Molecular Plant Breeding 2024, Vol.15, No.6, 379-390 http://genbreedpublisher.com/index.php/mpb 381 oxidative stress, and low temperature, without causing phenotypic defects. This genetic modification leads to increased glycine betaine accumulation, which helps maintain cell membrane integrity and reduces reactive oxygen species (ROS) production under stress conditions (Fan et al., 2012). Moreover, the use of crop wild relatives (CWRs) has been identified as a valuable approach to introduce genetic diversity and improve abiotic stress tolerance in sweet potato (Kapazoglou et al., 2023). 3.3 Nutritional quality and biofortification Improving the nutritional quality of sweet potato is a key objective for breeding programs, particularly in regions where the crop is a staple food. Biofortification efforts have focused on increasing the content of essential nutrients such as carotene, vitamins, and minerals. For example, genetic variability in carotene content among sweet potato genotypes has been documented, with significant associations between carotene content and other agronomic traits like vine length and number of leaves per plant (Solankey et al., 2015). Advances in genomic tools and technologies have facilitated the identification and transfer of genomic regions responsible for desirable nutritional traits, accelerating the development of biofortified sweet potato varieties (Figure 1) (Medina-Lozano and Díaz, 2022). These efforts are crucial for addressing micronutrient deficiencies and improving the overall health benefits of sweet potato consumption. Figure 1 Schematic representation of three modern biotechnology techniques to introduce allelic variants of interest in a recipient organism: (A) transgeneis; (B) cisgenesis; and (C) intragenesis (Adopted from Medina-Lozano and Díaz, 2022) 4 Techniques and Technologies for Breeding 4.1 Conventional breeding approaches Conventional breeding approaches in sweet potato involve the selection and cross-breeding of plants with desirable traits to produce improved cultivars. This method relies heavily on phenotypic selection and has been the cornerstone of crop improvement for centuries. The process involves selecting parent plants with favorable characteristics, cross-pollinating them, and then selecting the best offspring over several generations. This approach, while effective, is time-consuming and labor-intensive, often requiring many years to develop a new cultivar with the desired traits.
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