Field Crop 2025, Vol.8, No.1, 32-40 http://cropscipublisher.com/index.php/fc 35 people are increasingly in need of potato varieties that can withstand adversity and have high yields, not only to have enough food, but also to ensure agricultural income and food security in this region (Slater et al., 2017; Haas et al., 2020). 4.2 Breeding process: grasping the key points of yield with "MAS" To solve the problem, we must start from the source. As a new breeding tool, marker-assisted selection (MAS) has been gradually used in recent years to improve the tuber size and yield of potatoes. Its advantage is that it does not rely entirely on long-term field trials, but uses genetic markers to screen out plants that may perform well in advance. Through QTL analysis, researchers found some key genetic regions related to tuber appearance and specific gravity, which facilitates the focus of subsequent breeding. MAS is also used to locate disease resistance genes, such as resistance genes to late blight, which has played a major role in reducing disease losses (Beketova et al., 2021). However, this technology itself is not omnipotent. It usually has to be combined with traditional methods to truly achieve the goal of high yield and high quality. 4.3 Actual effect: selection and promotion of new varieties In practice, MAS has indeed helped a lot. Researchers have selected a number of stable and high-yield varieties through MAS in multiple breeding projects. Interestingly, one of the cases used the ABF4 gene of Arabidopsis thaliana, and the tuber yield under stress conditions did not decrease but increased, and the storage and processing quality also improved simultaneously (García et al., 2018). From the field point of view, screening depends not only on genes, but also on trait performance (Figure 2). Figure A shows the distribution of fresh weight of tubers in different populations. Such diversity is actually very beneficial for breeding, and the most promising individuals can be selected from them. Part B lists some key steps from field selection to molecular verification, such as environmental multi-point experiments, candidate gene expression analysis, and the assistance of metabolomics data. Figure C uses a Venn diagram to compare the intersection and differences between different screening strategies. The three methods of PPt, MPt and MPs have their own focuses. Combining them can take into account sensitivity and specificity, and it is not easy to miss key genes, and it can also filter out a lot of environmental interference. Figure D further shows the difference in tuber yield under different stress conditions. The results are obvious. The varieties bred by MAS are much better than traditional methods in terms of yield and stability, especially in plots with frequent drought and diseases. Further gene map analysis also helped to identify some genetic markers that may be related to drought tolerance (Haas et al., 2020). In the end, some new varieties with strong adaptability and good yield were promoted and performed well in actual production. They were not only disease-resistant and stress-resistant, but also took into account market demand (Tessema et al., 2022). Figure 2 Selection experiment comparing phenotypic selection and MAS from a potato population segregating for drought tolerance (Adopted from Haas et al., 2020)
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