Molecular Pathogens, 2025, Vol.16, No.2, 69-76 http://microbescipublisher.com/index.php/mp 70 pustules will appear on the leaves, which will connect together and eventually cause large leaves to necrotize. Once the leaves are broken, the photosynthesis of corn will become worse and the yield may be reduced by 40% (Dey et al., 2015). The prevention and treatment method is generally to combine multiple means, such as a disease-resistant variety, and spray some medicine (bactericides such as Tebuconazole). This method has been shown to significantly reduce the condition and increase yield. In Ethiopia, studies have found that disease-resistant corn and medication can well control this rust (Mohammed et al., 2023). 2.2 Southern leaf blight (Bipolaris maydis) Southern leaf blight is another common corn leaf disease, which is caused by Bipolaris maydis. This disease is particularly prone to break out in humid and warm places. After corn suffers from this disease, bad spots will appear on the leaves, which will dry up and fall over time, affecting photosynthesis, and the yield will naturally drop (Chen et al., 2023). In India, the disease is mainly caused by Bipolaris maydis. However, there are other fungi, such as Curvularia spp. and Alternaria spp., which can also aggravate the condition (Singh et al., 2021). If you want to control this type of disease for a long time, the key is to find the disease-resistant varieties and genes through breeding. Some studies have found susceptibility genes like ChSK1, which are helpful for disease-fighting breeding. 2.3 Fusarium ear rot and stalk rot (Fusariumspp.) These two diseases are caused by Fusarium fungi and are the most serious type of diseases in corn. Corn ears and stems will be infected and rot over time. This may not only lead to lodging, but also contaminate food and bring mycotoxins (Zhang et al., 2021). In China, some studies have pointed out that in some areas, the incidence of stem rot can exceed 25%, and the main pathogen is Fusarium. In terms of prevention and control, it is generally recommended to use disease-resistant varieties and reasonably arrange planting methods. At the same time, we should also pay attention to changes in environmental factors such as weather conditions and field humidity, and monitor them in a timely manner to avoid the spread of diseases (Czarnecka et al., 2022). 3 Identification and Characterization of Resistance Genes 3.1 Quantitative trait loci (QTLs) for fungal disease resistance The study found that some quantitative trait sites (QTLs) are critical to the disease resistance of maize. They can help us understand the genetic mechanisms of corn's resistance to mycotic diseases. For example, some QTLs are related to resistance to Fusarium or Gibberine spike rot, and can also affect yield and cereal quality (Akohoue and Miedaner, 2022). This type of QTL is very useful in breeding, especially when doing genome-assisted breeding. Some people have improved the QTL related to Aspergillus aflatoxin through comprehensive analysis. Doing so will find QTLs with more accurate locations and are more convenient to use in marker-assisted selection (Baisakh et al., 2023; Jiang, 2024). 3.2 Major resistance (R) genes and their functions Some corn disease resistance genes have been clearly studied. For example, ZmWAK-RLK1, which can help corn fight the pathogens that cause northern leaf blight. This gene can alter the infection process of bacteria, making it more difficult for them to enter the plant, thereby reducing disease occurrence (Figure 1) (Hurni et al., 2015; Yang et al., 2018). In addition, there are two important genes called tps21 (Terpene synthase 21) and fomt2 (Flavonoid O-methyltransferase 2). They are often found in disease-resistant corn varieties and are helpful in fighting Fusarium and Gibberella ear rot. 3.3 Comparative genomics of resistance genes across maize varieties 3.3.1 Distribution differences of resistance genes in landraces and commercial varieties The resistance genes of local and commercial varieties are not exactly the same. Some disease-resistant genes, such as Htn1, were initially found in local varieties in Mexico. Now, it has become a common source of resistance in many modern varieties (Yang and Song, 2024). This shows that local varieties are important for preserving disease-resistant genes.
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