Transcriptomic and Chemical Analyses Reveal the Hub Regulators of Flower Color Variation from Camellia japonica Bud Sport

Abstract

Camellia japonica is a woody ornamental plant with multiple flower color variations caused by bud sport; however, the molecular mechanism remains unclear. Here, chemical and transcriptomic analyses of C. japonica were performed with white, pink, red, and dark red flowers caused by bud sport. Seven anthocyanins were detected in these samples, except in C. japonica ’YuDan’ (white petals). The total anthocyanin content of C. japonica ’JinBiHuiHuang’ was the highest, and cyanidin 3-O-β-glucoside (Cy3G) was the main anthocyanin affecting the redness of petals. Furthermore, the ratio of Cy3G and cyanidin-3-O-(6-O-(E)-p-coumaroyl)-B-glucoside) was significantly correlated with the red petal phenotype. In total, 5673 genes were identified as differentially expressed genes (DEGs). The potential co-expression modules related to anthocyanin accumulation were established, which featured transcription factors, anthocyanin biosynthesis, and plant hormone signal transduction. Thirteen structural genes in the anthocyanin biosynthetic pathway were identified as DEGs, most of them were upregulated with deepening of flower redness. An integrated promoter and cluster analysis suggested that CjMYB62, CjMYB52, and CjGATA may play important roles in anthocyanin accumulation. These results provide insight and candidate genes for the transcriptional mechanism responsible for the bud sport phenotype.

Camellia japonica Flowers as a Source of Nutritional and Bioactive Compounds

“…DT and HA obtained the lowest TAC with no statistical differences (<24 g cyanidin-3-glycoside/g sample), which corresponds to pink blush flowers. According to Fan, TAC of C. japonica of different ecotypes ranged from 3.83 to 149.34 mg anthocyanin/100 mg [96]. Similar results were reported by Xiaowei, with an average content of anthocyanins of 0.828 mg anthocyanin/g sample [97].…”

Genome-wide identification of GATA transcription factors in tetraploid potato and expression analysis in differently colored potato flesh

“…Previous findings confirmed that GATA TFs may be directly or indirectly involved in anthocyanin biosynthesis ( Zhou et al., 2020 ; Fu et al., 2021 ; Wang et al., 2021 ; Fan et al., 2022 ; Zhou et al., 2022 ). Cho et al.…”

“…(2021) screened 19 key TFs involved in anthocyanin accumulation from five Camellia japonica cultivars with different petal colors using RNA-seq, including one GATA transcription factor that positively regulated target gene expression. Fan et al. (2022) cloned candidate genes related to anthocyanin synthesis from Camellia japonica and identified GATA binding sites in their promoter regions.…”

Genomics insights into flowering and floral pattern formation: regional duplication and seasonal pattern of gene expression in Camellia

“…Many studies have shown that the petal pigments in camellias are mainly derived from anthocyanins, with the red color being mainly from anthocyanins of the cyanidin glycosides [ 9 ], while the yellow pigment is mainly from the quercetin glycosides [ 8 ]. Although there have been some studies on the genes regulating petal flower color in different ornamental camellias [ 10 ], little is known about the molecular mechanisms underlying floral color domestication.

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