Red Anthocyanins and Yellow Carotenoids Form the Color of Orange-Flower Gentian (Gentiana lutea L. var. aurantiaca)

Abstract

Flower color is an important characteristic that determines the commercial value of ornamental plants. Gentian flowers occur in a limited range of colors because this species is not widely cultivated as a cut flower. Gentiana lutea L. var. aurantiaca (abbr, aurantiaca) is characterized by its orange flowers, but the specific pigments responsible for this coloration are unknown. We therefore investigated the carotenoid and flavonoid composition of petals during flower development in the orange-flowered gentian variety of aurantiaca and the yellow-flowered variety of G. lutea L. var. lutea (abbr, lutea). We observed minor varietal differences in the concentration of carotenoids at the early and final stages, but only aurantiaca petals accumulated pelargonidin glycosides, whereas these compounds were not found in lutea petals. We cloned and sequenced the anthocyanin biosynthetic gene fragments from petals, and analyzed the expression of these genes in the petals of both varieties to determine the molecular mechanisms responsible for the differences in petal color. Comparisons of deduced amino acid sequences encoded by the isolated anthocyanin cDNA fragments indicated that chalcone synthase (CHS), chalcone isomerase (CHI), anthocyanidin synthase 1 (ANS1) and ANS2 are identical in both aurantiaca and lutea varieties whereas minor amino acid differences of the deduced flavonone 3-hydroxylase (F3H) and dihydroflavonol 4-reductase (DFR) between both varieties were observed. The aurantiaca petals expressed substantially higher levels of transcripts representing CHS, F3H, DFR, ANS and UDP-glucose:flavonoid-3-O-glucosyltransferase genes, compared to lutea petals. Pelargonidin glycoside synthesis in aurantiaca petals therefore appears to reflect the higher steady-state levels of pelargonidin synthesis transcripts. Moreover, possible changes in the substrate specificity of DFR enzymes may represent additional mechanisms for producing red pelargonidin glycosides in petals of aurantiaca. Our report describing the exclusive accumulation of pelargonidin glycosides in aurantiaca petals may facilitate the modification of gentian flower color by the production of red anthocyanins.

Molecular and morphological characterization of new interspecific hybrids of alstroemeria originated from A. caryophylleae scented lines

“…Flower color polymorphism is due to variation in floral pigments, particularly anthocyanins and a predominance of pink, purple and blue with white combinations has been described as the result of changes and single mutations in the anthocyanin pathway (Richards 1986). In our study, orange and red colors were lost after hybridization probably due to changes in the biosynthesis pathway of anthocyanins and/or carotenoids, which responsible for those colours in flowers (Berman et al 2016), confirming the high polymorphism previously observed in other species. Warren and Mackenzie (2001) have considered that flower color is also regulated by selection related to environmental heterogeneity and stress tolerance.…”

Phytochemical variation among populations of Fouquieria splendens Engelm. (Fouquieriaceae)

“…splendens with strong red to reddishorange flowers corroborate the known fact that anthocyanins are the main pigment giving red color, whereas carotenoids are the main pigment giving the yellow and orange colors (Zhu et al 2010). For example, Berman et al (2016) found that a combination of red anthocyanins and yellow carotenoids resulted in the orange color of cultivated Gentiana lutea L. var. aurantiaca.…”

Identification of the Genes Involved in Anthocyanin Biosynthesis and Accumulation in Taxus chinensis

“…Secondary metabolites are the products of plant adaptation to the environment during their evolution. Anthocyanins as a kind of secondary metabolite play a vital role in various processes of plant development, such as providing color to organs to attract pollinators, and of antioxidant activity to protect plants from injury by biotic and abiotic stress [1][2][3][4]. In addition, anthocyanidins are widely used in food, health care products, and drugs for their excellent antioxidant activity [5,6].…”