Molecular Microbiology Research, 2025, Vol.15, No.2, 59-68 http://microbescipublisher.com/index.php/mmr 63 5 Breeding for Stress Resistance 5.1 Types of stress affecting potato crops (drought, salt, heat) During the planting process, potatoes will be subject to a lot of environmental pressure. Among them, drought, high soil salinity and high temperature have the greatest impact. Because the potato has a shallow root system, once the soil is drought, it will be difficult to absorb water from the deep layer, which will seriously affect its growth (Nasir and Tóth, 2022). It is not good to have too high salt in the soil, which will make the potatoes shorter and have fewer stems, and eventually the tuber yield will also decrease (Sanwal et al., 2022). In addition, high temperatures often occur with drought, which further aggravates the adverse effects (Harsselaar et al., 2021). These problems may become increasingly serious as the climate becomes increasingly unstable. Therefore, when breeding, you must consider selecting potato varieties that can resist these adversities. 5.2 Genetic traits conferring stress resistance Some potatoes are naturally more "produced" and have some special genetic characteristics. For example, some varieties can utilize water more effectively and maintain a relatively good photosynthesis rate in arid environments (Gervais et al., 2021). Some salt-resistant varieties have stronger antioxidant enzyme activity in the body, such as superoxide dismutase and catalase, which can reduce oxidative damage caused by stress. There are also studies that varieties with long root systems and deep root systems perform better in drought because they can absorb deeper water (Qin et al., 2022). These characteristics are very helpful for breeding work and are the key direction for improving stress resistance in the future. 5.3 Biotechnological approaches for stress resistance 5.3.1 Use of transgenic techniques Genetically modified technology is to transfer useful genes into potatoes so that it can better cope with adversity. Scientists have added some genes that can synthesize "protective substances", such as genes related to proline and betaine, to potatoes. These ingredients can help plants “tolerate” in arid and high salt environments (Rudack et al., 2017). In addition, some people have added antioxidant enzyme-related genes, such potatoes can more effectively remove harmful substances in the body when facing stress (Sanwal et al., 2022). Through these methods, breeders can develop new varieties that can grow well under harsh conditions. 5.3.2 RNA interference and its applications RNA interference (RNAi) is another genetic technology that mainly silences some "harmful" genes temporarily and weakens their effects. For example, some genes can make potatoes produce too much ethylene under pressure, which can inhibit plant growth. After silencing these genes with RNAi, plants are more drought-tolerant (Spreger et al., 2017). There are also some genes that produce too much reactive oxygen species (ROS) in the plant under pressure, and RNAi can also be used to reduce the production of these substances and enhance antioxidant capacity (Hong and Huang, 2024). These technologies can help us improve potatoes in a targeted manner so that they can grow smoothly in various adverse environments. 6 Role of Molecular Markers in Potato Breeding 6.1 Application of molecular markers in selection processes Molecular marking is a very useful tool in potato breeding. It can help breeders find the traits they want directly at the genetic level. In this way, there is no need to rely entirely on appearance to judge, especially those traits that are invisible or difficult to evaluate, such as disease resistance or stress resistance. Through DNA testing, researchers can find genes related to disease resistance, resilience or metabolic ability, and then select good-performing varieties (Gebhardt, 2013). Nowadays, high-throughput techniques such as transcriptome sequencing can be used to find more useful gene markers, so that breeding efficiency can be greatly improved (Caruana et al., 2019). 6.2 Marker-assisted selection (MAS) case studies The "mark-assisted selection" method has been used in many potato breeding projects. Its advantage is that it can save time and manpower, and can also select good seedlings earlier. For example, Appacale has used this method
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