Molecular Plant Breeding 2025, Vol.16, No.1, 82-92 http://genbreedpublisher.com/index.php/mpb 87 technology is well-recognized in the scientific community. Gene editing can complement traditional breeding and molecular techniques by providing a rapid and precise method to introduce beneficial traits into wheat genomes. The integration of CRISPR/Cas9 with other molecular breeding techniques, such as MAS and GS, holds great promise for developing wheat varieties that can withstand the increasing temperatures associated with climate change. 6 Application of Multi-Omics Integration in Wheat Heat Tolerance Research 6.1 Transcriptomics Transcriptomics has been instrumental in understanding the gene expression changes in wheat under heat stress. Studies have shown that heat stress induces significant alterations in the expression of a wide array of genes, including those encoding heat shock proteins (HSPs), transcription factors, and proteins involved in phytohormone biosynthesis and signaling pathways. For instance, a genome-wide gene expression analysis using the Wheat Genome Array revealed that approximately 10.7% of probe sets displayed more than a two-fold change in expression under heat stress conditions. This includes genes related to primary and secondary metabolism, RNA metabolism, and other stress-related proteins. Additionally, the differential expression of 313 probe sets between heat-tolerant and heat-susceptible genotypes suggests that these genes could be crucial for heat tolerance (Qin et al., 2008). The integration of transcriptomic data with other omics approaches can further elucidate the complex regulatory networks involved in heat stress responses (Chatterjee et al., 2023). 6.2 Metabolomics Metabolomics provides a comprehensive overview of the metabolic changes in wheat under heat stress, identifying key metabolites and metabolic pathways that contribute to heat tolerance. Metabolomic profiling has revealed that heat stress significantly affects amino acid, carbohydrate, and nitrogen metabolism, which are critical for plant stress responses. For example, the accumulation of specific metabolites such as osmoprotectants and antioxidants helps in mitigating the adverse effects of heat stress by stabilizing cellular structures and scavenging reactive oxygen species (Raza, 2020). The integration of metabolomics with transcriptomics has been particularly effective in linking metabolic changes to gene expression, thereby identifying potential biomarkers for heat tolerance (Abdelrahman et al., 2020; Raza, 2020). This approach has facilitated the development of metabolomics-assisted breeding (MAB) strategies, which aim to enhance heat tolerance by selecting for favorable metabolic traits (Raza, 2020). 6.3 Proteomics and epigenetics Proteomics and epigenetics play crucial roles in regulating heat tolerance traits in wheat. Proteomic studies have identified several heat-responsive proteins, including HSPs, which are essential for protein folding and protection under stress conditions (Chatterjee et al., 2023). These proteins help maintain cellular homeostasis and protect against heat-induced damage. Additionally, epigenetic modifications such as DNA methylation and histone modifications have been shown to influence gene expression in response to heat stress. These modifications can lead to the activation or repression of stress-responsive genes, thereby modulating the plant's ability to cope with high temperatures (Ni et al., 2017). The integration of proteomic and epigenetic data with other omics approaches provides a holistic understanding of the molecular mechanisms underlying heat tolerance and can guide the development of heat-tolerant wheat cultivars (Ni et al., 2017; Chatterjee et al., 2023). 7 Success Stories in Wheat Heat Tolerance Breeding 7.1 Wheat varieties with high heat adaptability Several wheat varieties have been developed and promoted for their high heat tolerance, demonstrating significant resistance effects. For instance, the study by Al-ashkar et al. (2023) identified new wheat lines such as DHL25, DHL05, DHL23, and DHL08, along with the cultivar Pavone-76, as promising genetic sources for heat-tolerant breeding programs. These varieties were classified based on agro-physiological indices and multidimensional analyses, showing high heritability and genetic gain under heat stress conditions. Additionally, the research by Khan et al. (2022a) characterized 194 historical wheat cultivars of Pakistan, identifying loci associated with heat tolerance at the seedling stage. The study highlighted the potential of these cultivars to sustain high temperatures,
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