Molecular Plant Breeding 2025, Vol.16, No.1, 55-62 http://genbreedpublisher.com/index.php/mpb 58 maps have also been developed to locate QTLs contributing to late blight resistance, enabling the introgression of multiple resistance sources through MAS. PCR-based assays for Rpi-blb1 and Rpi-bt1 genes have been validated to distinguish between resistant and susceptible progeny, further supporting the utility of MAS in breeding for late blight resistance (Chen et al., 2017). Figure 2 Boxplots representing variations for late blight resistance in four subpopulations generated from the diversity panel of 353 potato accessions through structure software based on the 25 SSR markers: (a) Pop-1; (b) Pop-2; (c) Pop-3; (d) Pop-4 (Adopted from Bhardwaj et al., 2023) Potato virus Y (PVY) is another major concern for potato breeders. MAS has been applied to develop PVY-resistant cultivars by identifying and utilizing DNA markers linked to resistance genes from different species. For example, markers such as RYSC3, Ry364, and RAPD38-530 have been used to genotype breeding lines, facilitating the selection of lines with combined resistance genes from different species (Voronkova et al., 2020). In Australia, the RYSC3, M45, and STM0003 markers have been validated for their effectiveness in identifying PVY-resistant cultivars, demonstrating the potential of these markers in MAS for PVY resistance (Slater et al., 2020). MAS has also been employed to improve agronomic traits such as drought tolerance. The development of functional markers (FMs) associated with specific phenotypic traits allows for precise selection in breeding programs. These markers facilitate the direct selection of genes linked to desirable traits, thereby increasing the efficiency of breeding for complex traits like drought tolerance. The integration of MAS with advanced genomic tools has enabled the identification of QTLs associated with agronomic traits, further enhancing the potential for improving these traits through targeted breeding strategies (Kadirvel et al., 2015). 4.2 Enhancements in root and tuber quality MAS has been instrumental in improving root and tuber quality in potatoes. By identifying markers linked to quality traits, breeders can select for desirable characteristics such as tuber size, shape, and nutritional content. The use of genome-scanning marker platforms like PotatoMASH allows for the efficient survey of genetic variation throughout the potato genome, facilitating the selection of superior lines with enhanced tuber quality (Leyva-Pérez et al., 2022). The application of MAS in this context ensures that breeding programs can rapidly and accurately develop cultivars with improved root and tuber quality. 4.3 MAS strategies for polygenic traits Polygenic traits, controlled by multiple genes, present a challenge for traditional breeding methods. However, MAS strategies such as marker-assisted recurrent selection (MARS) and genome-wide association studies (GWAS) have shown potential in improving these complex traits. MARS allows for the accumulation of favorable alleles over successive generations, while GWAS enables the identification of QTLs associated with polygenic traits (Hasan et al., 2021; Huang and Hong, 2024). These strategies, combined with the use of functional markers, provide a robust framework for the enhancement of polygenic traits in potato breeding programs (Salgotra and Stewart, 2020).
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