Rice Genomics and Genetics 2024, Vol.15, No.6, 265-276 http://cropscipublisher.com/index.php/rgg 272 reproductive processes. Furthermore, the increased stress tolerance afforded by anthocyanins facilitates superior seed development and quality in dark purple rice. The regulatory role of MYB TFs in anthocyanin biosynthesis is of great importance for the maintenance of these benefits, as they control the expression of genes involved in both the early and late stages of anthocyanin production (Shin et al., 2016; Kim et al., 2021; Yan et al., 2021) (Figure 3). However, in general, dark purple rice is understood to exhibit lower quantitative and quality characteristics than white rice. It is plausible that the pigment composition of the pericarp exerts a direct influence on these traits on rice yield and eating quality. Figure 3 Proposed model of anthocyanin biosynthesis of seed and vegetative tissue in rice (Adopted from Kim et al., 2021) Image caption: (A) Heat map diagram of expression level for anthocyanin regulators consisting of MYB (M), bHLH (B), and WD40 (W) from rice pericarp and leaf, respectively. Color scale indicates fold changes in gene expression. (B) Working models of anthocyanin coloration in different tissues of rice. Both OsKala3 and OsKala4 had extremely high expression levels in rice pericarp, while OsC1 and OsRb were more strongly expressed in respective rice leaf. When all of OsDFR was functional, it forms the functional MBW complex consisting of OsKala3-OsKala4-OsTTG1 and OsC1-OsRb-OsTTG1 activating anthocyanin biosynthesis in rice (Adopted from Kim et al., 2021) 6.4 Ecological implications and potential advantages in natural habitats The ecological implications of anthocyanin modulation in dark purple rice are of considerable significance. The presence of anthocyanins confers a competitive advantage in natural habitats, enhancing the plant's ability to withstand a range of environmental stresses, including cold, salt, and light. The up-regulation of anthocyanin biosynthesis genes in response to these stresses, which is mediated by R2R3-MYB TFs, indicates that anthocyanin-rich plants are better adapted to fluctuating environmental conditions. This adaptive advantage may result in enhanced survival and proliferation in diverse ecological niches (Shin et al., 2016; Karppinen et al., 2022; Yang et al., 2022).
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