Triticeae Genomics and Genetics, 2024, Vol.15, No.5, 277-286 http://cropscipublisher.com/index.php/tgg 279 triticale breeding by reducing the environmental variability that typically affects phenotypic selection (Figure 1) (Wani et al., 2018). Figure 1 Various types of abiotic stresses affecting plant growth and the complex mechanisms involved leading to plant senescence (Adopted from Wani et al., 2018) 3.2 Use of genome-wide association studies (GWAS) to identify stress-tolerance loci Genome-wide association studies (GWAS) have become a key approach in identifying loci linked to stress tolerance in crops, including triticale. GWAS scans the genome for associations between genetic markers and phenotypic traits, allowing breeders to pinpoint quantitative trait loci (QTLs) linked to important stress tolerance mechanisms. Recent studies in triticale and related crops have used GWAS to identify significant QTLs for drought, salinity, and disease resistance, enabling the development of more resilient cultivars. For example, GWAS in wheat and triticale has identified multiple QTLs related to leaf rust, yellow rust, and powdery mildew resistance, facilitating marker-assisted breeding for these traits (Pang et al., 2021). The combination of GWAS with genomic prediction models has been shown to enhance the efficiency of breeding programs by providing more accurate predictions of stress tolerance traits across different environments (Mathew et al., 2019). 3.3 Role of genomic selection (GS) in accelerating breeding for complex traits Genomic selection (GS) represents a significant advancement in plant breeding, particularly for complex traits like stress resistance, which are often controlled by multiple genes. GS uses genome-wide markers to estimate the breeding values of individuals, allowing for more accurate selection of desirable traits across generations. In triticale, GS has been employed to improve traits such as drought and heat tolerance by enabling breeders to select for multiple small-effect genes that contribute to overall stress resilience (Jim, 2024). Studies in crops such as alfalfa and wheat have demonstrated that GS outperforms traditional MAS, particularly for complex traits like biomass yield under stress conditions (Figure 2) (Medina et al., 2021). GS is particularly effective when combined with high-throughput phenotyping and multi-environment trials, which allow breeders to predict how new cultivars will perform under varying environmental conditions, thus accelerating the breeding cycle and improving genetic gains (Bhandari et al., 2018). 4 Integrating Multi-Omics Approaches to Enhance Stress Tolerance in Triticale 4.1 Transcriptomic studies identifying stress-responsive genes in triticale Transcriptomics has become an essential tool in identifying stress-responsive genes in triticale, allowing for a deeper understanding of the molecular mechanisms underpinning stress tolerance. Transcriptomic analyses provide insights into gene expression profiles under various stress conditions, such as drought, salinity, and heat stress. These studies have revealed that key genes involved in stress responses, including those regulating osmotic adjustment, antioxidant defense, and hormonal signaling, are upregulated under stress conditions. By identifying specific stress-responsive transcripts, breeders can focus on incorporating these genes into elite triticale lines through advanced breeding techniques like marker-assisted selection (MAS) (Bjornson et al., 2017). Furthermore, the integration of transcriptomic data with other omics platforms, such as proteomics and metabolomics, enhances the accuracy of identifying critical genes involved in stress adaptation.
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