Molecular Pathogens, 2025, Vol.16, No.2, 53-60 http://microbescipublisher.com/index.php/mp 54 2.2 Mechanisms of pathogen infection Pathogens like Phytophthora infestans have a set of “routines” to deal with potatoes. It interferes with the potato's own immune system, especially defense-related signaling pathways, such as salicylic acid (SA) and jasmonic acid (JA)-related pathways (Saubeau et al., 2016). It can make these pathways “fail”, which makes it more susceptible to infection. The study found that a transcription factor called StbZIP61 can regulate the synthesis of SA, which is important for resistance to P. infestans. In addition, StMKK5-StSIPK module can activate SA and ethylene signaling pathways, thereby improving the disease resistance of plants (Yang et al., 2023). 2.3 Effects of pathogens on potato growth and yield Pathogens like Phytophthora infestans have a very big impact on potatoes. Infected plants usually don’t grow well and photosynthesis can also be affected. Leaves and tubers are often destroyed, which eventually leads to a significant decline in yield (Zheng et al., 2020). Worse, these pathogens are highly adaptable and spread quickly, making them difficult to control (Zhang et al., 2020). Multiple defense signaling pathways in plants, such as SA, JA and ethylene-related pathways, will participate in the defense response together. But these pathogens can also find ways to bypass these defenses, so it is challenging to prevent and treat (Zhou et al., 2018). 3 Overview of Potato Signaling Pathways 3.1 Classification of signaling pathways: hormonal signals, defense signals, and systemic acquired resistance (SAR) In order to deal with bacteria, potatoes will initiate many signaling pathways. It can be roughly divided into three categories: hormone signals, defense signals, and system acquisition resistance, also called SAR. Hormone signals are mainly three plant hormones: salicylic acid (SA), jasmonic acid (JA) and ethylene (ET), each of which has different functions. Salicylic acid is mainly used to deal with trophic pathogens and is a key ingredient in establishing SAR. SAR is a long-term defense method that can work against a variety of bacteria (Shine et al., 2019; Zeier, 2021). Jasmonic acid and ethylene are more commonly used to defend against saprophytic bacteria and plant-eating insects. These two hormones often work together and can enhance the plant’s defense response (Yang et al., 2020; Yan et al., 2022). 3.2 Key signaling molecules: salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) These three hormones-SA, JA, and ET-are the “commanders” of the entire defense pathway. Studies have found that when plants are attacked by pathogens, SA increases rapidly, and then activates some disease-resistant genes (called PR genes) to increase resistance (Saubeau et al., 2016). JA is responsible for regulating a portion of the genes related to defense. ET mainly helps fight disease by regulating various defense enzymes and transcription factors. These three hormones are not each doing their own, but are connected to each other. Sometimes, JA and ET inhibit the signaling effect of SA, allowing plants to choose different coping methods based on different bacteria (Wang, 2024). 3.3 Cross-regulation among signaling pathways The “match” between these signaling pathways is an important part of plant defense. SA, JA, and ET not only work alone, they also influence each other. For example, sometimes SA and JA/ET “dry” against each other, but in some cases they will also cooperate to activate certain defense proteins, such as calmodulin kinase (CDPK) and RPM1-interacting protein 4 (Yang et al., 2023). This mutual cooperation can help plants find a balance between “growth” and “disease prevention”. In general, these signaling pathways in potatoes form a very flexible system that can adjust the response according to different situations, thereby more effectively fighting various bacteria. 4 Potato Signaling Pathways in Response to Phytopathogens 4.1 The salicylic acid pathway and its role in defense The salicylic acid pathway is an important method used by potatoes to deal with bacteria. It can initiate many defense reactions, such as expressing pathologically related proteins (PR proteins) and enhancing plant systemic gain resistance (SAR). After potatoes are infected with Phytophthora infestans, expression of SA-related genes such as EDS1, WRKY1, PR-1 and PR-2 is significantly increased (Saubeau et al., 2016). Studies have found that
RkJQdWJsaXNoZXIy MjQ4ODYzNA==