Molecular Pathogens, 2025, Vol.16, No.2, 69-76 http://microbescipublisher.com/index.php/mp 71 Figure 1ZmWAK-RLK1reduces fungal penetration rates in leaves of maize seedlings (Adopted from Yang et al., 2018) Image caption: (a) Hyphae detected inside of host tissues at 1 d post inoculation (dpi). In the left and right panels the focus is on the epidermis and hyphae, respectively. Red arrows indicate hyphae inside the host tissue. Bars, 100 μm. (b) Rate of successful penetration events at 1 dpi. The genotypes RLK1b, RLK1d and RLK1f are ZmWAK-RLK1 mutants with compromised northern corn leaf blight (NCLB) resistance that were produced in RP3Htn1 (Hurni et al., 2015), whereas genotypes RLK1b-wt, RLK1d-wt and RLK1f-wt are the corresponding sister lines, respectively. Red bar, Htn1 resistance allele; black bar, susceptible allele. The statistical analysis was conducted using Student's t-test in three independent experiments. The asterisks represent significant differences: **, P < 0.01; *, P < 0.05. (c) Rate of successful penetration events at 3 dpi in B37 and B37Htn1. The statistical analysis was conducted using Tukey's Honest Significant Difference in three biological replicates. Lowercase letters above the bars represent significant differences (P = 0.05). Error bars indicate ± SE. WAK, wall-associated kinase (Adopted from Yang et al., 2018) 3.3.2 Genomic analysis of resistance gene conservation and diversity Scientists have found that some disease-resistant genes (like ZmWAK-RLK1) vary greatly in external structures in different corn varieties. This diversity shows that corn has many ways to fight diseases. This difference is very helpful for plants to resist different mycotic diseases (Hurni et al., 2015). 3.3.3 Evolutionary trajectories and adaptive features of resistance genes in different varieties Corn's disease-resistant genes will gradually evolve with changes in the environment, thereby adapting to different pathogens. Taking ZmWAK-RLK1 as an example, it has a structure called non-RD kinase. This structure often appears in the natural immune receptors of plants, indicating that it is also becoming stronger in evolution. Among different corn varieties, researchers have also seen that these genes are expressed differently. This shows that corn is constantly adjusting its disease resistance to cope with various fungal threats (Schurack et al., 2021). 4 Molecular Mechanisms of Fungal Disease Resistance 4.1 Pathogen recognition and host-pathogen interactions In corn, the first step to start a defense response is to recognize fungal pathogens. This process is usually done through proteins called “pattern recognition receptors” (PRRs), which can recognize the characteristic signals of pathogens. Wall-associated kinases (WAK) like ZmWAK-RLK1 play a big role in identifying bacteria of corn spot disease (e.g., Exserohilum turcicum) (Hurni et al., 2015). Most of these kinases are located on the cell surface and can sense foreign bacterial signals at the first time, thereby triggering the corn's defense system (Zhang et al.,
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