Triticeae Genomics and Genetics, 2024, Vol.15, No.2, 100-110 http://cropscipublisher.com/index.php/tgg 102 (Alvarez and Guzmán, 2018). The development of high-throughput genotyping arrays and improved methods of gene discovery have further facilitated the identification of useful genetic variations in wild relatives, which can be integrated into wheat breeding programs (Rasheed et al., 2018). 3.2 Cytogenetic barriers and solutions Cytogenetic barriers, such as chromosome elimination and non-disjunction, often pose significant challenges in wide hybridization. For example, in crosses between wheat and pearl millet, non-wheat chromosomes are frequently eliminated during embryogenesis, leading to hybrid instability (Ishii et al., 2010). However, innovative approaches have been developed to overcome these barriers. The creation of stable amphiploids and the strategic use of known genes have shown promise in developing perennial grain crops that combine the desirable traits of both parents (Curwen-McAdams and Jones, 2017). Moreover, the development of compensating wheat/barley Robertsonian translocation lines has successfully transferred favorable traits, such as salt tolerance and elevated β-glucan content, into a stable genetic background (Türkösi et al., 2018). 3.3 Molecular techniques for enhancing hybridization Advances in molecular techniques have significantly enhanced the efficiency of wide hybridization. Genomic in situ hybridization (GISH) and fluorescence in situ hybridization (FISH) are powerful tools for tracing and identifying wheat and non-wheat chromatin in hybrid embryos, facilitating the monitoring of chromosome dynamics and stability (Türkösi et al., 2018). Additionally, the integration of genomics-assisted selection and gene editing technologies has accelerated the exploitation of exotic genes, increasing the rate of genetic gain in wheat breeding programs (Rasheed et al., 2018). These molecular techniques, coupled with phenotypic recurrent selection and genome-wide prediction approaches, have shown potential in improving traits such as anther extrusion and hybrid seed set, which are critical for hybrid wheat breeding (Boeven et al., 2016; Boeven et al., 2018). Wide hybridization offers a valuable strategy for wheat genetic improvement by introducing new genetic diversity and desirable traits from wild and distantly related species. Overcoming genetic and cytogenetic barriers through advanced molecular techniques and strategic breeding approaches can significantly enhance the success and stability of wide hybrids, contributing to the development of improved wheat cultivars with enhanced quality, stress resistance, and yield potential. 4 Contributions to Wheat Breeding 4.1 Introduction of novel traits Wide hybridization has played a crucial role in introducing novel traits into wheat, significantly enhancing its genetic diversity. For instance, the hybridization between wheat and tall wheatgrass (Thinopyrum ponticum) has led to the development of wheat cultivars such as Xiaoyan 4, Xiaoyan 5, Xiaoyan 6, Xiaoyan 54, Xiaoyan 60, and Xiaoyan 81, which exhibit multiple disease resistances and adaptability to various environments (Li et al., 2015). Additionally, the utilization of wild relatives of wheat has provided valuable sources of allelic diversity, contributing to the introduction of novel traits such as resistance to stripe rust and Karnal bunt (Shafqat et al., 2021). 4.2 Improvement of disease resistance Wide hybridization has been instrumental in improving disease resistance in wheat. The introgression of resistance genes from wild relatives has significantly enhanced wheat's ability to withstand various diseases. For example, resistance has been successfully introgressed from at least 52 species from 13 genera, demonstrating the remarkable plasticity of the wheat genome (Wulff and Moscou, 2014). Moreover, the development of wheat-Thinopyrum bessarabicum genetic stock has provided novel sources of resistance to stripe rust and Karnal bunt, which are critical for sustainable crop production (Shafqat et al., 2021). The Xiaoyan series of wheat cultivars also exhibit multiple disease resistances, likely derived from tall wheatgrass (Li et al., 2015). 4.3 Enhancement of abiotic stress tolerance Abiotic stress tolerance is another area where wide hybridization has made significant contributions. The introduction of genetic diversity from wild relatives has enhanced wheat's tolerance to various abiotic stresses
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