Molecular Pathogens, 2025, Vol.16, No.6, 257-265 http://microbescipublisher.com/index.php/mp 261 to be fair, although markers are useful, they are not omnipotent. Under different genetic backgrounds, some markers may not be so "accurate", so the verification step cannot be skipped. 5.2 Application of gene editing (CRISPR/Cas) in improving virus resistance In recent years, CRISPR/Cas has frequently appeared in research on potato disease resistance. Especially those Cas13 systems that can directly target RNA, such as Cas13a and Cas13d, have been successfully tested in multiple transgenic strains. They can directly cut viral RNA and have good inhibitory effects on PVY, PVX, PVS and even PLRV (Adilbayeva et al., 2025). However, the strength of this resistance is often related to the expression level of CRISPR; the stronger the expression, the more obvious the protection. Some people have also attempted to combine multiple guide Rnas to develop a "multi-pronged" strategy, hoping to combat multiple viruses simultaneously (Zhan et al., 2023). To bypass the regulatory challenges of genetically modified organisms, some people are now exploring ways to directly package Cas proteins and guide Rnas into cells without using DNA. This approach seems more suitable for the development of non-genetically modified products (Taliansky et al., 2021; Tiwari et al., 2022). 5.3 Transgenic and antisense RNA strategies to enhance viral resistance Before CRISPR became popular, traditional transgenic methods had already achieved many results in the prevention and control of potato viruses. For instance, by introducing the virus's capsid protein gene or replication enzyme fragment into potatoes, the plants can "recognize the enemy" in advance and interfere with the virus. RNA interference (RNAi) and antisense RNA techniques have also been used for a long time. By designing constructs that can block the accumulation of viral RNA, the symptoms of the disease have been alleviated significantly (Khoo et al., 2024). Although these methods are not new, when combined with CRISPR technology, they can still produce some synergistic effects, especially in terms of resistance stacking or long-term control, providing a sustainable and less pesticide-dependent solution (Taliansky et al., 2021). 6 Case Studies: Application of Resistance Genes in Potato Virus Management 6.1 Successful application of Ry gene in PVY-resistant breeding Many breeding projects have regarded the Ry gene as the core means to control PVY in practice, especially the types Rysto, Ryadg and Rychc, which have strong resistance to almost all PVY strains (Elison et al., 2020; Paluchowska et al., 2024). Rysto originally originated from Solanum stoloniferum. The TIR-NLR protein encoded by it can stably function at different temperatures. Whether the material is selected through transgenic methods or molecular labeling, it basically shows no symptoms (Torrance et al., 2020). Nowadays, multiplex PCR and molecular markers have made the detection and combination of these genes much simpler. Some new varieties in Europe, Russia and Asia have basically used these methods to select materials resistant to PVY (Figure 2). It is worth mentioning that these Ry genes have also helped farmers reduce their reliance on pesticides, and the yield has become more stable. They are now a "main option" for sustainable control of PVY. 6.2 Functional identification of Rx gene for PVX resistance and its commercialization Although PVX itself is not as harmful as PVY, it has relatively high requirements for the quality of seed potatoes. Therefore, the role of the Rx gene in breeding cannot be ignored. It was first found in the Solanum tuberosum ssp. andigena subspecies of potato. It can effectively prevent the spread of PVX, and the process does not trigger cell death. The Rx1 allele demonstrated the ability to block the transmission of viruses from leaves to tubers in experiments, which is particularly crucial for virus-free seed potatoes. At present, in some countries including China, there are already multiple varieties carrying Rx1 or Rx2. Precise breeding is achieved through molecular marker methods, and these varieties show relatively persistent resistance to PVX (Shaikhaldein et al., 2018; Liu et al., 2021). However, a current issue is that the genetic diversity of such genes in commercial varieties is still insufficient, and in the long term, it may plant the hidden danger of resistance decline. 6.3 Comparative analysis of PLRV resistance gene breeding projects in the Netherlands and China When it comes to resistance breeding of PLRV, although the approaches of the Netherlands and China have their own focuses, the basic paths are quite similar: both first search for genes from wild Solanum plants and then
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