Molecular Plant Breeding 2024, Vol.15, No.6, 417-428 http://genbreedpublisher.com/index.php/mpb 419 Figure 1 Manhattan plots for thousand grain weight (TGW) and grain yield per plant (GYP) under normal and heat stress conditions (Adapted from Ahmed et al., 2022a) Image caption: The figure shows the genome-wide association study (GWAS) results for Thousand Grain Weight (TGW) and Grain Yield per Plant (GYP) under normal conditions (A, C) and heat stress conditions (B, D). The X-axis represents the wheat chromosome numbers, while the Y-axis indicates the -log10(p) values of significant SNP (Single Nucleotide Polymorphism) loci. The threshold line is used to identify significant genomic regions associated with yield traits (Adapted from Ahmed et al., 2022a) 2.3 Molecular improvement of high-yield germplasm The advent of gene editing technologies, particularly CRISPR-Cas9, has revolutionized the molecular improvement of high-yield germplasm in wheat. CRISPR-Cas9 allows for precise modifications of specific genes associated with yield traits, thereby enabling the development of wheat varieties with enhanced yield potential. Recent studies have demonstrated the potential of CRISPR-Cas9 in fine-tuning the expression of genes controlling yield and stress tolerance traits, thereby improving wheat productivity under various environmental conditions (Khadka et al., 2020a). For instance, the use of CRISPR-Cas9 to edit genes involved in drought tolerance has shown promising results in enhancing wheat yield under water-deficit conditions (Dwivedi et al., 2017). Moreover, the integration of CRISPR-Cas9 with other genomic tools, such as GWAS and QTL mapping, has further enhanced the efficiency of molecular breeding. This integrated approach allows for the identification and targeted modification of key genes associated with yield traits, thereby accelerating the development of high-yielding wheat varieties. For example, the identification of SNPs associated with heat tolerance and their subsequent editing using CRISPR-Cas9 has led to the development of wheat genotypes with improved yield under heat stress (Sall et al., 2023). The continued advancement of gene editing technologies and their application in wheat breeding holds great promise for achieving significant yield gains and ensuring food security in the face of climate change (Dwivedi et al., 2017; Khadka et al., 2020a). 3 Innovation and Utilization of Wheat Disease Resistant Germplasm 3.1 Innovation of disease resistance traits in wheat germplasm The innovation of disease resistance traits in wheat germplasm has been significantly advanced through the identification and utilization of resistance genes against major diseases such as stripe rust and powdery mildew. The Indian Wheat Genomics Initiative has highlighted the importance of exploring the genetic diversity available in gene banks to develop stress-resistant cultivars. This initiative has focused on the molecular and phenotypic characterization of conserved genetic resources, which is essential for the improvement of wheat germplasm (Kumar et al., 2022). Additionally, the use of synthetic hexaploids, developed from the hybridization of durum wheat with Aegilops tauschii, has shown promise in enhancing disease resistance traits. These synthetic-derived lines have been evaluated for their agronomic potential, including resistance to biotic stresses, and have demonstrated significant improvements in grain yield and other yield components (Blanco et al., 2001). Moreover, the integration of advanced molecular techniques such as genomic selection (GS) and genome-wide association studies (GWAS) has facilitated the identification of quantitative trait loci (QTLs) associated with disease resistance. These techniques allow for the precise selection of resistant genotypes, thereby accelerating the
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