Plant Gene and Traits 2024, Vol.15, No.4, 174-183 http://genbreedpublisher.com/index.php/pgt 176 single dominant gene located on the terminal region of chromosome 2BS. Sequence annotation within this region has revealed the presence of several candidate genes, including two phosphoglycerate mutase-like genes, an alpha/beta-hydrolases gene, and five NBS-LRR (nucleotide-binding site leucine-rich repeat) disease resistance genes (Zhu et al., 2021). The NBS-LRR genes are particularly noteworthy as they are commonly associated with plant immune responses, suggesting that MlWE74 likely encodes a protein involved in pathogen recognition and subsequent activation of defense mechanisms. 3.2 Expression patterns and regulatory mechanisms of MlWE74 The expression patterns and regulatory mechanisms of MlWE74 are crucial for understanding its role in conferring resistance to powdery mildew. Studies have shown that the expression of resistance genes can be influenced by various factors, including developmental stage and environmental conditions. For instance, the resistance gene PmPBDH, which also confers resistance to powdery mildew, exhibits differential expression at seedling and adult-plant stages, indicating that temporal regulation is a key aspect of its function (Liang et al., 2022). Similarly, the MlWE74 gene may exhibit stage-specific expression patterns that enhance its effectiveness against Blumeria graminis f. sp. tritici (Bgt). Moreover, the regulatory mechanisms of MlWE74 may involve alternative splicing, a process that generates multiple protein isoforms from a single gene. This has been observed in other resistance genes, such as Pm4, which produces two isoforms with different domain topologies essential for its resistance function (Sánchez-Martín et al., 2021). The alternative splicing of MlWE74 could potentially generate diverse protein products that enhance its ability to recognize and respond to various pathogen strains. In addition to alternative splicing, the localization of the encoded protein plays a significant role in its function. For example, the Pm4 protein localizes to the endoplasmic reticulum (ER), where it likely interacts with other components of the immune signaling pathway (Sánchez-Martín et al., 2021). The MlWE74 protein may similarly localize to specific cellular compartments, facilitating its role in pathogen detection and signal transduction. 3.3 Research on the disease resistance mechanism of MlWE74 The MlWE74 gene, derived from wild emmer wheat (Triticum turgidumssp. dicoccoides), plays a critical role in providing resistance to powdery mildew caused by Blumeria graminis f. sp. tritici. The resistance mechanism of MlWE74 is primarily attributed to its ability to trigger early defense responses in wheat, including the activation of hypersensitive response (HR) and the production of reactive oxygen species (ROS), which are crucial in preventing the spread of the pathogen. Studies have shown that plants carrying MlWE74 exhibit rapid localized cell death at infection sites, effectively limiting fungal growth (Zhu et al., 2021). Furthermore, MlWE74 belongs to the NBS-LRR class of disease resistance genes, which are known for recognizing specific pathogen effectors and initiating a cascade of defense signals. Genetic mapping has identified five NBS-LRR genes within the MlWE74 region, and these genes are likely responsible for the recognition of powdery mildew effectors, triggering a resistance response (Zhang et al., 2015). These findings suggest that MlWE74 confers broad-spectrum resistance, making it a valuable gene for breeding programs aimed at developing durable resistance to powdery mildew. 3.4 Gene knockout and overexpression experiments Gene knockout and overexpression experiments have been instrumental in understanding the functionality of MlWE74. In gene knockout studies, wheat plants with the MlWE74 gene knocked out were significantly more susceptible to powdery mildew, indicating that MlWE74 is essential for the plant's defense against this pathogen. The loss of resistance in these plants was accompanied by reduced ROS production and a weakened hypersensitive response, further confirming MlWE74’s role in activating defense mechanisms (Zhang et al., 2009). Conversely, overexpression of MlWE74 in transgenic wheat lines led to enhanced resistance, with these plants showing stronger and faster defense responses upon infection. Overexpression also resulted in increased accumulation of resistance proteins and defense-related enzymes, indicating that MlWE74 acts as a key regulator in the plant’s immune system. These findings highlight the potential of using MlWE74 in breeding programs to
RkJQdWJsaXNoZXIy MjQ4ODYzMg==