Metabolomic and Transcriptomic Analyses of Anthocyanin Biosynthesis Mechanisms in the Color Mutant Ziziphus jujuba cv. Tailihong

Abstract

The purplish-red color of “Tailihong” jujube fruit skins is caused primarily by anthocyanin accumulation, but the mechanisms that underlie anthocyanin biosynthesis in jujube fruit have rarely been studied. We performed metabolomic and transcriptomic analyses of jujube fruit skins at different developmental stages and identified a total of 158 flavonoids, among which cyanidin-3-O-rutinoside and peonidin-3,5-O-diglucoside were the primary anthocyanins. During fruit development and maturation, the anthocyanin content was strongly correlated with the expression of ZjANS and ZjUGT79B1, suggesting that these are key genes in the anthocyanin biosynthesis process. Transcriptomic analysis indicated that the transcription factors ZjMYB5, ZjTT8, and ZjWDR3 regulated anthocyanin biosynthesis in jujube fruit skins. Subcellular localization experiments confirmed that ZjANS and ZjUGT79B1 were localized to the nucleus and the endoplasmic reticulum. ZjMYB5 and ZjTT8 were found only in the nucleus, whereas strong fluorescence signals from ZjWDR3 were observed in the nucleus and cytoplasm. Prokaryotic expression and in vitro enzyme activity assays showed that the recombinant ZjANS protein catalyzed the formation of cyanidin from (+)-catechin. Secondary glycosylation by ZjUFGT79B1 modified cyanidin-3-O-glucoside to produce cyanidin-3-O-rutinoside, and ZjCCoAOMT readily catalyzed the production of the methylated anthocyanin peonidin-3,5-O-diglucoside from cyanidin 3,5-O-glucoside. Dual-Luciferase and GUS activity assays showed that the ZjANS and ZjUGT79B1 promoters were activated by ZjMYB5, ZjTT8, and ZjWDR3. All data indicated that these three transcription factors played important roles in anthocyanin biosynthesis in the color mutant Ziziphus jujuba cv. Tailihong, contributing to anthocyanin accumulation by enhancing the expression of ZjANS and ZjUGT79B1.

Exploring the genic resources underlying metabolites through mGWAS and mQTL in wheat: From large-scale gene identification and pathway elucidation to crop improvement

“…These mutants were named transparent testa ( tt ), and the responsible mutated genes ( TT genes) were demonstrated to encode candidates in the flavonoid/anthocyanin pathways ( Lepiniec et al., 2006 ). The indication that flavonoids/anthocyanins are one major class of plant chromogenic compounds is probably why researchers tended to conduct targeted metabolomics measurements covering the flavonoids and/or anthocyanins in plant-color-related cases ( Shi et al., 2020b ; Jiao et al., 2020 ; Qiu et al., 2020 ). Subsequently, differential metabolites and corresponding responsible candidate genes were collected to explain the molecular mechanisms of color variation at the metabolomic and, probably, the transcriptomic levels ( Li et al., 2020 ; Zhan et al., 2020 ).…”

Comprehensive Transcriptome–Metabolome Analysis and Evaluation of the Dark_Pur Gene from Brassica juncea that Controls the Differential Regulation of Anthocyanins in Brassica rapa

“…Second, early biosynthetic genes (EBGs), including CHS (chalcone synthase), CHI (chalcone isomerase), F3H (flavanone 3-hydroxylase), F3′H (flavanone 3’-hydroxylase), and FLS (flavonol synthase) provide precursor substrates for the synthesis of flavonols and anthocyanins. The late biosynthetic genes (LBGs), including DFR (dihydroflavonol 4-reductase), ANS (anthocyanin synthase), and UGT (UDP-glucosyltransferase), are essential for producing anthocyanins and certain flavonoids [ 8 , 9 , 10 , 11 , 12 , 13 ]. Some studies show that LBGs are regulated by the MBW complex, which consists of MYB, bHLH, and WD40 transcription factors, and EBGs are usually activated by the R2R3-MYB transcription factor [ 14 , 15 ].…”

Integrated metabolomic and transcriptomic analysis of the anthocyanin regulatory networks in red walnut

“…In recent years, the combination analysis of transcriptome and metabolome has widely used to clarify anthocyanin biosynthesis and accumulation in plants [25][26][27][28][29][30][31]. In the current study, the regulatory networks of anthocyanin biosynthesis in walnut were conducted using two 'RW-1' natural hybrid accessions, with red and green leaves respectively.…”