Bioscience Methods 2024, Vol.15, No.6, 264-274 http://bioscipublisher.com/index.php/bm 266 environmental factors, which can mask the true genetic potential of the plants. The study by Visalakshi et al. (2021) highlighted the high variability in traits such as vine length, number of branches per plant, and root yield per plant, which are influenced by environmental conditions, making it challenging to achieve consistent results. 3.2 Mutation breeding Mutation breeding is another traditional approach that has been used to create genetic diversity in sweet potato. This method involves inducing mutations through physical or chemical agents to generate new genetic variations. Mutation breeding has been successful in developing sweet potato varieties with improved starch properties. For example, the study by Katayama et al. (2006) demonstrated that crossing and mutagenesis could increase the variations of amylose content in sweet potato, leading to the selection of variants with low or high amylose content. The application of mutation breeding has led to the development of new sweet potato cultivars with desirable traits. The "Quick Sweet" cultivar, developed through mutation breeding, features low gelatinization temperatures and altered starch fine structure, making it suitable for various industrial applications (Katayama et al., 2006). This cultivar's starch properties, such as lower gelatinization temperatures and higher proportions of short amylopectin chains, provide excellent cold storage stability, which is beneficial for food processing industries. 3.3 Successful cases: examples and applications of high-yield and high-starch sweet potato variety development Several successful cases of high-yield and high-starch sweet potato variety development have been reported. One notable example is the study by Lin et al. (2007), which investigated the maternal effects on yield and quality traits in sweet potato through reciprocal crosses. The results showed significant positive correlations between top weight, storage root weight, and starch content, indicating the potential for selecting high-yield and high-starch varieties through hybrid breeding. Another successful case is the identification of promising sweet potato genotypes with high genetic variability and potential for selection gains. The study by Otoboni et al. (2020) identified genotypes CERAT31-01, CERAT21-02, and CERAT51-30 as the most promising for high yield and starch content. Similarly, the study by Vargas et al. (2020) recommended the VR13-61 accession for root production and VR13-11 and VR13-22 for dual-aptitude, highlighting the effectiveness of traditional breeding methods in improving sweet potato traits. 4 Application of Marker-Assisted Selection (MAS) in Sweet Potato Breeding 4.1 Principles of marker-assisted selection and its advantages in efficient sweet potato breeding Marker-assisted selection (MAS) is a modern plant breeding technique that leverages molecular markers to select desirable traits in crops. The principle behind MAS is the identification and use of DNA markers that are closely linked to genes of interest, allowing breeders to select plants with favorable traits at the seedling stage, thus bypassing the need for phenotypic selection in mature plants (Francia et al, 2005; Collard and Mackill, 2008; Singh and Singh, 2015). This method significantly accelerates the breeding process by enabling the selection of traits that are difficult to measure directly, such as yield and stress tolerance (Collard and Mackill, 2008; Singh and Singh, 2015). MAS offers several advantages over traditional breeding methods. It allows for the precise transfer of genomic regions of interest, improving the efficiency of breeding programs (Babu et al., 2004; Huang and Hong, 2024). Additionally, MAS can be used for both simply inherited traits and complex polygenic traits, although its application in the latter has been more challenging (Babu et al., 2004; Francia et al, 2005). The integration of MAS with conventional breeding can lead to the development of new cultivars with improved traits in a shorter time frame (Collard and Mackill, 2008; Singh and Singh, 2015). 4.2 Important molecular markers related to yield and starch accumulation and their applications The identification of key molecular markers associated with yield and starch accumulation is crucial for the successful application of MAS in sweet potato breeding. Quantitative trait loci (QTL) mapping studies have
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