Plant Gene and Trait 2025, Vol.16, No.1, 32-38 http://genbreedpublisher.com/index.php/pgt 34 4.2 Comparative genomics of flower color traits across related species There is a study conducted genomic comparisons of rapeseed and its two diploid ancestors - Brassica rapa and Brassica oleracea, and found that they have similarities as well as differences in flower color genetics. Some key genes in anthocyanin synthesis are conconservative in these species, indicating that their functions remain basically unchanged. However, the expression patterns of these genes have changed due to different regulatory mechanisms. Ye et al. ’s research in 2022 demonstrated that the BnaA07.PAP2 gene in rapeseed has variations in the promoter region, making it more prone to accumulating anthocyanins and forming apricot and pink petals, which are not common in its two ancestral species. 4.3 Adaptive significance of flower color variation in rapeseed The bright petals are controlled by pigment genes like BnaCRTISO, which can better attract pollinating insects and are important for the reproduction of both wild and cultivated species. Li et al. (2022) found that some gene mutations related to carotenoid synthesis, such as the one that turns petals milky white, have been used to cultivate ornamental rapeseed varieties, making the use of rapeseed not only as grain and oil but also increasing its ornamental value. Flower color genes are beneficial for plants to adapt to the environment and have also played a role in artificial breeding, making rapeseed more important in both agriculture and ornamental plants. 5 Environmental and Physiological Influences on Flower Color 5.1 Role of temperature, light, and soil nutrients in pigment biosynthesis Low temperatures can enhance the expression of genes like BnaPAP1 and BnaTT8, causing more anthocyanins to accumulate and making the petal color purpler and brighter. Ye et al. ’s research in 2022 found that the anthocyanin content in plants significantly increased in cold environments, indicating that these genes were activated. Li et al. (2022) hold that the type of light is also crucial. Red and blue light can activate the BnaCRTISO gene, facilitating the synthesis of carotenoids and making the petal color more distinct. Kumar et al. (2021) ’s research indicates that soil nutrients such as nitrogen and sulfur also affect the generation process of anthocyanins and flavonoids, suggesting that these nutrients are also crucial for maintaining bright flower colors. 5.2 Interaction between genetic and environmental factors Some variations in regulatory genes, such as changes in the promoter region of the BnaA07.PAP2 gene, make it more sensitive to external conditions such as light and temperature, and it is easier for anthocyanins to accumulate in a suitable environment, resulting in brighter flower colors (Ye et al., 2022). Chen et al. (2022) ’s transcriptome research found that environmental stresses such as drought and ultraviolet rays can enhance the expression of genes related to pigments, indicating that these genes have the ability to help plants cope with adverse environments. 5.3 Physiological changes affecting pigment stability and intensity For anthocyanins and carotenoids to function properly, a stable state needs to be maintained inside the cells. Liu et al. (2020) found that the two genes, BnaDFRand BnaANS, regulate the pH of vacuoles and act together with some auxiliary pigments, which is beneficial for anthocyanins to maintain their color without fading easily and make the color appear brighter. Li et al. (2022) hold that the color of carotenoids also depends on the reduction of other metabolic pathways in the body, which can prevent the decomposition of pigments and make yellow or orange more prominent. 6 Case Studies of Flower Color Genes in Rapeseed 6.1 Identification and functional characterization of BnaPAP1 The BnaPAP1 gene is a “relative” of the PAP1 gene in Arabidopsis thaliana and plays a very crucial regulatory role in the synthesis process of anthocyanins. This gene in rapeseed will produce different versions (called isomers) through “splicing”, and their functions are also different. BnaPAP1-744 and some shorter variants have different effects on anthocyanin accumulation at the site of the flower. BnaPAP1 in purple rapeseed (PR) causes a large accumulation of anthocyanins in the leaves, thus giving the leaves a bright purple color. Under the microscope, it can be seen that anthocyanins are mainly concentrated in vacuoles, which proves that BnaPAP1 does play a role in anthocyanin synthesis (Figure 1). Chen et al. (2020) also found that BnaPAP1 can initiate the expression of genes related to anthocyanin synthesis, which is why the petals of rapeseed can turn purple.
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