Triticeae Genomics and Genetics, 2025, Vol.16, No.4, 184-194 http://cropscipublisher.com/index.php/tgg 190 7 Challenges and Strategies 7.1 Gene interaction and epistatic effects Putting multiple disease resistance genes together does not necessarily lead to stronger resistance every time. Sometimes, different genes will affect each other, for example, some effects will be superimposed, while others will interfere with each other. This "cooperation" between genes sometimes makes resistance stronger, but it may also weaken it. Not all resistance gene combinations will have an effect, and the specific performance is related to the genetic background of the plant. Some combinations may even bring unexpected results. Therefore, when breeding for resistance, we cannot only look at genes, but also analyze them together with trait performance to find the best combination (Mundt, 2018; Liu et al., 2020). In polyploid wheat, this interaction problem will be more complicated. Because they have many genes, their functions are sometimes repeated, and some genes are linked together, which increases the difficulty of breeding (Luo et al., 2021; Rajput et al., 2022). 7.2 Maintenance of resistance durability Although combining multiple resistance genes is a promising approach, it is uncertain whether this combination will be effective for a long time. Some pathogens may evolve new abilities to overcome these resistances, especially when the same combination is widely used (Luo et al., 2023). Current studies have found that those combinations that can maintain resistance for a long time usually use the main resistance gene and the adult resistance gene together. However, there is not enough research on whether these combinations can be truly durable (Mundt, 2018). To maintain the long-term effectiveness of resistance, it is necessary to continuously monitor the changes in pathogens and continuously discover and introduce new disease resistance resources. 7.3 Integration with sustainable farming systems Combining disease resistance gene aggregation with sustainable agriculture is a key approach to improving wheat health and yield. Current molecular breeding technologies, such as marker-assisted selection and gene editing, can not only reduce the use of pesticides, but also increase yields while protecting the environment (Laroche et al., 2019; Luo et al., 2023). However, there are still many challenges to adapt these disease-resistant wheats to various agricultural systems. We need to ensure that these varieties are not only disease-resistant, but also high-yielding and suitable for farmers to grow, and also retain other important traits (Luo et al., 2021). One future direction is to use more advanced genomic technologies to introduce new genes from wild wheat or closely related varieties, which can increase genetic diversity. At the same time, it is also necessary to develop breeding strategies that are more in line with sustainable development goals (Ceoloni et al., 2017; Dormatey et al., 2020; Zhang and He, 2024). Although gene aggregation technology has great potential in wheat disease resistance breeding, we also need to solve the problem of gene interactions to make resistance more stable. In this way, we can truly support the development of green agriculture. 8 Concluding Remarks Molecular breeding techniques, such as marker-assisted selection (MAS), QTL mapping, genome-wide association studies (GWAS), and CRISPR/Cas gene editing, have greatly changed the way wheat is bred for disease resistance. These tools can help us find disease resistance genes more accurately and integrate good genes from wild wheat or old local varieties into existing excellent varieties. Breeding has also become faster through high-throughput genotyping and new molecular marker technologies. We can now combine multiple disease resistance genes more efficiently to breed wheat varieties that are resistant to multiple diseases and have longer-lasting resistance. To truly achieve disease resistance and stability, we cannot rely on just one discipline. We need to combine molecular genetics, plant pathology, genomics, bioinformatics, and agronomy. For example, observing the disease in the field, diagnosing the disease with molecular methods, and combining genomic technology, can help us find useful disease resistance genes faster and use them in breeding. Cooperation between breeders, disease researchers, and molecular biologists is also particularly critical. They need to solve many problems together, such as the mutual influence between genes, different performances in different environments, and new challenges brought by the constant changes of pathogens.
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