Plant Gene and Trait 2024, Vol.15, No.6, 305-313 http://genbreedpublisher.com/index.php/pgt 307 et al., 2017; Budhlakoti et al., 2022). GS can accelerate the breeding cycle by reducing the need for extensive phenotyping and allowing for the selection of superior genotypes based on their genomic estimated breeding values (GEBVs) (Sverrisdóttir et al., 2018; Merrick et al., 2022). 3.2.3 Gene editing techniques: potential applications of CRISPR and other tools in sweet potato Gene editing techniques, such as CRISPR-Cas9, offer unprecedented precision in modifying specific genes associated with desirable traits. These tools can be used to introduce or knock out genes to enhance traits like disease resistance, drought tolerance, and nutritional quality. While gene editing is still in its early stages for sweet potatoes, its potential applications are vast. For example, CRISPR has been successfully used in other crops to improve traits rapidly and accurately, suggesting similar possibilities for sweet potatoes (Meiyalaghan et al., 2019). The integration of gene editing with other molecular breeding methods could further accelerate the development of superior sweet potato cultivars (Sandhu et al., 2022). 4 Case Study of Sweet Potato Breeding for Enhanced Yield 4.1 Selection and improvement of high-yield traits The selection and improvement of high-yield traits in sweet potato breeding programs have been pivotal in enhancing crop productivity. The high genetic variability present in sweet potato populations offers significant opportunities for genetic gains through selective breeding, the use of selection indexes, such as the one proposed by Mulamba & Mock, has been effective in identifying superior individuals for root production and dual-aptitude traits, as demonstrated by the evaluation of 95 accessions and two commercial cultivars, leading to the recommendation of specific clones for further testing (Vargas et al., 2020). Additionally, the assessment of genotype × environment interactions (G × E) and stability analysis has been crucial in identifying genotypes that not only yield high but also exhibit stability across diverse environments. This approach has been successfully applied in Nigeria, where genotypes G13, G11, and G14 were identified as promising candidates due to their high mean root yield and stability (Ebem et al., 2021). The evaluation of genetic parameters and the use of multi-trait selection indexes have facilitated the identification of genotypes with high genetic variability and potential for significant genetic advances, such as the CERAT31-01, CERAT21-02, and CERAT51-30 genotypes (Otoboni et al., 2020). These methodologies underscore the importance of integrating genetic variability, selection indexes, and stability analysis in breeding programs to achieve enhanced yield traits in sweet potato. 4.2 Case analysis: development of high-yield sweet potato varieties in Nigeria The development of high-yield sweet potato varieties in Nigeria has been a focal point of breeding programs aimed at improving productivity and food security. In a study conducted to evaluate the agronomic performance of sweet potato genotypes across different agro-ecological regions in Nigeria, significant genetic variability was observed among the genotypes, which is essential for effective crop development. For example, genotype PYT/12/074 exhibited the highest root yield in both the rainforest belt and the humid guinea savannah, highlighting its potential as a superior variety (Agbim et al., 2022). Another study focused on the evaluation of selected sweet potato landraces for high harvest index and root yield indices, identified accessions such as Kwara, Agege, and Buttermilk as high-yielding varieties suitable for inclusion in breeding programs (Nwankwo et al., 2018). The use of multi-trait selection indexes and stability analysis in multi-environmental evaluations has proven effective in selecting genotypes with superior agronomic performance and stability. The CropInd tool, facilitated the selection of the 0113-672COR variety for the Colombian Caribbean region (Figure 1), demonstrating the applicability of such methodologies in different contexts (Rosero et al., 2023). These case studies illustrate the successful application of advanced breeding techniques and the importance of selecting genotypes with high yield potential and stability to enhance sweet potato production in Nigeria. 5 Improvement of Sweet Potato Quality Traits 5.1 Breeding strategies for increasing starch content Enhancing the starch content in sweet potatoes is a critical objective for breeding programs aimed at improving the crop’s agronomic traits. One effective strategy involves the use of polyploid genome-wide association studies (GWAS) to identify genetic markers associated with high starch content. For instance, a study identified
RkJQdWJsaXNoZXIy MjQ4ODYzMg==