Molecular Plant Breeding 2025, Vol.16, No.2, 133-145 http://genbreedpublisher.com/index.php/mpb 138 5.3 Implications for breeding programs The genetic diversity uncovered by these genomic studies has significant implications for sweet potato breeding programs. The high level of genetic variation provides a valuable resource for the selection of desirable traits such as high yield, disease resistance, and improved nutritional content. For example, the identification of genotypes with high beta-carotene content and other desirable traits can be used to develop new, improved sweet potato varieties (Otoboni et al., 2020). Moreover, understanding the genetic relationships and diversity among sweet potato accessions can help breeders maintain a diverse gene pool, which is essential for the long-term sustainability of breeding programs (Lee et al., 2019; Paliwal et al., 2020; Meng et al., 2021). The use of molecular markers in breeding programs can also facilitate marker-assisted selection, making the breeding process more efficient and targeted (Paliwal et al., 2020; Meng et al., 2021). 6 Epigenetic Modifications and Gene Regulation in Sweet Potato 6.1 The role of epigenetic changes in nutrient and yield traits Epigenetic modifications, such as DNA methylation and histone modifications, play a crucial role in regulating gene expression without altering the DNA sequence. These modifications can significantly impact plant development, stress responses, and ultimately, crop yield and nutrient composition. DNA methylation, in particular, has been shown to influence various developmental and physiological processes in plants, including tuberization in potatoes under high-temperature stress (Dutta et al., 2022). Similarly, in sweet potatoes, DNA methylation and other epigenetic mechanisms likely regulate key genes involved in nutrient biosynthesis and storage root development, thereby affecting yield and nutritional quality. Histone modifications and chromatin remodeling also contribute to the regulation of gene expression in response to environmental cues and internal signals. These epigenetic changes can modulate the chromatin state, making genes more or less accessible for transcription, which in turn affects plant growth and adaptation to stress (Hewezi, 2017; Agarwal et al., 2020). For instance, the interplay between DNA methylation and histone modifications has been implicated in the regulation of anthocyanin biosynthesis in sweet potato storage roots, highlighting the importance of epigenetic regulation in determining phenotypic traits (Zhang et al., 2020b). 6.2 Case studies on epigenetic influence in sweet potato adaptation Several studies have demonstrated the role of epigenetic modifications in plant adaptation to environmental stresses. In potatoes, high temperatures induce the expression of positive regulators of tuberization through active DNA demethylation and RNA-directed DNA methylation pathways, suggesting a similar mechanism could be at play in sweet potatoes (Dutta et al., 2022). This adaptive response is crucial for maintaining yield under stress conditions. In another study, the manipulation of DNA methylation and histone acetylation in the green alga Chlamydomonas reinhardtii showed that reducing epigenetic variation can hinder adaptation to different environmental stresses, indicating that epigenetic diversity is essential for adaptive evolution (Kronholm et al., 2017). This finding underscores the potential of epigenetic modifications to enhance stress tolerance and adaptation in sweet potatoes. Furthermore, research on fruit development has shown that epigenetic regulation, including DNA methylation and histone modifications, is vital for processes such as ripening. For example, the dysfunction of a DNA demethylase delayed ripening in tomatoes, and the application of DNA methylation inhibitors altered the ripening process in various fruit species (Tang et al., 2020). These insights suggest that similar epigenetic mechanisms could be leveraged to improve sweet potato yield and quality by modulating developmental processes and stress responses. 7 Genomic Breeding Strategies for Sweet Potato Improvement 7.1 Application of CRISPR/Cas9 in sweet potato gene editing CRISPR/Cas9 technology has emerged as a powerful tool for precise genome editing in various crops, including sweet potato. This system allows for targeted mutations in specific genes, facilitating the rapid development of new germplasm with desirable traits. For instance, CRISPR/Cas9 has been successfully used to edit starch biosynthetic genes in sweet potato, resulting in modifications to starch quality without significantly altering total
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