Bioscience Methods 2025, Vol.16, No.1, 1-10 http://bioscipublisher.com/index.php/bm 6 development of sweet potato varieties with enhanced abiotic stress tolerance. By combining the strengths of genetic engineering, CRISPR technology, and marker-assisted selection, it is possible to achieve more robust and resilient crops. For example, the overexpression of transcription factors such as IbBBX24 and IbTOE3 has been shown to enhance ROS scavenging and improve tolerance to salt and drought stresses in sweet potato (Zhang et al., 2021). Similarly, the manipulation of genes involved in inositol biosynthesis and ABA signaling pathways has demonstrated significant improvements in stress tolerance and resistance to biotic stresses (Zhai et al., 2016). These integrated approaches not only stabilize yield production under unfavorable conditions but also provide novel germplasm for sweet potato cultivation on marginal lands (Anwar and Kim, 2020). 6 Case Studies 6.1 Drought-resistant sweet potato varieties Several studies have identified key genetic modifications that enhance drought resistance in sweet potato. For instance, the overexpression of the IbBBX24 and IbPRX17 genes has been shown to significantly improve drought tolerance by enhancing reactive oxygen species (ROS) scavenging capabilities (Zhang et al., 2021). Similarly, the IbMIPS1 gene, which is involved in myo-inositol biosynthesis, has been found to enhance drought tolerance by upregulating stress response pathways and increasing the accumulation of protective metabolites such as proline and trehalose. Another gene, IbC3H18, a non-tandem CCCH-type zinc-finger protein, has also been reported to increase drought tolerance by regulating the expression of stress-responsive genes and enhancing ROS scavenging. Additionally, the IbSnRK1 gene has been shown to confer drought tolerance by activating the ROS scavenging system and controlling stomatal closure via the ABA signaling pathway (Ren et al., 2020). 6.2 Salinity tolerance in sweet potato Salinity stress is another major abiotic factor limiting sweet potato productivity. The overexpression of the IbBBX24 and IbPRX17 genes not only improves drought tolerance but also enhances salinity tolerance by reducing H2O2 accumulation and increasing peroxidase activity (Figure 3). The IbMIPS1 gene has also been shown to confer salinity tolerance by upregulating genes involved in inositol biosynthesis and ABA signaling pathways, leading to increased accumulation of protective metabolites and reduced Na+ content. The IbC3H18 gene enhances salinity tolerance by regulating ion transport pathways and increasing ROS scavenging (Zhang et al., 2019). Furthermore, the overexpression of the AtNHX1 gene, which encodes a vacuolar Na+/H+ antiporter, has been demonstrated to improve salinity tolerance by enhancing Na+ compartmentalization into vacuoles, thereby maintaining high K+/Na+ ratios and reducing cell damage. 6.3 Results and key learnings from case studies The case studies on drought and salinity tolerance in sweet potato reveal several key mechanisms that contribute to enhanced abiotic stress tolerance. One common theme is the importance of ROS scavenging systems. Genes such as IbBBX24, IbPRX17, IbC3H18, and IbSnRK1 all play crucial roles in enhancing the plant's ability to scavenge ROS, thereby reducing oxidative damage under stress conditions. Another critical mechanism is the regulation of ion transport and compartmentalization, as demonstrated by the AtNHX1 gene, which helps maintain ionic balance and reduce toxicity under salinity stress (Fan et al., 2015). Additionally, the accumulation of protective metabolites such as proline, trehalose, and inositol is a recurring strategy for enhancing stress tolerance, as seen with the IbMIPS1 gene (Zhai et al., 2016). These findings highlight the potential of genetic engineering to develop sweet potato varieties with improved tolerance to multiple abiotic stresses (Zhao et al., 2022). By targeting key genes involved in ROS scavenging, ion transport, and metabolite accumulation, it is possible to create crops that can withstand harsh environmental conditions, thereby ensuring stable yield production. 7 Challenges and Future Directions 7.1 Limitations in current breeding programs Current breeding programs for sweet potato face several limitations in developing abiotic stress-tolerant varieties. Traditional breeding methods have primarily focused on traits such as yield and disease resistance, often neglecting abiotic stress tolerance (Kikuchi et al., 2015). The polygenic nature of stress tolerance traits
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