Molecular Pathogens 2024, Vol.15, No.3, 106-118 http://microbescipublisher.com/index.php/mp 113 The integration of molecular techniques in wheat breeding programs has revolutionized the development of disease-resistant cultivars. By combining conventional breeding methods with advanced molecular tools, high-throughput phenotyping, and bioinformatics, breeders can more effectively respond to the challenges posed by evolving pathogen populations and changing environmental conditions. This integrated approach holds great promise for ensuring the sustainability and productivity of wheat crops in the face of global food security challenges. 6 Case Studies 6.1 Successful implementation in wheat breeding The integration of molecular breeding techniques has led to significant advancements in developing wheat cultivars with durable resistance to various diseases. One notable success is the deployment of multiple resistance genes through marker-assisted selection (MAS). For instance, the combination of eight resistance genes, including Lr19, Lr34/Yr18/Sr57/Pm38/Ltn1, Sr2/Yr30, Sr26, Sr39, Fhb1, Qfhs.ifa-5A-1, and Qfhs.ifa-5A-2, into a single wheat plant has been achieved, resulting in wheat lines with enhanced resistance to rusts and Fusarium head blight (FHB) (Maré et al., 2020). This approach not only improves disease resistance but also maintains desirable agronomic traits, such as strong dough strength and good bread-making qualities. Another successful implementation is the creation of a wheat resistance gene atlas, which serves as an online directory for identifying and deploying resistance genes. This atlas facilitates the rapid response to evolving pathogen populations by providing breeders with the necessary tools and resources to develop resistant cultivars (Hafeez et al., 2021). The atlas includes information on resistance genes for major wheat pathogens, such as rusts, blotch diseases, powdery mildew, and wheat blast, thereby promoting the development of durable resistance. 6.2 Overcoming specific disease challenges Wheat rusts, caused by Puccinia species, are among the most significant threats to wheat production. The continuous emergence of new rust races with novel virulence necessitates the integration of genomic selection, genome editing, and molecular breeding techniques to develop resistant cultivars (Mapuranga et al., 2022). For example, the positional cloning of partial rust resistance genes, such as Lr34/Yr18 and Yr36, has revealed different protein structures, suggesting that these genes can be functionally heterogeneous. This knowledge allows for a more refined classification and deployment of partial resistance genes, enhancing the durability of resistance (Lowe et al., 2011). Fusarium head blight (FHB) is another major disease challenge in wheat production. The pyramiding of multiple resistance genes, such as Fhb1 and Qfhs.ifa-5A, has been shown to provide effective control against FHB. Marker-assisted selection has been instrumental in combining these genes into elite breeding material, resulting in wheat lines with improved resistance to FHB (Miedaner and Korzun, 2012). Additionally, the use of molecular markers has facilitated the identification and characterization of new resistance alleles, further enriching the genetic basis of resistance in breeding programs (Kaur et al., 2008). 6.3 Lessons learned from field trials Field trials have provided valuable insights into the practical application of molecular breeding techniques for developing disease-resistant wheat cultivars. One key lesson is the importance of combining multiple resistance genes to achieve durable resistance. Single resistance genes are often vulnerable to evolving pathogens, but the pyramiding of multiple genes can provide more robust and long-lasting protection (Liu et al., 2000; Maré et al., 2020). Another lesson is the need for continuous monitoring and evaluation of resistance genes in the field. The dynamic nature of pathogen populations requires breeders to regularly assess the effectiveness of deployed resistance genes and make necessary adjustments. The creation of a wheat resistance gene atlas has proven to be a valuable tool in this regard, enabling breeders to quickly identify and deploy new resistance genes as needed (Hafeez et al., 2021).
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