway is generally decreasing.The content of flavanones decreased slowly,and the content of most catechins and derivatives decreased.The content of anthocyanins and flavonols remained basically stable.4.During the flowering,by analyzing the transcriptome of pink tea tree flowers(BTP1vs BTP3,BTP2 vs BTP3,BTP2 vs BTP4,BTP3 vs BTP4,BTP3 vs BTP5,BTP4 vs BTP5),it was found that: The gene that promotes the synthesis of anthocyanin metabolites,except for the DFR(CSA003949)gene is down-regulated,most of the genes are neither up-regulated nor down-regulated before the 3-stage,and up-regulated after the 3-stage.In addition to the down-regulation of the LAR gene(CSA018523),most of the genes that inhibit the synthesis of anthocyanin metabolites remained stable and a small up-regulation trend.Down-regulation of the LAR gene is also one of the reasons why "+"-catechins are less than "-"-catechins.5.During the flowering,by analyzing the transcriptome of white tea tree flowers(ZJW1v ZJWP3,ZJW2 vs ZJW3,ZJW2 vs ZJW4,ZJW3 vs ZJW4,ZJW3 vs ZJW5,ZJW4 vs ZJW5),it was found that: Genes that promote the synthesis of anthocyanin metabolites,except for CHI(CSA023536),CHS(CSA031662),and DFR(CSA003949,CNG 45659)genes down-regulated,and other genes are down-regulated before stage 2,and 3 to 4 stages are significantly up-regulated.In other stages,gene expression maintained a stable level with the previous stage.Among the genes that inhibit the synthesis of anthocyanin metabolites,most of them were down-regulated or maintained stable except for the LAR gene(CSA018523,CSA01986).6.Combined with metabolome and transcriptome analysis,it is concluded that the expression level of ANR gene is similar in the two tea tree flowers.The regulation of ANR gene is not the reason for the difference in color of two tea tree flowers.ANR gene has higher expression level than UGT75C1 gene.Therefore,the content of catechins and their derivatives is more than that of anthocyanins.The difference in the regulation of DFR gene is the main reason for the difference in color of two tea tree flowers: CSA0035727 in DFR gene corresponds to the synthesis of pelargonidin,CNG45659 and CNG38209 correspond to the synthesis of cyanidin Cyanidin,and CNG7970 and CSA003949 correspond to delphinidin(Delphinidin).The difference in DFR gene regulation makes the anthocyanin biosynthesis pathway in the white tea tree flower more concentrated in the delphinidin synthesis branch,while in the red tea tree flower,it concentrates on the two branches of cornflower pigment and delphinidin pigment.(Slightly enriched in the cornflower pigment branch),so that the pink tea tree flower contains more cyanidin than the white tea tree flower,which eventually causes the "Zijuan" tea tree flower ZJW to appear white,Huizhou Baitang local group Tea tree flower BTP is pink.This is why white tea tree flowers contain more epigallocatechin than pink tea tree flowers.In addition,the CSA018076 and CSA028872 genes in the UGT75C1 gene also differed from the color of the two tea tree flowers because the two genes were slightly differentially expressed in the two tea tree flowers,which enhanced the results of DFR gene regulation.7.In general,the gene regulation of the anthocyanin synthesis pathway is similar in the flowering process of two tea tree flowers,but the pink tea tree flower has almost the higher gene expression level than the white tea tree flower.Most of the metabolites associated with anthocyanin synthesis,pink tea tree flowers more than white tea tree flowers,but white tea tree flowers have more Epigallocatechin and dihydromyricetin than pink tea tree flowers.Although the total amount of catechins and their derivatives in pink tea tree flowers is relatively small compared with white tea tree flowers,catechin and anthocyanins are more abundant and have greater ornamental value.