Triticeae Genomics and Genetics, 2024, Vol.15, No.4, 206-220 http://cropscipublisher.com/index.php/tgg 210 Introgression lines developed using synthetic octaploid wheat (Aegilops tauschii×hexaploid wheat) as donors have shown significant phenotypic variance and improved agronomic traits compared to the recurrent parent lines. This approach has led to the identification of quantitative trait loci (QTLs) for important traits such as thousand kernel weight, spike length, and plant height, further demonstrating the utility of synthetic wheats in breeding (Zhang et al., 2018). 3.3 Identification of unique genetic traits The unique genetic traits introduced by synthetic wheat lines have been extensively studied and documented. These traits include enhanced yield potential, improved stress tolerance, and disease resistance. For instance, synthetic-derived lines have been shown to outperform elite parent lines in various environmental conditions, including irrigated, heat, and drought-stressed environments (Dunckel et al., 2017). This indicates that synthetic wheats contribute alleles that enhance yield and adaptability. Genomic analyses have identified specific genes and genomic regions associated with these beneficial traits. For example, a study identified 89 selective sweeps in synthetic-derived wheats, with key selections co-localizing with functional genes related to earliness, grain size, drought tolerance, and vernalization (Afzal et al., 2019). These findings highlight the potential of synthetic wheats to introduce new alleles that can be harnessed for wheat improvement. The use of synthetic hexaploid wheat has led to the development of high-yielding wheat varieties with enhanced disease resistance and stress tolerance. For instance, primary SHW lines have been used to develop new wheat varieties with more spikes per plant, larger grains, and higher grain yield potential (Li et al., 2014). These varieties have shown significant improvements in grain yields under both natural and artificial selection conditions. Overall, the genetic foundation of synthetic wheat lies in its ability to reintroduce and harness genetic diversity from wild relatives, thereby providing a rich source of alleles for improving modern wheat cultivars. Through genomic analyses and targeted introgressions, synthetic wheats have proven to be invaluable in the quest for higher-yielding, more resilient wheat varieties. 4 Benefits of Synthetic Wheat in Breeding Programs 4.1 Enhanced disease and pest resistance Synthetic hexaploid wheat (SHW) has been instrumental in introducing novel genetic diversity into modern wheat varieties, significantly enhancing their resistance to various diseases and pests. The primary SHW lines, derived from the tetraploid wheat Triticum turgidum and the wild ancestor Aegilops tauschii, have been shown to contribute elite characters such as disease resistance to new wheat varieties. These characters include resistance to rusts, septoria, barley yellow dwarf virus (BYDV), crown rot, tan spot, spot blotch, nematodes, powdery mildew, and fusarium head blight (Ogbonnaya et al., 2013; Li et al., 2014). The introgression of these resistance traits from SHW into hexaploid wheat has led to the development of wheat varieties that are more resilient to biotic stresses, thereby reducing the reliance on chemical pesticides and contributing to sustainable agricultural practices (Ogbonnaya et al., 2013; Li et al., 2014). 4.2 Improved abiotic stress tolerance (drought, heat, salinity) Abiotic stress tolerance is a critical trait for wheat, especially in the context of climate change and the increasing frequency of extreme weather events. SHW has been a valuable resource for enhancing wheat's tolerance to abiotic stresses such as drought, heat, and salinity. The genetic diversity present in SHW includes alleles that confer improved tolerance to these stresses, which have been successfully introgressed into modern wheat varieties (Figure 3) (Sehgal et al., 2015; Trono and Pecchion, 2022). For instance, synthetic-derived lines have shown significant improvements in drought and heat tolerance, with novel alleles identified for these traits from landraces and SHW (Sehgal et al., 2015; Jafarzadeh et al., 2016). Additionally, SHW has been used to develop wheat varieties with enhanced tolerance to waterlogging and soil micronutrient imbalances, further broadening the environmental adaptability of wheat (Trethowan and Mujeeb-Kazi, 2016). The use of advanced breeding techniques, such as genomic selection and marker-assisted selection, has accelerated the incorporation of these
RkJQdWJsaXNoZXIy MjQ4ODYzNQ==