Plant Gene and Trait 2025, Vol.16, No.1, 32-38 http://genbreedpublisher.com/index.php/pgt 33 yellow petals. Jia et al. (2021) hold that carotenoids, such as lutein and zeaxanthin, are the key to the formation of yellow petals, especially the flower color of ornamental varieties. Zeng et al. ’s research in 2023 indicates that some flavonols, such as tamarixetin and kaempferol, may affect the detailed changes in petal color. 2.2 Known pathways and genes influencing pigment biosynthesis The color change of rapeseed flowers is related to the synthesis of pigments in the body, mainly including two metabolic pathways: flavonoids and carotenoids. Hao et al. (2022) demonstrated in their research that genes like BnaANS and BnaDFR are involved in the synthesis of anthocyanins, which are crucial for the formation of red or purple petals. Li et al. (2023) discovered that the role of the BnaF3’Hgene is to add hydroxyl groups to flavonoid molecules, influencing the color transition of petals from yellow to purple. The synthesis of carotenoids is controlled by the BnaCRTISOgene, which can balance the contents of lycopene and beta-carotene and regulate whether flowers turn yellow or orange (Li et al., 2022). 2.3 Regulatory networks involved in flower color formation Transcription factors such as MYB and bHLH (for example, BnaPAP2 and BnaGL3) are crucial for the synthesis of anthocyanins. They usually combine into a complex, turning on the switch of the related genes. Some hormones, such as jasmonic acid, also help activate these synthetic pathways to increase pigments when plants are under stress (Luo et al., 2021). External conditions such as light and temperature can also affect the expression of pigment-related genes. These factors combined make the color changes of rapeseed flowers more complex (Zeng et al., 2023). 3 Regulation and Expression of Flower Color Genes 3.1 Spatiotemporal expression patterns of key genes In rapeseed, genes such as BnaANS (anthocyanin synthase) and BnaF3’H (flavonoid 3’ -hydroxylase) are expressed differently in the petals, which can cause variations in the depth and hue of the flower color (Hao et al., 2022). Li et al. ’s research in 2020 also found that the expression sites of transcription factors such as MYB and bHLH in related plants are relatively limited. They only function in specific regions, influencing where pigments accumulate and ultimately making the color distribution of flowers look very special. 3.2 Epigenetic regulation and its impact on flower color Yang et al. (2015) found in Arabidopsis thaliana and Brassica plants that changes in methylation levels on promoters would affect the activity of these synthetic genes during the development of flowers. Wu et al. ’s research in 2020 suggests that modifications to histones and changes in chromatin structure also precisely regulate the expression of these key genes, enabling them to respond to environmental changes or developmental stages. 3.3 Environmental influences on gene expression In rapeseed, different light rays can change the activity of photosensitive pigment interaction factors (PIFs), and these factors will further regulate the synthesis pathway of pigments (Li et al., 2021). When the temperature changes, regulatory factors such as MYB and bHLH are also affected, thereby altering the accumulation of anthocyanins. Luo et al. (2021) hold that this indicates that the expression of flower color genes can respond to changes in the external environment. 4 Evolutionary Perspective on Flower Color Genes 4.1 Evolution of pigmentation genes in the Brassica genus whole-genome triplication (WGT) has led to the duplication of some genes, laying the foundation for their subsequent different divisions of labor. The BnaZEP gene family related to carotenoid synthesis shows functional division of labor in different tissues. Some homologous genes are mainly expressed in petals, while others are more active in leaves. Liu et al. (2020) hold that this indicates that after gene duplication, the way of pigment synthesis becomes more flexible, which is helpful for plants to play a better role in reproduction and ecology. Mutations on some regulatory genes, such as changes in the promoter of flavonoid synthesis genes, also indicate that evolution is very important for the regulation of pigments in Brassica plants.
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