Triticeae Genomics and Genetics, 2024, Vol.15, No.4, 206-220 http://cropscipublisher.com/index.php/tgg 211 beneficial traits into elite wheat cultivars, ensuring high yields under stress-prone conditions (Dunckel et al., 2017; Trono and Pecchion, 2022). Figure 3 Schematic representation of the signalling pathway leading to the plant response to abiotic stresses (Adopted from Trono and Pecchion, 2022) Image caption: Specific receptors in the plasma membrane perceive the external stress signal and transmit the signal intracellularly through phytohormones and secondary messengers, such as calcium (Ca2+) and reactive oxygen species (ROS). The second messengers activate different classes of protein kinases, including mitogen-activated protein kinase (MAPK) cascade, calcium-dependent protein kinases (CDPKs), and calcineurin-B-like proteins-interacting protein kinases (CIPKs), and protein phosphatases, such as protein tyrosine phosphatases/dual-specificity phosphatases (PTPs/DSPs), protein phosphatases 2C (PP2Cs), and serine/threonine-specific protein phosphatases (PPPs). Subsequently, the protein kinases and phosphatases catalyze the phosphorylation/dephosphorylation of transcription factors, including APETALA2/ethylene response element-binding factors (AP2/ERF), the large NAC family, basic leucine zipper (bZIP), WRKY, and MYB. These finally regulate the expression of abiotic stress-responsive genes encoding heat shock proteins (HSPs) and other chaperones, late embryogenesis abundant (LEA) proteins, enzymes involved in the biosynthesis of osmolytes, antioxidant enzymes and enzymes involved in the biosynthesis of small antioxidant molecules, aquaporins and ion transporters, which contribute to the tolerance of wheat to abiotic stresses (Adopted from Trono and Pecchion, 2022) 4.3 Yield improvement and quality traits One of the most significant benefits of incorporating SHW into breeding programs is the potential for yield improvement and the enhancement of quality traits. SHW has been shown to contribute to higher grain yields through the introduction of favorable alleles that increase the number of spikes per plant, grains per spike, and grain size (Li et al., 2014; Jafarzadeh et al., 2016; Trethowan and Mujeeb-Kazi, 2016). For example, yield trials conducted under various environmental conditions, including irrigated, drought, and heat-stress conditions, have demonstrated that synthetic-derived lines often outperform their recurrent parents in terms of yield. The genetic diversity from SHW not only enhances yield potential but also improves other agronomic traits such as kernel weight, biomass production, and photosynthetic efficiency (Blanco et al., 2001; Merchuk-Ovnat et al., 2016). Moreover, SHW has been utilized to improve grain quality traits, including protein content and gluten strength, which are essential for bread-making and other end-uses5. The introgression of novel alleles from SHW has led to the development of wheat varieties with superior quality traits, meeting the demands of both producers and consumers (Ogbonnaya et al., 2013). The combination of yield improvement and enhanced quality traits makes SHW a valuable resource for breeding programs aimed at developing high-performing wheat varieties that can thrive in diverse environments and meet the growing global demand for wheat (Ogbonnaya et al., 2013; Li et al., 2014; Trethowan and Mujeeb-Kazi, 2016). In summary, the incorporation of synthetic wheat into breeding programs offers numerous benefits, including enhanced disease and pest resistance, improved abiotic stress tolerance, and significant yield and quality trait
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