Triticeae Genomics and Genetics, 2024, Vol.15, No.4, 206-220 http://cropscipublisher.com/index.php/tgg 207 develop wheat varieties that are resilient, high-yielding, and capable of sustaining global food security in the face of evolving agricultural challenges. This research report will delve into the significance of genetic diversity in wheat improvement, the potential of synthetic wheat as a source of novel genetic variation, and the strategies to harness this potential for the development of superior wheat cultivars. 2 Creation of Synthetic Wheat 2.1 Methods of synthesizing wheat The creation of synthetic wheat involves the deliberate hybridization of different wheat species to reintroduce genetic diversity and desirable traits into modern wheat cultivars. This process typically involves crossing tetraploid wheat species, such as Triticum turgidum, with diploid wild relatives like Aegilops tauschii, to produce synthetic hexaploid wheat (SHW) (Mirzaghaderi et al., 2010; Ogbonnaya et al., 2013; Wan et al., 2023). The hybridization process can be complex and requires careful selection of parent species to ensure the desired genetic traits are incorporated. One common method involves making cross combinations between diverse genotypes of wheat and Aegilops species. For instance, crosses between emmer wheat (Triticum turgidumsubsp. dicoccum) and Aegilops tauschii have been used to create synthetic hexaploid lines (Mirzaghaderi et al., 2020). The resulting F1 hybrids are often unstable and require in vitro rescue of embryos to produce viable plants. These plants are then self-pollinated to produce stable F2 lines with the desired hexaploid genome (AABBDD) (Mirzaghaderi et al., 2020). Another approach is the "double top-cross" method, where one parent is a synthetic hexaploid wheat, and the other is an elite bread wheat variety. This method involves a two-phase selection process to introgress multiple genomic regions from the synthetic parent into the elite cultivar, enhancing yield potential and other agronomic traits (Hao et al., 2019). This strategy has been shown to be effective in developing high-yielding wheat varieties with improved genetic diversity. 2.2 Key genetic and phenotypic characteristics of synthetic wheat Synthetic wheat lines exhibit a range of genetic and phenotypic characteristics that make them valuable for wheat improvement. Genetically, synthetic wheats are more diverse than their elite counterparts, as they incorporate novel alleles from wild relatives that are not present in modern wheat varieties (Sehgal et al., 2015; Ali et al., 2022). This increased genetic diversity is crucial for enhancing traits such as disease resistance, abiotic stress tolerance, and yield potential. Phenotypically, synthetic wheats often display traits that are beneficial for breeding programs. For example, they may exhibit increased resistance to biotic stresses such as rusts, septoria, and fusarium head blight, as well as abiotic stresses like drought, heat, and salinity (Ogbonnaya et al., 2013; Li et al., 2014). These traits are particularly important for developing wheat varieties that can thrive in diverse and challenging environments. In addition to stress resistance, synthetic wheats can also contribute to improved grain quality and yield. Studies have shown that synthetic-derived lines can outperform elite parent varieties in terms of grain yield and other important agronomic traits (Dunckel et al., 2017; Bhatta et al., 2019). This is due to the introgression of favorable alleles from the synthetic parents, which enhance traits such as grain size, spike number, and overall plant vigor. 2.3 Case studies of successful synthetic wheat creation Several case studies highlight the successful creation and utilization of synthetic wheat for crop improvement. One notable example is the work conducted at the International Center for Maize and Wheat Improvement (CIMMYT), where primary synthetic bread wheats were produced by crossing diverse wild relatives with elite cultivars. Field trials demonstrated that synthetic-derived lines outperformed the elite parent Opata M85 in various environments, indicating the potential of synthetic wheats to contribute alleles that increase yield (Dunckel et al., 2017). Another successful case is the development of synthetic hexaploid wheat lines by crossing Triticum turgidumwith Aegilops tauschii. This approach has been used to create stable amphiploids with the AABBDD genome, which
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