Tree Genetics and Molecular Breeding 2025, Vol.15, No.3, 98-107 http://genbreedpublisher.com/index.php/tgmb 101 developmental stages, and have a strong correlation with the amount of anthocyanins (Niu et al., 2010). The study also found that CHS plays a major role at fruit ripening, while F3H and F3’H are relatively important for the synthesis of flavonoids and phenolic acids during the early fruit growth stage (Duan et al., 2015). 4.3 Identification of regulatory genes in Morella rubra The synthesis of anthocyanins is also controlled by some regulatory factors, mainly three types of proteins: MYB, bHLH and WD40, which together form the MYB-BHLH-WD40 complex. In Morella rubra, MrMYB1 is a very crucial MYB protein, and its expression is consistent with the accumulation of anthocyanins (Niu et al., 2010). MrMYB9 is also a regulatory factor that can promote anthocyanin synthesis (Li et al., 2023). In the bHLH family, the expression of MrbHLH1 and MrMYB1 is synchronous, and the two can combine to form a complex, activating the expression of structural genes. The regulatory ability of MrbHLH2 is relatively weak (Liu et al., 2013b). Among the WD40 family, MrWD40-1 can form a complex together with MrMYB1 and MrbHLH1 to enhance anthocyanin synthesis, but MrWD40-2 does not have this function (Liu et al., 2013a). In addition, MrMYB6 has been found to be a negative regulatory factor. It can bind to other proteins and inhibit the synthesis of anthocyanins and proanthocyanidins (Figure 2) (Shi et al., 2021). Figure 2 MrMYB6 expression pattern during bayberry fruit development (Adopted from Shi et al., 2021) Image caption: (A) The bayberry fruits at 57, 71, 85, 99, and 113 days after full bloom (DAFB) used in this study. Scale bar represents 1 cm. (B) Expression levels of MrMYB6 at different stages. The data were normalized to the MrACT expression level. Error bars indicate the mean ± SE of three replicate reactions. Letters (a, b, c, and d) represent significant difference between wild-type and transgenic plants according to the Duncan’s multiple range test (P < 0.05). (C) Subcellular localization of MrMYB6 in tobacco leaf epidermal cells. Scale bar represents 50 μm (Adopted from Shi et al., 2021) 5 Gene Expression Patterns and Regulation 5.1 Temporal and spatial expression during fruit development Genes related to anthocyanin synthesis show significant temporal and spatial expression differences during fruit development. Research has found that when fruits are close to ripening, the content of anthocyanins increases significantly. The distribution of anthocyanins is also different between the peel and the pulp. Take sweet cherries and red pears as examples. Structural genes such as PacANS, ANS and UFGT have the highest expression levels
RkJQdWJsaXNoZXIy MjQ4ODYzNA==