| Leafy sweet potato,whose tender stems and leaves are served as a vegetable,is a new kind of sweet potato.It is sought after due to its good taste and rich nutrition.In order to fully understand the genetic background of Chinese leafy sweet potato varieties,the genetic diversity of 73 Chinese leafy sweet potato varieties was analyzed by using phenotypic traits and polymorphism SNPs in the present study.Meanwhile,integrated metabolome and transcriptome approaches were used to screen bitter-and astringentrelated metabolites and genes of sweet potato tender stems and leaves.The main research results were as follows:1.Principal component analysis was performed on 73 leafy sweet potato varieties using 11 phenotypic traits.Three principal components are obtained with a 72.62%cumulative variance explanation,which could basically reflect the comprehensive information of 11 phenotypic traits.The clustering analysis result showed that 73 varieties were divided into 5 groups.The phenotypic traits of some varieties have no significant difference.2.Through whole genome resequencing of 73 leafy sweet potato varieties,a total of 231,425,809 high-quality SNPs were obtained and used for population structure and cluster analysis.Both population structure and cluster analysis could divide 73 varieties into two groups: subgroup(A)with complex genetic background,and subgroup(B)with simple genetic background.The genetic distance was between 0.000 and 0.056.The clustering result wasn’t correlated with the variety’s origin.3.A total of 426 differentially accumulated metabolites(DAMs)in 11 classes were detected by widely-targeted metabonomics between XU18(bitter variety)and EC03(CK).Among them,280 metabolites had higher accumulation in XU18,including 85 amino acids and their derivatives,77 flavonoids,46 phenolic acids,6 lipids,19 alkaloids,8 terpenoids,8 organic acids,8 lignans and coumarins,1 tannin,4 nucleotides and their derivatives,and 18 others.Amino acids and their derivatives(L-Histidine,LHomophenylalanine,Thr-Gly),phenolic acids(caffeic acid,ferulic acids,quinic acids),flavonoids(dihydromyricetin,epicatechin glucoside,catechin-4-β-Dgalactopyranoside,epicatechin-3’-O-β-D-glucopyranoside,quercetin glycosides,kaempferol glycosides)are the determinants of bitter taste of sweet potato tender stems and leaves.Based on the transcriptome,5413 differentially expressed genes(DEGs)were detected between XU18 and EC03.Among them,29 DEGs were identified,which were involved in “phenylpropanoid biosynthesis”,“flavonoid biosynthesis”,and“flavone and flavonol biosynthesis” processes.The results of gene-metabolite correlation analysis showed that the above 29 DEGs were mainly positively correlated with 28 phenolic acids and flavonoids DAMs.4.A total of 462 DAMs in 11 classes were detected by widely-targeted metabonomics between GS(astringent variety)and EC03(CK).Among them,223 metabolites had higher accumulation in XU18,including 69 amino acids and their derivatives,64 flavonoids,29 phenolic acids,5 lipids,13 alkaloids,4 terpenoids,11 organic acids,10 lignans and coumarins,1 nucleotide and its derivatives,1 tannin,16 others.Phenolic acids(caffeic acid,p-coumaric acids,shikimic acids),flavonoids(dihydromyricetin,epicatechin glucoside,catechin-4-β-D-galactopyranoside,epicatechin-3’-O-β-D-glucopyranoside,quercetin glycosides,kaempferol glycosides),and tannin(procyanidin A2)are the determinants of astringent taste of sweet potato tender stems and leaves.Based on the transcriptome,5707 differentially expressed genes(DEGs)were detected between G0722 and EC03.Among them,22 DEGs were identified,which were involved in “phenylpropanoid biosynthesis”,“flavonoid biosynthesis”,and “flavone and flavonol biosynthesis” processes.The results of genemetabolite correlation analysis showed that the above 22 DEGs were mainly positively correlated with 33 phenolic acids and flavonoids DAMs. |
