Molecular Plant Breeding 2025, Vol.16, No.1, 73-81 http://genbreedpublisher.com/index.php/mpb 78 6 Impact of Molecular Breeding on Crop Performance 6.1 Improved yield and water use efficiency in new varieties Molecular breeding has significantly enhanced the yield and water use efficiency (WUE) of sweet potato varieties under drought conditions. By employing advanced genetic tools, researchers have been able to identify and incorporate drought-tolerant traits into new cultivars. For instance, the study of physiological and biochemical features has been crucial in selecting genotypes that maintain high yields despite water stress (Lee et al., 2015). The use of next-generation sequencing (NGS) and genome-wide association studies (GWAS) has facilitated the identification of key genetic markers associated with drought tolerance, thereby accelerating the breeding process. These molecular techniques have led to the development of sweet potato varieties that exhibit improved WUE, which is essential for maintaining productivity in arid and semi-arid regions (Gervais et al., 2021). 6.2 Enhanced root architecture for drought adaptation One of the critical factors in drought resistance is the root architecture of the plant. Molecular breeding has enabled the modification of root traits to enhance water uptake and retention. For example, the expression of the DEEPER ROOTING 1 (DRO1) gene in sweet potato has been shown to alter root architecture, resulting in increased lateral root number and improved drought tolerance (Sun et al., 2022). Comparative transcriptome analysis has also revealed that deep-rooting genotypes exhibit a more robust response to drought stress, with significant changes in gene expression related to root cell elongation and division. These modifications in root architecture not only improve the plant's ability to access water from deeper soil layers but also contribute to overall drought resilience (Ponce et al., 2022). 6.3 Comparison with conventional breeding methods Molecular breeding offers several advantages over conventional breeding methods, particularly in the context of developing drought-resistant sweet potato varieties. Traditional breeding relies on phenotypic selection, which can be time-consuming and less precise. In contrast, molecular breeding utilizes genetic markers and advanced biotechnological tools to identify and incorporate desirable traits more efficiently (Sapakhova et al., 2023). Studies have shown that molecular breeding can significantly reduce the time required to develop new cultivars while also increasing the accuracy of trait selection (Saidi and Hajibarat, 2020). Moreover, the integration of high-throughput phenotyping platforms with molecular techniques allows for the precise screening and pyramiding of drought-related genes, which is less feasible with conventional methods (Obidiegwu et al., 2015). Molecular breeding represents a more effective and efficient approach to developing drought-resistant sweet potato varieties, ensuring better crop performance under challenging environmental conditions. 7 Breeding Strategies for Drought-Resistant Varieties 7.1 Crossbreeding and hybridization strategies Crossbreeding and hybridization are fundamental strategies in developing drought-resistant sweet potato varieties. These methods involve the selection and crossing of parent plants with desirable traits to produce offspring that exhibit improved drought tolerance and high yield potential. The study of physiological and biochemical features of certain sweet potato varieties is crucial for implementing effective drought resistance measures (Aslam et al., 2022). By understanding the genetic basis of drought tolerance, breeders can select and improve genotypes adapted to specific growing conditions, making the creation of drought-resistant varieties more cost-effective for smallholder farmers (Sapakhova et al., 2023). 7.2 Backcrossing with elite varieties Backcrossing is a breeding method where a hybrid organism is crossed with one of its parents or an organism genetically similar to its parent. This technique is used to introduce or maintain specific desirable traits, such as drought resistance, in elite varieties. For instance, marker-assisted backcross breeding has been successfully applied in rice to improve multiple biotic and abiotic stress tolerances, including drought, by introgressing specific genes and QTLs into elite varieties (Moon et al., 2018; Ramayya et al., 2021). This approach can be adapted for sweet potato breeding to enhance drought resistance while maintaining high yield and other agronomically important traits.
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