Molecular Plant Breeding 2025, Vol.16, No.1, 55-62 http://genbreedpublisher.com/index.php/mpb 57 2.3 Impact on potato genetic improvement The advancements in genetic mapping technologies, particularly the integration of NGS and genomics, have had a profound impact on potato genetic improvement. These technologies have facilitated the rapid development of tightly linked DNA markers, which are crucial for marker-assisted selection (MAS) in breeding programs. The ability to accurately identify and select for desirable traits has accelerated the breeding process, leading to the development of potato varieties with improved yield, nutritional value, and stress tolerance (Hameed et al., 2018; Sahu et al., 2020). Moreover, the application of new breeding technologies such as CRISPR/Cas9 and TALENs has enabled the generation of transgene-free products, addressing consumer and regulatory concerns while enhancing the agronomic profile of potatoes. 3 Diverse Marker Types and Their Utility in Potato Breeding 3.1 Overview of marker types In potato breeding, various molecular markers are employed to facilitate the identification and selection of desirable traits. These markers include simple sequence repeats (SSRs), single nucleotide polymorphisms (SNPs), sequence-characterized amplified regions (SCARs), and kompetitive allele-specific PCR (KASP) markers. SSR markers are highly polymorphic and have been extensively used for genetic diversity studies and association mapping (Meng et al., 2021; Bhardwaj et al., 2023). SNP markers, on the other hand, offer high-throughput and dense genome coverage, making them suitable for genomic selection and QTL mapping (Massa et al., 2015). SCAR markers are particularly useful for tracking specific resistance genes, such as those conferring resistance to late blight. KASP markers provide a cost-effective and efficient platform for genotyping, especially when consolidated from various marker types. 3.2 Selection of marker types based on breeding objectives The choice of marker type in potato breeding largely depends on the specific breeding objectives. For instance, SSR markers are preferred for evaluating genetic diversity and population structure due to their high polymorphism and informativeness. When the goal is to rapidly develop tightly linked DNA markers for traits such as disease resistance, SNP markers identified through whole-genome resequencing and QTL-seq are highly effective (Caruana et al., 2019; Yamakawa et al., 2021). For early-stage screening of breeding populations, SCAR markers are advantageous as they can halve the workload by efficiently tracking resistance genes. KASP markers are ideal for integrating various marker types into a single platform, thus streamlining the genotyping process in commercial breeding programs (Meade et al., 2019). 3.3 Case studies of marker utility Several case studies highlight the practical applications of these markers in potato breeding. One study demonstrated the use of SCAR markers to track Rpi genes for late blight resistance, significantly reducing the screening workload in early breeding stages (Beketova et al., 2021). Another study utilized SSR markers to analyze genetic diversity and identify markers associated with late blight resistance, providing valuable tools for marker-assisted selection (MAS) (Figure 2) (Bhardwaj et al., 2023). The development of SNP markers through QTL-seq has been shown to facilitate the rapid identification of markers linked to important traits such as nematode resistance and anthocyanin content in storage roots. Additionally, the implementation of KASP markers has enabled the consolidation of various resistance markers into a single genotyping platform, enhancing the efficiency of MAS in commercial breeding programs. 4 Marker-Assisted Selection in Trait Improvement through MAS 4.1 MAS for disease resistance and agronomic traits Late blight, caused by Phytophthora infestans, is a significant threat to potato crops worldwide. Marker-assisted selection (MAS) has been effectively utilized to enhance resistance to this disease. For instance, the use of SCAR markers to track Rpi genes has shown promise in early-stage breeding programs, significantly reducing the workload by half when screening F1 offspring for late blight resistance (Beketova et al., 2021; Markel and Shih, 2021). SSR markers have been employed to evaluate genetic diversity and population structure, identifying specific markers associated with late blight resistance, which can be used in MAS breeding. SNP-based genetic
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