Bioscience Methods 2024, Vol.15, No.6, 264-274 http://bioscipublisher.com/index.php/bm 270 7.3 Proteomics and epigenomics Proteomics and epigenomics offer valuable insights into the roles of proteins and epigenetic modifications in regulating yield and starch synthesis. Proteomic analyses have identified numerous proteins associated with starch metabolism and yield traits. For instance, a study on potato tubers identified over 300 protein spots associated with various quality traits, including starch content (Acharjee et al., 2018). These proteins can serve as potential targets for improving starch synthesis and yield in sweet potato. Additionally, epigenetic modifications, such as DNA methylation and histone modifications, play a crucial role in regulating gene expression and can influence starch biosynthesis and yield. Integrating proteomics and epigenomics with other omics approaches can provide a comprehensive understanding of the molecular mechanisms underlying yield and starch content in sweet potato (Ritchie et al., 2015; Yang et al., 2021). 8 Integrated Breeding Strategies for Sweet Potato Improvement 8.1 Integration of traditional and modern techniques A multi-level breeding strategy that combines traditional breeding, marker-assisted selection (MAS), genomic selection, and gene editing is essential for the improvement of sweet potato yield and starch content. Traditional breeding methods have been foundational in selecting desirable traits such as high yield and disease resistance (Kar et al., 2022). However, integrating modern techniques like CRISPR/Cas9-based genome editing has shown significant promise. For instance, CRISPR/Cas9-mediated mutagenesis of starch biosynthetic genes in sweet potato has been effective in modifying starch quality without significantly altering total starch content (Wang et al., 2019). Additionally, the overexpression of genes like IbVP1 and IbSnRK1 has been shown to enhance starch content and yield by regulating carbohydrate metabolism and starch biosynthesis pathways (Ren et al., 2018; Fan et al., 2021). These modern techniques, when combined with traditional breeding, can accelerate the development of superior sweet potato cultivars. 8.2 Multi-trait selection strategy Optimizing additional traits alongside yield and starch content is crucial for the holistic improvement of sweet potato. Traits such as disease resistance, stress tolerance, and nutritional quality should be considered. For example, the overexpression of IbVP1 not only improves starch content but also enhances photosynthesis and sucrose transport, which are vital under stress conditions (Fan et al., 2021). Similarly, the selection of genotypes with high beta-carotene content can address nutritional deficiencies while maintaining high yield and starch content (Lamaro et al., 2023). The use of polyploid genome-wide association studies (GWAS) has also been instrumental in identifying molecular markers associated with complex traits, enabling the selection of genotypes with a combination of desirable traits (Haque et al., 2023). 8.3 Case studies in integrated breeding Real-life examples of applying integrated breeding methods in sweet potato improvement highlight the effectiveness of these strategies. One notable case is the use of CRISPR/Cas9 to target starch biosynthetic genes, resulting in modified starch quality in sweet potato cultivars Xushu22 and Taizhong6 (Wang et al., 2019). Another example is the overexpression of the IbVP1 gene, which significantly increased starch content and yield by enhancing photosynthesis and sucrose transport (Figure 2) (Fan et al., 2021). Overexpression of the IbVP1 gene significantly increased the yield and inorganic phosphorus content in the storage roots of sweet potato, with particularly outstanding results in transgenic lines IA7 and IA8. Phosphorus is an essential nutrient for plant growth and development. This study demonstrates that regulating phosphorus metabolism-related genes can effectively enhance crop yield and nutritional value, providing potential genetic resources and theoretical support for the genetic improvement of high-yield sweet potato cultivation. Additionally, the development of the "Quick Sweet" cultivar through traditional breeding and selection for specific starch properties demonstrates the potential of combining traditional and modern techniques (Katayama et al., 2006). These case studies underscore the importance of an integrated approach in achieving substantial improvements in sweet potato yield and starch content.
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