Triticeae Genomics and Genetics, 2024, Vol.15, No.3, 152-161 http://cropscipublisher.com/index.php/tgg 156 4.3 Genomic tools and techniques Marker-assisted selection (MAS) has revolutionized the process of introgressing exotic traits into wheat. By utilizing molecular markers linked to desirable traits, breeders can efficiently select for these traits in the early generations of breeding programs. For example, the identification of quantitative trait loci (QTLs) associated with abiotic stress tolerance has facilitated the use of MAS in breeding programs aimed at improving stress resilience in major cereals, including wheat (Raj and Nadarajah, 2022). Genomic selection (GS) is another powerful tool that leverages genome-wide marker information to predict the breeding value of individuals. This approach has been successfully applied in wheat breeding to enhance the selection process for complex traits such as yield and stress tolerance. The integration of GS with traditional breeding methods has the potential to accelerate the development of improved wheat varieties with introgressed exotic traits (Hao et al., 2020) (Figure 2). Figure 2 The Double Top-Cross (DTC) and Two-Phase Selection (2PS) Strategies for Managing Introgression into Elite Germplasm from a Synthetic Hexaploid Wheat (SHW) (Adapted from Hao et al., 2020) Image caption: The DTC populations maintain an average of 12.5% of the nuclear genome of the SHW parent. The first selection phase, conducted during the F2 and F3 generations, aims to eliminate severe agronomic defects. The second phase, starting from the F4 generation onwards, focuses on yield improvement. Notably, the cultivars Shumai 969 and Shumai 830 were developed using this breeding strategy (Adapted from Hao et al., 2020) Hao et al. (2020) demonstrates the double top-cross (DTC) and two-phase selection (2PS) strategies for introgressing synthetic wheat (SHW) into elite germplasm. The DTC strategy involves sequential crosses with three elite varieties, retaining 12.5% of SHW nuclear DNA. The 2PS strategy is implemented in two phases: the first phase (F2 and F3 generations) eliminates undesirable agronomic traits like tough glumes, late maturity, tall stature, and yellow rust susceptibility. The second phase (F4 onwards) focuses on improving yield. This method has successfully produced new wheat cultivars such as Shumai 580, Shumai 969, and Shumai 830, with a fourth, Shumai 114, expected soon. The effectiveness of the DTC-2PS strategy is evident in producing high-yielding, agronomically superior varieties with desirable traits from SHW, showcasing its potential for wheat breeding programs. CRISPR and other gene-editing technologies offer unprecedented precision in the manipulation of genetic material. These tools have been employed to introduce specific genes or alleles from exotic germplasm into wheat, thereby enhancing its genetic diversity and adaptive potential. The use of CRISPR/Cas9 system, for instance, has enabled the targeted modification of genes associated with abiotic stress tolerance, providing new avenues for wheat improvement (Raj and Nadarajah, 2022).
RkJQdWJsaXNoZXIy MjQ4ODYzNQ==