Genomics and Applied Biology 2024, Vol.15, No.6, 307-319 http://bioscipublisher.com/index.php/gab 310 which often require time-consuming phenotypic assessments that are influenced by environmental factors (Norman et al., 2022). Furthermore, advancements in genomic resources for yam, such as high-quality reference genomes and comprehensive marker datasets, have made the integration of GS into breeding projects increasingly feasible and cost-effective. The reduction in genotyping costs, combined with improved computational tools, enables breeders to incorporate GS into yam breeding strategies, enhancing the overall efficiency, responsiveness, and adaptability of breeding programs to meet evolving agricultural demands (Crossa et al., 2017). The adoption of GS in yam breeding also holds the potential to address long-standing challenges associated with genotype-by-environment interactions by allowing breeders to assess genetic potential across diverse environments without requiring extensive multi-location trials. This shift towards genomics-driven breeding represents a viable solution for accelerating yam crop improvement and achieving stable, high-performance varieties capable of meeting future agricultural needs more effectively. 4 Development and Utilization of Genomic Resources 4.1 Methods for establishing genomic resources for yam The establishment of genomic resources for yam has greatly benefited from advancements in next-generation sequencing (NGS) technologies, which have provided critical genetic data to support breeding and improvement efforts. Techniques such as genotyping-by-sequencing (GBS), expressed sequence tag (EST) sequencing, and whole-genome sequencing (WGS) are among the primary NGS approaches used to generate detailed genomic information for yam. Genotyping-by-sequencing, for example, has proven effective in producing high-density single nucleotide polymorphism (SNP) markers across yam genomes. These SNPs are invaluable for accurately mapping complex traits, including yield, disease resistance, and environmental adaptability, which are essential for developing improved yam varieties. By identifying specific genomic regions associated with these traits, breeders can make informed selections to accelerate yam breeding cycles and enhance genetic gains (Saski et al., 2015). In addition to SNP markers, microsatellite markers, or simple sequence repeats (SSRs), have been developed for yam and offer further benefits for breeding programs. SSRs are highly polymorphic, which allows them to reveal substantial genetic diversity within and across yam species. This diversity is crucial for yam breeding, as it provides the genetic variation necessary for adaptability and resilience under changing environmental conditions. Moreover, SSR markers are known for their cross-species transferability, enabling their application across various yam species. This cross-applicability is especially advantageous for breeding programs, as it allows breeders to efficiently analyze genetic diversity and track desirable traits across different breeding populations, making marker-assisted selection (MAS) both feasible and effective (Diouf et al., 2023). These genomic resources not only streamline traditional breeding methods but also facilitate advanced breeding techniques like genome-wide association studies (GWAS) and genomic selection (GS). With access to comprehensive genomic data, breeders can better understand the genetic underpinnings of important traits and develop varieties tailored to specific agricultural challenges. As the cost of NGS continues to decrease, the expansion of these genomic resources will further enhance yam breeding programs, helping to create high-yielding, resilient yam varieties that can meet the demands of future food security and sustainability. 4.2 Applications of whole-genome profiling and marker development Whole-genome profiling has become a cornerstone in modern yam breeding, enabling efficient marker discovery, detailed genetic diversity analysis, and quantitative trait locus (QTL) mapping for complex, multi-gene traits. Single nucleotide polymorphisms (SNPs) and simple sequence repeat (SSR) markers, generated through whole-genome sequencing (WGS) and genotyping-by-sequencing (GBS), allow for high-resolution trait mapping. This detailed genetic information is instrumental for trait association studies, supporting breeders in identifying the genetic basis of desirable traits such as disease resistance, yield, and environmental adaptability. By using these markers within genomic selection models, breeders can assess and predict the genetic potential of yam plants early in the breeding cycle, accelerating the development of improved varieties (Tamiru et al., 2017).
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