Rice Genomics and Genetics 2024, Vol.15, No.6, 265-276 http://cropscipublisher.com/index.php/rgg 273 A deeper comprehension of the multifaceted roles of anthocyanins in dark purple rice will enable researchers to more fully recognize the significance of these compounds in plant adaptation and resilience. The modulation of anthocyanin biosynthesis through genetic and environmental factors presents a promising avenue for enhancing crop quality and stress tolerance in agricultural practices. 7 Applications and Future Perspectives 7.1 Breeding strategies for improved anthocyanin production Strategies for the breeding of dark purple rice may be enhanced by the exploitation of the natural variations in R2R3-MYB gene promoters and their regulatory networks (Li et al., 2020). The selection and cross-breeding of rice varieties with high expression levels of R2R3-MYB genes may facilitate the development of new cultivars with increased anthocyanin content. For example, the OsC1 gene in black rice has been demonstrated to have a positive correlation with anthocyanin biosynthesis, indicating that breeding programs could prioritize this gene to enhance anthocyanin production (Upadhyaya et al., 2021). Furthermore, an understanding of the genetic basis of anthocyanin accumulation, as observed in the pl6 mutant, can provide valuable insights into breeding strategies (Khan et al., 2020). 7.2 Genetic engineering approaches targeting R2R3-MYBgenes Genetic engineering provides precise tools for the manipulation of R2R3-MYB genes, which can be employed to enhance anthocyanin production (Wang et al., 2010). Techniques such as CRISPR/Cas9 can be employed to edit the promoters or coding regions of these genes, thereby enhancing their expression. The overexpression of R2R3-MYB genes, such as OsC1, has been demonstrated to increase anthocyanin levels and improve oxidative stress tolerance in rice (Upadhyaya et al., 2021). Moreover, the integration of multiple R2R3-MYB activators into the rice genome could result in a synergistic enhancement of anthocyanin biosynthesis, as these TFs often function in concert with other regulatory proteins (Zhang et al., 2020; Yan et al., 2021; Yang et al., 2022). 7.3 Potential for developing stress-resistant rice varieties It is established that anthocyanins possess antioxidant properties, which enable plants to mitigate oxidative stress. The manipulation of R2R3-MYBgenes can enhance anthocyanin production, thereby developing rice varieties that are more resistant to environmental stresses, including high light intensity, temperature fluctuations, and oxidative damage. For example, the OsC1 gene has been demonstrated to not only increase anthocyanin content but also to improve photosynthetic efficiency and reduce membrane damage under stress conditions (Upadhyaya et al., 2021). Similarly, the pl6 mutant demonstrates that elevated anthocyanin levels can augment the plant's antioxidant capacity, thereby providing a robust defense against reactive oxygen species (ROS) (Khan et al., 2020). 7.4 Future research Future research should concentrate on elucidating the intricate regulatory networks involving R2R3-MYB genes and their interactions with other TFs and environmental signals. While considerable progress has been made in elucidating the function of R2R3-MYBgenes in anthocyanin biosynthesis, numerous questions remain unanswered. For example, further investigation is required to elucidate the specific upstream regulators and epigenetic modifications that control R2R3-MYBgene expression (Naing and Kim, 2018; Yang et al., 2022; Zuo et al., 2023). Furthermore, it is essential to investigate the potential trade-offs between high anthocyanin production and other agronomic traits, such as yield and stress tolerance, to develop commercially viable rice varieties. Ultimately, the integration of multi-omics methodologies, encompassing genomics, transcriptomics, and metabolomics, can facilitate a comprehensive elucidation of the anthocyanin biosynthetic pathway and its regulatory mechanisms in rice (Yan et al., 2021). 8 Concluding Remarks The research on the environmental modulation of R2R3-MYB gene expression in dark purple rice has yielded significant insights into the regulation of anthocyanin biosynthesis and plant adaptation. Notable findings include the identification of R2R3-MYB TFs as pivotal regulators of anthocyanin biosynthetic genes (ABGs). These TFs are subject to influence from a range of environmental factors, including light, temperature, and internal signals
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