Bioscience Methods 2025, Vol.16, No.1, 23-32 http://bioscipublisher.com/index.php/bm 27 4.4 Enhancing stress tolerance (drought, salinity, and pest resistance) for stable yields Stress tolerance is crucial for maintaining stable yields in sweet potato cultivars, especially under adverse environmental conditions. Molecular breeding techniques have been utilized to enhance tolerance to drought, salinity, and pests. Genetic selection and genome editing tools, such as CRISPR-Cas9, have been used to introduce or modify genes that confer resistance to these stresses. By improving the plant's ability to withstand environmental challenges, these molecular approaches ensure consistent and high yields even in suboptimal growing conditions (Otoboni et al., 2020; Tiwari et al., 2020). In summary, the integration of advanced molecular techniques in sweet potato breeding programs holds significant promise for developing high yield cultivars. By focusing on yield-related traits, photosynthetic efficiency, storage root development, and stress tolerance, researchers can create robust sweet potato varieties capable of meeting the growing food demand (Basu et al., 2018). 5 Case Study: Genetic Resource Utilization for Sweet Potato Breeding in China 5.1 Overview of molecular breeding projects in China China has been actively involved in molecular breeding projects to enhance the yield and quality of sweet potato cultivars. These projects leverage advanced biotechnological tools such as SSR markers and RNA-seq to identify and utilize genetic diversity within sweet potato germplasm. For instance, the phenotypic and genetic diversity analysis of potato cultivars in China has provided a framework for similar studies in sweet potatoes, highlighting the importance of molecular markers in breeding programs (Hu et al., 2022). Additionally, the integration of market segment needs into breeding strategies has been emphasized to ensure that new cultivars meet the demands of various stakeholders, including those focused on poverty alleviation and nutrition (Ojwang' et al., 2023). 5.2 Key high-yield cultivars developed through molecular techniques Several high-yield sweet potato cultivars have been developed through molecular breeding techniques in China. For example, the use of selection indexes and genetic parameters has led to the identification of promising genotypes such as CERAT31-01, CERAT21-02, and CERAT51-30, which exhibit high beta-carotene content and significant yield potential (Otoboni et al., 2020). Moreover, the evaluation of sweet potato genotypes through crossbreeding has resulted in the development of cultivars like CERAT16-20 and CERAT31-1, which are noted for their high productivity and suitability for both household consumption and industrial use (Oliveira et al., 2022). 5.3 Challenges and achievements in breeding programs Breeding programs in China have faced several challenges, including the need to balance genetic diversity with the selection of high-yield traits. The high genetic variability within sweet potato populations has been both a challenge and an opportunity, requiring sophisticated selection strategies to achieve genetic gains (Vargas et al., 2020). Despite these challenges, significant achievements have been made, such as the development of genotypes with high dry matter content and resistance to sweet potato virus disease (SPVD), which are crucial for stable and high yields. Additionally, the use of genotype-by-environment interaction analysis has been instrumental in identifying genotypes that perform well across diverse environmental conditions (Ngailo et al., 2019). 5.4 Lessons learned for global sweet potato breeding initiatives The experiences from China's molecular breeding projects offer valuable lessons for global sweet potato breeding initiatives. One key lesson is the importance of integrating molecular techniques with traditional breeding methods to enhance the efficiency and effectiveness of breeding programs. The success of using SSR markers and RNA-seq in identifying valuable genetic traits can be replicated in other regions to improve sweet potato cultivars (Hu et al., 2022; Wei et al., 2023). Furthermore, the focus on market-driven breeding strategies ensures that new cultivars meet the specific needs of different regions, thereby maximizing their impact on food security and nutrition (Ojwang et al., 2023). Lastly, the emphasis on genetic diversity and the use of advanced statistical tools for genotype evaluation can help other countries develop robust and high-yield sweet potato cultivars (Ngailo et al., 2019; Otoboni et al., 2020; Vargas et al., 2020).
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