Identification of Chalcones and their Contribution to Yellow Coloration in Dahlia (<i>Dahlia variabilis</i>) Ray Florets

Abstract

Yellow color in dahlia flowers is conferred from chalcones, butein and isoliquiritigenin. The color intensity of yellow dahlia cultivars is diverse, but a detailed study on this has not yet been performed. In this study, we first identified structures of flavonoids by nuclear magnetic resonance imaging in ray florets of the red-white bicolor 'Shukuhai', which contains chalcones, flavones and anthocyanins. Four anthocyanins, four flavone derivatives, five isoliquiritigenin derivatives and five butein derivatives were identified. Among the identified compounds, butein 4'-malonylsophoroside is considered to be the final product for butein derivatives and the presence of chalcone 4'-glucosyltransferase, chalcone 4'-glucoside glucosyltransferase, and chalcone 4'glucoside malonyltransferase for isoliquiritigenin and butein modification was predicted. Also, the biosynthetic pathway of butein and isoliquiritigenin derivatives in dahlia with butein 4'-malonylsophoroside as the final product was predicted from the identified compounds. Next, we used nine yellow cultivars and lines with different color intensities and analyzed the correlation between the b* value, an indicator of yellow color, and level of chalcones. There was no difference in the presence or absence of major peaks among the cultivars and lines. Peak area per fresh weight measured by HPLC was high in butein 4'-malonylglucoside, butein 4'-sophoroside and isoliquiritigenin 4'-malonylglucoside, suggesting these three compounds were accumulated abundantly. Among the identified chalcones, the highest correlation coefficient was detected between the b* value and butein 4'-malonylglucoside (r = 0.86), butein 4'-sophoroside (r = 0.82) or isoliquiritigenin 4'malonylglucoside (r = 0.76). These results suggest that these three chalcones confer yellow color in dahlia ray florets. The findings in this study will contribute not only to efforts at breeding new yellow dahlia cultivars, but also to molecular breeding of yellow flowers in other species by introducing the butein biosynthetic pathway.

Identification of a novel chalcone reductase gene for isoliquiritigenin biosynthesis in dahlia (Dahlia variabilis)

“…5D). To expand the experiment, we examined 21 more cultivars whose pigment composition was analyzed previously (Deguchi et al, 2013; Ohno et al, 2011a; 2011b; 2013b; 2021). Again, except for two cultivars (1: ‘Super Girl’ and 5: ‘Magokoro’), P1-P3 bands were detected from cultivars with butein but not from cultivars without butein (Fig.…”

“…Generally, flavonoids are accumulated as a glycoside in vivo , and dahlia accumulates isoliquiritigenin and butein as a 4′-glucoside or its derivatives (Harborne et al, 1990; Ohno et al, 2021). We assumed that tobacco plants are not able to accumulate isoliquiritigenin without glycosylation in vivo due to loss of suitable glucosyltransferase, thus, we tried to co-overexpress CHR (either DvCHR-1 , DvCHR-2 , GmCHR5 or GmCHR6 ) with a snapdragon chalcone 4′-glucosyltransferase ( Am4′CGT ).…”

“…For genotyping of DvCHR , in addition to seven cultivars or seedling lines used for HPLC analysis, 21 cultivars (‘Super Girl’, ‘Yukino’, ‘Cupid’, ‘Atom’, ‘Magokoro’, ‘Saffron’, ‘Gitt’s Attention’, ‘Zannsetsu’, ‘Hakuba’, ‘Hakuyo’, ‘Kokucho’, ‘Fidalgo Blacky’, ‘Ms. Noir’, ‘Kazusa-shiranami’, ‘Black Cat’, ‘Yuino’, ‘Matsuribayashi’, ‘Red Velvet’, ‘Michael J’, ‘Suckle Pico’ and ‘Ittosei’) whose pigment composition was previously analyzed (Deguchi et al, 2013; Ohno et al, 2011a; 2011b; 2013b; 2021) were used. Genomic DNA was extracted with MagExtractor Plant Genome (Toyobo).…”

“…Dahlias ( Dahlia variabilis ) are popular ornamental plants which belong to Asteraceae and are autoallooctoploids with chromosome number 2n = 8x = 64 (Gatt et al, 1998). Dahlia flowers exhibit huge variations in flower color by flavonoid pigments, and many genes associated with flavonoid biosynthesis in ray florets were analyzed (Suzuki et al, 2002; Ohno et al, 2011a; 2011b; 2013b; 2018a; 2021; Deguchi et al, 2013). Although dahlias are able to biosynthesize only flavonoids and do not accumulate carotenoid or betaxanthins in ray florets, there are a lot of bright yellow flower cultivars.…”

The Compositional Aspects of Edible Flowers as an Emerging Horticultural Product

“…Desf. flow-ers (butein and isoliquiritigenin) [84,85]. Li et al [86], in their studies, reported that the edible flowers of Malus pumila Mill.…”