Cotton Genomics and Genetics 2024, Vol.15, No.2, 103-111 http://cropscipublisher.com/index.php/cgg 106 of heterozygotes, and genotype-based selection unaffected by environmental conditions. The main content highlights that MAS, facilitated by DNA marker technology and QTL mapping, significantly improves crop breeding efficiency. MAS reduces the need for extensive field trials, halves the breeding time, and allows precise selection of desirable traits, including complex and difficult-to-assess traits. This method also enables the identification and incorporation of beneficial alleles from wild relatives, enhancing crop phenotypes and introducing valuable genetic diversity. Figure 1 Marker-assisted selection in comparison with conventional breeding (Adopted from Kushanov et al., 2021) Image caption: P1 and P2-parental genotypes, F1-first generation hybrid, Fn-hybrid progeny obtained from first generation by self-pollination, and BCn-backcross generations (Adopted from Kushanov et al., 2021) 4.2 Marker-assisted selection (MAS) Marker-assisted selection (MAS) is a powerful tool that leverages cytogenetic markers to accelerate the breeding process by selecting plants with desirable traits at the DNA level rather than relying solely on phenotypic selection. This approach significantly shortens the breeding cycle and increases the precision of selecting superior genotypes. Studies such as Li et al. (2022) and Ijaz et al. (2019) demonstrate the application of MAS in improving fiber length and strength in Gossypium hirsutum, showcasing the efficiency of functional markers in breeding programs. Additionally, Hasan et al. (2021) discuss the broader applications of MAS in plant breeding, emphasizing its role in trait stacking, gene pyramiding, and multi-trait introgression. 4.3 Identifying and mapping disease resistance genes Cytogenetic markers are instrumental in identifying and mapping genes associated with disease resistance in cotton. By pinpointing the loci responsible for resistance to various pathogens, breeders can develop cotton varieties that are more resilient to diseases, thereby reducing yield losses and the need for chemical controls. The research by Zhao et al. (2022) provides insights into the genetic basis of Fusarium wilt resistance in Gossypium barbadense, while Li et al. (2018) and Liu et al. (2022) highlight the identification of quantitative trait loci (QTLs) linked to disease resistance, facilitating the incorporation of these traits into breeding programs through MAS.
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