Molecular Microbiology Research, 2025, Vol.15, No.1, 28-36 http://microbescipublisher.com/index.php/mmr 33 7 Case Studies 7.1 Breeding of sweet potato varieties resistant to viral complex infection (SPVD) To develop a variety that can resist sweet potato virus disease (SPVD), you must first figure out how sweet potatoes deal with viral infection. The study found that the salicylic acid (SA) pathway is activated when sweet potatoes are infected with SPCSV (yellowing dwarf virus) and SPFMV (plumed mottled virus). This pathway is particularly important in defense against viruses (Bednarek et al., 2021). Therefore, during the breeding process, if varieties or genes that can activate the SA pathway can be found, it is possible to breed sweet potatoes that are more SPVD-resistant. 7.2 Selection and promotion of bacterial wilt-resistant varieties Bacterial blight is a big problem in sweet potato cultivation, and it is caused by Ralstonia solanacearum. This disease will cause the whole plant of sweet potato to die, affecting the yield. We can learn from the research experience of potatoes. The study found that the StMBF1c gene in potatoes can enhance resistance through the salicylic acid signaling pathway (Yu et al., 2021). This shows that if genes with similar effects can be found in sweet potatoes, they can be used as targets for breeding and help select more disease-resistant varieties. 7.3 Development of disease-resistant sweet potato using rna interference (RNAi) technology RNA interference (RNAi) is a technique that “shuts” a specific gene. It can block the expression of a certain gene and thus control the occurrence of diseases. This technology has great potential in sweet potato disease-resistant breeding. Some studies have conducted experiments on several sweet potato varieties, and their performance is different after infection with Fusarium oxysporus. Among them, OE-16 (overexpressed strain) grew the best and had healthier roots; while WT (wild type) and Ri-3 (RNAi inhibitor strain) performed worse than OE-16. This shows that increasing gene expression levels like IbBBX24 can help enhance the disease resistance of sweet potatoes. IbBBX24 can regulate jasmonic acid (JA) signaling pathways, which is a hormone that is important for plants to respond to pathogens (Figure 2) (Zhang et al., 2020). The experiment also found that the JA content of OE-16 increased significantly after pathogen infection, while the Ri-3 content was relatively low. This further illustrates the critical role of IbBBX24 in the JA pathway. The increase in JA content can activate more defense-related genes, thereby increasing the plant's resistance to bacteria. The advantage of RNAi technology is that it can specifically "focus" on key genes, such as IbBBX24, for precise regulation. This will improve the disease resistance of sweet potato without affecting its normal growth or yield. In the future, RNAi methods can be used together with traditional breeding methods to make the breeding of disease-resistant sweet potatoes faster and more stable, and will also be very helpful to the sustainable development of the sweet potato industry. 7.4 Field trials: performance and economic evaluation of disease-resistant sweet potato varieties Field trials are crucial to assess the performance and economic feasibility of disease-resistant sweet potato varieties. Using the endophytic bacteria Bacillus amyloliquefaciens YTB1407, it has been shown to enhance resistance to fungal pathogens such as Fusarium solani that causes root rot and Ceratocystis fimbriata that causes black rot (Wang et al., 2020). These trials not only evaluate the effectiveness of the resistance mechanism, but also consider the economic benefits of reducing disease incidence and increasing yield. 8 Challenges and Future Directions in Sweet Potato Disease Resistance Research 8.1 Pathogen variation and resistance breakdown One of the biggest challenges of sweet potatoes to fight disease is that pathogens will change. Many bacteria have strong mutation capabilities, and they adapt to the environment very quickly. This makes the originally effective resistance useless. For example, there are many different variants of Fusarium oxysporum f. sp. batatas (sweet potato specialization type) that causes sweet potato wilt. We must monitor these changes regularly in order to adjust the disease resistance strategy in a timely manner to prevent resistance failure. In addition to changing climates, new strains may also appear, which can make disease-resistant management more complicated (Dahal et al., 2019).
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