Molecular Pathogens, 2025, Vol.16, No.1, 27-35 http://microbescipublisher.com/index.php/mp 30 resistance to fungi such as Fusariumand Ceratocystis. SA can activate defense genes like PR-1 and NPR1, which is important for enhancing immunity (Wang et al., 2020). In addition, studies have found many genes that play a role in defense through transcriptome analysis. These include genes related to the MAPK pathway. This pathway can help plants convey the information of pathogens and make the entire defense system move (Lin et al., 2017). 4.3 Role of cell wall modifications in preventing fungal invasion The cell wall of sweet potato can also help it fight fungal attacks. When sweet potato encounters pathogens, it adjusts and strengthens cell wall structure. For example, it accumulates more lignin and phenolic substances on the cell wall. These substances can thicken the cell walls and make fungi more difficult to invade. In potatoes, when the styrene metabolic pathway is activated, more lignin will be produced, which can help potatoes defend against Fusarium solani (Yu et al., 2016). Sweet potatoes have similar ways. Studies have found that if sweet potatoes have thicker cuticles, denser internal tissues of leaves, and higher hair density, they are less likely to get black rot (Samiyarsih et al., 2018). 5 Environmental and Agronomic Factors Influencing Resistance 5.1 Impact of soil conditions on resistance gene expression The soil condition has a great impact on the disease resistance of sweet potatoes. Research has found that genes and environment interact with each other. Different soil types can make some disease-resistant traits manifest differently, such as resistance to sweet potato virus disease (SPVD) may be affected by soil (Ngailo et al., 2019). Nutrients and pH in the soil can also affect the activity of some specific genes. These genes are related to disease resistance and stress resistance. For example, some are involved in "inositol synthesis", and some can help plants fight against various stresses. These changes will make sweet potatoes more adaptable to poor environments (Zhai et al., 2016). 5.2 Influence of climatic stressors on pathogen resistance Environmental problems such as temperature changes, drought and saline-alkali land will also affect the disease resistance of sweet potatoes. In drought or high salt content, genes like IbMIPS1 are activated, helping sweet potatoes to enhance drought resistance and nematode resistance. There is also a gene called IbBBX24, which enhances resistance to Fusarium wilt by regulating the signaling pathway of jasmonic acid. This pathway is particularly sensitive to the external environment. For example, when climate pressure comes, it may affect its activity, thereby changing the resistance level of sweet potatoes (Zhang et al., 2020). 5.3 Interaction between agronomic practices and disease management In addition to genes and environment, the cultivation method will also affect the disease resistance of sweet potatoes. Some practices, such as crop rotation, improving soil, and using disease-resistant varieties, are very helpful in preventing and treating diseases. If you can choose a variety that resists multiple diseases at the same time (such as viruses, nematodes, etc.), the disease will be easier to control (Milczarek et al., 2017). Now, scientists can also use new technologies, such as molecular markers and genome-wide association analysis (GWAS), to find more resistance genes. With these genes, breeding can be more targeted and more disease-resistant sweet potato varieties can be selected (Okada et al., 2019). If the transplantation method can be combined with these gene research, such as looking at how certain disease-resistant genes are expressed in the early or late stages of the disease, a more reasonable and effective prevention and treatment strategy can be formulated (Li et al., 2023). 6 Applications in Sweet Potato Breeding Programs 6.1 Identification of resistance markers for marker-assisted breeding In sweet potato breeding, it is very important to find “marks” related to disease resistance. These markers are like “signals” that can tell us which plants are resistant to disease. Using transcriptome analysis, scientists can discover key genes that play an important role in the defense of sweet potatoes against pathogens such as Fusarium oxysporum. For example, genes such as CERK(a receptor kinase) and MAPK (kinase pathway), as well as some transcription factors called WRKY and NAC, are all related to anti-disease responses (Lin et al., 2017). Now there
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