Cyanidin-3-O-glucoside Contributes to Leaf Color Change by Regulating Two bHLH Transcription Factors in Phoebe bournei

Abstract

Anthocyanins produce different-colored pigments in plant organs, which provide ornamental value. Thus, this study was conducted to understand the mechanism of anthocyanin synthesis in ornamental plants. Phoebe bournei, a Chinese specialty tree, has high ornamental and economic value due to its rich leaf color and diverse metabolic products. Here, the metabolic data and gene expression of red P. bournei leaves at the three developmental stages were evaluated to elucidate the color-production mechanism in the red-leaved P. bournei species. First, metabolomic analysis identified 34 anthocyanin metabolites showing high levels of cyanidin-3-O-glucoside (cya-3-O-glu) in the S1 stage, which may suggest that it is a characteristic metabolite associated with the red coloration of the leaves. Second, transcriptome analysis showed that 94 structural genes were involved in anthocyanin biosynthesis, especially flavanone 3′-hydroxy-lase (PbF3′H), and were significantly correlated with the cya-3-O-glu level. Third, K-means clustering analysis and phylogenetic analyses identified PbbHLH1 and PbbHLH2, which shared the same expression pattern as most structural genes, indicating that these two PbbHLH genes may be regulators of anthocyanin biosynthesis in P. bournei. Finally, overexpression of PbbHLH1 and PbbHLH2 in Nicotiana tabacum leaves triggered anthocyanin accumulation. These findings provide a basis for cultivating P. bournei varieties that have high ornamental value.

Metabolomics and Transcriptomics Revealed a Comprehensive Understanding of the Biochemical and Genetic Mechanisms Underlying the Color Variations in Chrysanthemums

“…In particular, the glycosylation and acylation products of pelargonidin and cyanidin had high content. Previous studies have shown that pelargonidin 3-O-glucoside and cyanidin 3-O-glucoside and their modified products are important for the purplish-red or red color [ 33 , 34 ]. Although peonidin and delphinidin also had some effect on flower color, there was no significant difference between the two substances in the three cultivars.…”

Integrated transcriptomics and metabolomics analyses provide insights into anthocyanin biosynthesis for leaf colour formation in Quercus mongolica

“…In acer tri orum, cyanidin-3-O-arabinoside is closely related to red leaf colour [36]. The major anthocyanin in the leaves of Phoebe bournei is cyanidin-3-O-glucoside [27].…”

“…For example, cyanidin-3,5-O-diglucoside is the major anthocyanin for the production of red leaves in Acer pseudosieboldianum, and PAL, ANS, DFR, and F3'H are structural genes involved in leaf colour production [26]. In a study on Phoebe bournei [27], cyanidin-3-O-glucoside was suggested to be a metabolite associated with red leaf colouration, and avanone 3'-hydroxy-lase (PbF3'H) was signi cantly associated with cyanidin-3-O-glucoside.…”

Pigment Diversity in Leaves of Caladium × hortulanum Birdsey and Transcriptomic and Metabolic Comparisons between Red and White Leaves

“…acephala de Candolle), the white color of the inner leaves is attributed to an extremely low or absent level of anthocyanin biosynthesis, coupled with high chlorophyll degradation and minimal chlorophyll biosynthesis [ 6 ]. In Phoebe bournei , Wang et al [ 7 ] discovered that the anthocyanin content gradually decreased as the leaves developed. They suggested that the anthocyanin cyanidin-3- O -glucoside and the PbF3′H , PbbHLH1 , and PbbHLH2 genes are likely to be responsible for the red leaf color.…”