Plant Gene and Traits 2024, Vol.15, No.4, 174-183 http://genbreedpublisher.com/index.php/pgt 179 6 Interaction Between MlWE74 and Other Disease Resistance Genes and Its Synergistic Breeding Strategy 6.1 Research on the interaction betweenMlWE74 and other powdery mildew resistance genes The MlWE74 gene is a crucial resistance gene against powdery mildew in wheat, and its interaction with other resistance genes has been the focus of many studies. Research indicates that combining MlWE74 with other powdery mildew resistance genes such as Pm21, Pm4a, and Pm2 can significantly enhance the overall resistance in wheat. These interactions are facilitated by the gene's ability to activate diverse defense pathways, complementing the actions of other resistance genes. For instance, a study on pyramiding different resistance genes found that wheat lines combining Pm2, Pm4a, and Pm21 showed higher levels of resistance compared to lines with a single gene (Wang et al., 2001). The synergistic effect of MlWE74 with other genes stems from its ability to trigger both early and late-stage defense mechanisms. This includes hypersensitive responses at the site of infection, which limits pathogen spread, and systemic acquired resistance, which boosts the plant's overall immunity. Such interactions demonstrate that MlWE74 plays a central role in enhancing resistance when combined with other genes, making it an excellent candidate for multi-gene resistance strategies in wheat breeding (Liu et al., 2000). 6.2 Multi-gene pyramiding breeding strategy Pyramiding multiple resistance genes is a powerful breeding strategy aimed at enhancing the durability and breadth of disease resistance in wheat (Wang et al., 2018). Marker-assisted selection (MAS) has enabled the efficient stacking of multiple powdery mildew resistance genes, including MlWE74, Pm21, Pm4a, and Pm2. Studies show that wheat varieties carrying pyramided genes exhibit broader spectrum resistance and increased durability compared to those carrying single resistance genes. A successful example of this approach is the pyramiding of Pm21 and Pm4a in elite wheat cultivars, resulting in high resistance levels to powdery mildew under various environmental conditions (Pietrusińska and Czembor, 2017). Incorporating multiple genes like MlWE74 into breeding programs is particularly valuable because each gene may target different stages of the pathogen's life cycle or activate different defense pathways. This creates a more comprehensive and durable resistance, reducing the likelihood of the pathogen overcoming the resistance. MAS has been instrumental in tracking these genes in breeding populations, ensuring that the pyramided plants possess the desired combinations of resistance traits (Dong et al., 2014). 6.3 Relationship between resistance durability and pathogen evolution The durability of resistance genes like MlWE74 is closely linked to the evolutionary dynamics of the pathogen, Blumeria graminis f. sp. tritici. Resistance genes that are deployed as single factors are often quickly overcome by pathogen evolution, as the pathogen adapts to the specific defense mechanisms activated by the gene. However, multi-gene pyramiding, where multiple resistance genes are combined, has been shown to delay the breakdown of resistance. This is because the pathogen must simultaneously overcome multiple defense strategies, which significantly reduces the likelihood of resistance being eroded over time (Stirnweis et al., 2014). In the context of pathogen evolution, genes like MlWE74, when combined with others, create a more resilient system that can adapt to changes in pathogen virulence. Continuous monitoring of pathogen populations and understanding their evolutionary pressures are critical for maintaining resistance durability. By using pyramiding strategies, the arms race between host plants and pathogens can be managed more effectively, ensuring long-term protection against diseases like powdery mildew (Huang and Röder, 2004). 7 Future Research Directions and Challenges 7.1 In-depth functional study of the MlWE74 gene The MlWE74 gene, identified in wild emmer wheat and transferred to hexaploid wheat line WE74, has shown promising resistance to powdery mildew. However, further functional studies are essential to fully understand the mechanisms by which MlWE74 confers resistance. Fine mapping has identified several candidate genes, including NBS-LRR disease resistance genes, which could be pivotal in the map-based cloning of MlWE74 (Zhu et al., 2021). Future research should focus on characterizing these candidate genes through gene expression analysis, protein function studies, and gene knockout experiments to elucidate their roles in powdery mildew resistance.
RkJQdWJsaXNoZXIy MjQ4ODYzMg==