Molecular Pathogens, 2025, Vol.16, No.1, 27-35 http://microbescipublisher.com/index.php/mp 28 Although many specific genes for sweet potato virus resistance have not been found yet, we already know that it is very important to understand these disease-resistant genes. Generally speaking, resistance genes (also called R genes) can help plants recognize viruses. When the virus “invades”, these genes make the plants respond to defensively. The proteins they encode can recognize signals from the virus and then initiate an immune response. Although there are not many studies on sweet potato virus resistance, if we can find these key genes, we can breed more antiviral sweet potato varieties in the future. 2.2 Key genes associated with resistance to fungal pathogens Some studies have now discovered genes related to fungal resistance in sweet potatoes. For example, the gene IbBBX24 can regulate the jasmonic acid pathway. This pathway is related to the plant's defense system and can help sweet potatoes better fight wilt (Zhang et al., 2020). There is also a gene called IbINV, which affects sugar metabolism. Changes in sugar will also affect the resistance of sweet potatoes to black rot (Yang et al., 2023). In addition, there are genes like IbF6’H2 and IbCOSY, which allow sweet potatoes to synthesize a natural substance called scopoltin. This substance can inhibit the growth of fungi, especially preventing diseases caused by Fusarium oxysporum(Wang et al., 2024). These examples illustrate a problem: Some specific genes play a critical role in increasing sweet potato’s resistance to fungal diseases. 2.3 Comparative genomic insights into resistance gene evolution Scientists also used comparative genome methods to study how sweet potatoes “evolved” their disease resistance. In the transcriptome analysis, the researchers found some genes with different expression levels (called differentially expressed genes, DEGs), which are related to defense responses. For example, there are chitin-induced receptor kinase (CERK), mitogen-activated protein kinase (MAPK), and transcription factors such as WRKY and NAC. These genes can help plants recognize pathogens and initiate defenses (Lin et al., 2017). In addition, after combining the transcriptome and metabolic groups, it was found that signal molecules such as salicylic acid and jasmonic acid can also enhance the resistance of sweet potatoes to diseases such as stem nematodes (Qiao et al., 2023). These studies show that the resistance gene of sweet potato does not work in isolation, but can better resist pathogen damage through many signals and metabolic processes. 3 Mechanisms of Resistance Against Viral Pathogens 3.1 Role of RNA silencing pathways in viral defense In plants, RNA silencing is an important defense method, and sweet potatoes are no exception. This process can degrade the virus’s RNA, thereby preventing the virus from continuing to replicate and spread. However, some viruses have learned to “fight back” and they have evolved some proteins to block this defense process. For example, Sweet Potato chlorophyll virus (SPCFV) can produce a protein called NaBp, which can inhibit RNA silencing (Deng et al., 2015). Recently, scientists have tried to use CRISPR-Cas13 technology to deal with these viruses. They designed this system to specifically “recognize” the RNA of the virus, such as the RNase3 gene of the SPCSV virus, so that it can effectively prevent the inhibitory effect of the virus and enhance the resistance of sweet potatoes (Yu et al., 2021; Zhang et al., 2024b). 3.2 Structural and functional analysis of viral resistance proteins 3.2.1 Key structural domains of viral resistance proteins and their functions A domain called NLR is common in the resistant protein of sweet potato. This part can bind viral components and initiate a defense reaction. When these proteins recognize the virus, two reactions may be triggered: one is “local cell death”, that is, the active death of cells at the infection site; the other is “extreme resistance”, which directly prevents virus replication and does not have obvious symptoms (Kopp et al., 2015; Ross et al., 2021). 3.2.2 Molecular mechanisms of interaction between resistance proteins and viral factors A domain called NLR is common in the resistant protein of sweet potato. This part can bind viral components and initiate a defense reaction. When these proteins recognize the virus, two reactions may be triggered: one is “local cell death”, that is, the active death of cells at the infection site; the other is “extreme resistance”, which directly prevents virus replication and does not have obvious symptoms (Kopp et al., 2015; Ross et al., 2021).
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