Triticeae Genomics and Genetics, 2024, Vol.15, No.3, 152-161 http://cropscipublisher.com/index.php/tgg 158 enhance drought tolerance, disease resistance, and overall yield (Afzal et al., 2019; Aberkane et al., 2020; Zhou et al., 2021). The creation of synthetic octoploid wheat pools and the development of multiple synthetic derivatives (MSD) have provided robust platforms for exploring and harnessing genetic diversity (Gorafi et al., 2018 Zhou et al., 2021). The success of these synthetic wheats in breeding programs underscores their value in addressing global food security challenges, especially in the face of climate change (Hao et al., 2019; Rosyara et al., 2019; Aberkane et al., 2020). 6.3 Integrating exotic germplasm into modern breeding programs Integrating exotic germplasm into modern wheat breeding programs requires strategic approaches to overcome challenges such as linkage drag and adaptation issues. The double top-cross (DTC) strategy and two-phase selection procedures have proven effective in incorporating synthetic hexaploid wheat into elite lines, resulting in high-yielding varieties with enhanced genetic diversity (Hao et al., 2019). The use of advanced genomic tools, such as SNP-GWAS and haplotype-GWAS, has facilitated the identification of key genomic regions associated with desirable traits, enabling more precise breeding efforts (Afzal et al., 2019; Balla et al., 2022). Additionally, the establishment of core germplasm collections and the systematic evaluation of exotic lines under diverse environmental conditions are critical for maximizing the benefits of exotic germplasm in breeding programs (Gorafi et al., 2018; Zhou et al., 2021; Balla et al., 2022). In conclusion, the future of wheat improvement lies in the strategic utilization of exotic germplasm, particularly through the development and integration of synthetic wheats. Continued advancements in genomic technologies and breeding strategies will be essential in harnessing the full potential of these genetic resources to meet the growing demands for food security and climate resilience. 7 Concluding Remarks The research on harnessing genetic diversity for wheat improvement using exotic germplasm has yielded several significant findings. The use of non-denaturing fluorescence in situ hybridization (ND-FISH) has revealed extensive chromosomal polymorphisms and genetic diversity among wheat lines, particularly highlighting the polymorphism of the B-genome over the A- and D-genomes. Studies have identified substantial genetic variability and diversity in wheat germplasm, which is crucial for breeding programs aimed at improving yield and adaptation to environmental fluctuations. A haplotype-based approach has been developed to enhance the precision of wheat breeding, enabling the identification of novel haplotypes with potential for trait improvement. The introgression of Aegilops tauschii genome into wheat has been shown to enrich the wheat germplasm pool and improve breeding efficiency. Additionally, wild emmer wheat diversity has been exploited to improve wheat's heat stress adaptation, identifying several quantitative trait loci (QTL) associated with heat tolerance. The development of nested association mapping (NAM) populations has provided a valuable genetic resource for breeding under dry and hot climates. Advances in genomics and phenomics have facilitated trait discovery in polyploid wheat, overcoming previous challenges related to its large genome and limited genetic diversity. Genome-wide analyses have identified adaptive traits in synthetic-derived wheats, highlighting the role of crop-wild introgressions in improving drought tolerance. Exome sequencing has underscored the significant contribution of wild-relative introgression to the adaptive diversity of modern bread wheat. Finally, the integration of exotic material has been shown to alleviate the genetic bottleneck in the D genome, enhancing photosynthetic capacity and overall genetic diversity. The findings from these studies have profound implications for wheat improvement. The identification of extensive genetic diversity and specific chromosomal polymorphisms provides a rich resource for breeding programs aimed at enhancing wheat yield, stress tolerance, and adaptability to changing environmental conditions. The development of haplotype-based approaches and the introgression of genomes from wild relatives like Aegilops tauschii and wild emmer wheat offer new avenues for incorporating beneficial traits into elite wheat cultivars, thereby improving their agronomic performance. The creation of NAM populations and the application of advanced genomic and phenomic techniques enable more precise and efficient breeding strategies, addressing the challenges posed by climate change and the need for sustainable food production. The identification of
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