Abstract
Michelia maudiae Dunn is one of the important ornamental plants in the Magnoliaceae family, and the color of its flowers usually appears naturally pure white. The discovery of a rubellis flower named M. maudiae Dunn var. rubicunda provides an opportunity to reveal the metabolism of the flavonoids and anthocyanins of this “early angiosperm” plant. Combined metabolome and transcriptome analyses were applied using white and rubellis mutant tepals. Seven stages have been divided for flower development, and forty-eight differentially altered metabolites were identified between white and rubellis tepals at a later stage. The major anthocyanins including peonidin O-hexoside, cyanidin O-syringic acid, cyanidin 3,5-O-diglucoside, cyanidin 3-O-glucoside, and pelargonidin 3-O-glucoside were upregulated over 157-fold in the mutant. Conversely, the highly significant accumulation of the colorless procyanidin or the slightly yellow epicatechin and catechin was found in white flowers. Putative homologues of color-related genes involved in the phenylpropanoid and flavonoid biosynthesis pathway were identified in the transcriptome. The increasing expression of dihydroflavonol 4-reductase (DFR) might play an important role in the occurrence of rubellis pigments, while the overexpression of anthocyanidin reductase (ANR) in white flowers may promote the biosynthesis of proanthocyanidins. Additionally, several coloration-related repressor R2R3-MYB transcription factors showed different expression levels in the tepals of the rubellis mutant. This study provides a comprehensive analysis relating color compounds to gene expression profiles of the Magnoliids plant M. maudiae. The newly generated information will provide a profound effect on horticultural applications of Magnoliaceae.
Highlights
Flower coloration is one of the most attractive characteristics and quality traits of ornamental plants and has the ability to attract pollinators and seed distributors
The primary shade of a flower color is mainly determined by the ratio of three different classes of anthocyanidins, namely, pelargonidin, delphinidin, and cyanidin, and subsequent modifications to structure such as glycosylation, methylation, and acylation [1]
Anthocyanin biosynthesis starts from phenylalanine and produces colorless secondary intermediate metabolites that are sequentially catalyzed by a number of enzymes, including phenylalanine ammonia-lyase (PAL), cinnamic acid 4-hydroxylase (C4H), 4-coumarateCoA ligase (4CL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), flavanone 3′-hydroxylase (F3′H), flavanone 3′5 ′-hydroxylase (F3′5′H), and dihydroflavonol 4-reductase (DFR) [5]
Summary
Flower coloration is one of the most attractive characteristics and quality traits of ornamental plants and has the ability to attract pollinators and seed distributors. Flower color is largely determined by the production of pigments, usually anthocyanins, betalains, or carotenoids. Anthocyanins are major contributors to flower colors. Anthocyanin biosynthesis has been extensively studied in various horticultural plants, for example, Chrysanthemum grandiflorum [2], Begonia semperflorens [3], and Matthiola incana [4]. Two major classes of genes are required for anthocyanin biosynthesis: structural genes and transcription factors (TFs). The structural genes encode the enzymes that are responsible for the biochemical reactions of anthocyanin synthesis. Anthocyanin biosynthesis starts from phenylalanine and produces colorless secondary intermediate metabolites that are sequentially catalyzed by a number of enzymes, including phenylalanine ammonia-lyase (PAL), cinnamic acid 4-hydroxylase (C4H), 4-coumarateCoA ligase (4CL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), flavanone 3′-hydroxylase (F3′H), flavanone 3′5 ′-hydroxylase (F3′5′H), and dihydroflavonol 4-reductase (DFR) [5].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
