Bioscience Methods 2025, Vol.16, No.2, 60-69 http://bioscipublisher.com/index.php/bm 62 Stress tolerance is a critical focus area of breeding, especially in response to challenges such as drought, salinity, and pests. Breeding programs aim to develop varieties that can withstand these stresses to ensure stable production. For example, transgenic sweet potato lines expressing genes such as cry8Db and cry7A1 have shown reduced weevil infestation, while those expressing the oryzacystatin-1 (OC1) gene have demonstrated enhanced resistance to nematodes and viruses (Imbo et al., 2016). Additionally, the study of drought tolerance mechanisms and the identification of drought-tolerant genotypes are essential for breeding programs targeting regions prone to water scarcity (Laurie et al., 2022; Sapakhova et al., 2023). Nutritional enhancement and biofortification are increasingly important objectives. Breeding efforts are focused on increasing the content of essential micronutrients, such as iron, zinc, and vitamins, in sweet potato varieties. For instance, orange-fleshed sweet potato cultivars like Bophelo have been identified for their superior nutritional content, including higher levels of Fe, Zn, and dietary fiber, which are crucial for addressing malnutrition (Laurie et al., 2022). Biofortification through both conventional breeding and genetic engineering is being pursued to develop varieties with enhanced nutritional profiles (Diepenbrock and Gore, 2015; Garg et al., 2018; Medina-Lozano and Díaz, 2022). 3.2 Key Institutions Involved in Breeding Efforts Several key institutions are at the forefront of sweet potato breeding in China. These include the Chinese Academy of Agricultural Sciences (CAAS), which leads research and development in crop improvement, including sweet potato breeding. The International Potato Center (CIP) collaborates with Chinese institutions to enhance sweet potato varieties for better yield, stress tolerance, and nutritional value. Local Agricultural Research Institutes also play a significant role by conducting region-specific breeding programs to address local agricultural challenges and improve sweet potato production. 3.3 Advances in breeding techniques Conventional breeding methods remain a cornerstone of sweet potato improvement. These methods involve selecting parent plants with desirable traits and cross-breeding them to produce offspring with enhanced characteristics. This approach has been instrumental in developing high-yielding and stress-tolerant varieties (Obidiegwu et al., 2015; Tiwari et al., 2022). Molecular breeding and marker-assisted selection (MAS) have revolutionized sweet potato breeding by enabling the precise identification and incorporation of beneficial traits. Techniques such as genomic selection and the use of molecular markers linked to stress tolerance and nutritional traits have accelerated the development of improved varieties (Lau et al., 2018; Medina-Lozano and Díaz, 2022). Genomic selection and CRISPR/Cas genome editing are cutting-edge technologies being applied in sweet potato breeding. Genomic selection involves using genome-wide markers to predict the performance of breeding lines, thereby speeding up the selection process. CRISPR/Cas technology allows for precise editing of the sweet potato genome to introduce or enhance specific traits, such as drought tolerance and pest resistance (Imbo et al., 2016; Lau et al., 2018). These advanced techniques hold great promise for the future of sweet potato breeding, enabling the development of varieties that can meet the growing demands for food security and nutritional quality. 4 Utilization of Genetic Resources in Sweet Potato Breeding 4.1 Strategies for genetic diversity utilization The utilization of genetic diversity is crucial for improving sweet potato breeding programs. Genetic diversity provides a pool of traits that can be harnessed to enhance crop resilience, yield, and nutritional quality. In sweet potato breeding, strategies to utilize genetic diversity include the assessment of population structure and genetic diversity using molecular markers (Zhu et al., 2024). For instance, a study on sweet potato accessions in China used 62,363 SNPs to evaluate genetic diversity, revealing significant within-group diversity and identifying a core germplasm set that can be used for future breeding efforts (Figure 1) (Su et al., 2017). This approach ensures a broad genetic base and is essential for the long-term sustainability of the breeding programs.
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