Bioscience Methods 2025, Vol.16, No.6, 289-298 http://bioscipublisher.com/index.php/bm 293 5 Resistance-Related Regulatory Networks and Functional Validation 5.1 Role of defense signaling pathways in tea plants In the defense system of tea plants, the three plant hormones SA, JA and ET almost play an unavoidable role. Their task assignments are also different - SA is responsible for dealing with live trophic pathogens, while JA and ET are more suitable for dealing with necrotrophic pathogens and some pests (Mishra et al., 2024; Zhang et al., 2025). However, things are not always clear-cut. There are often mutual checks and balances among the three. For instance, the antagonistic effect between SA and JA/ET sometimes makes the defense response more complicated. In some studies, in scenarios such as fungal infections, transcriptome data indicated that the ethylene signaling pathway was particularly active (Hazra et al., 2023), but this does not imply that other pathways were inactive. In fact, NO (nitric oxide) is also involved, regulating the expression rhythms of SA and JA/ET. The defense mechanism is not a straight line; it is more like a net that adjusts to the environment, with resistance genes and metabolic pathways all working closely and flexibly within it. 5.2 Functional studies of key transcription factors There are also many interesting discoveries in the section of transcription factors. Members of the MYB, NAC, WRKY and JAZ families basically all have some role in the immune response. For instance, the relationship between CsMYB72 and CsPR10-9 is not merely a simple promotion or inhibition. CsMYB72 can suppress the expression of CsPR10-9. After silencing it, not only does the activity of antioxidant enzymes increase, but the content of SA also rises, and the resistance is enhanced accordingly (Tao et al., 2025). On the JAZ family side, CsJAZ11 and CsMYC2.2 can form an interactive combination to jointly promote the expression of CsRPM1 of the NS-LRR class. This regulatory mechanism also has a good effect in combating anthrax (Fan et al., 2025). In addition, there is CsNAC29 in the NAC class, which activates CsAFS2 and promotes the synthesis of volatile substances in tea plants, thereby playing a role in combating gray mold (Xu et al., 2025). These examples show that transcription factors are not only transfer stations for signals but also play a key role in coordinating hormone and gene expression. 5.3 Emerging perspectives on epigenetic regulation of resistance Let's turn to the topic of epigenetic regulation. In the past, people might have paid more attention to genes themselves, but now more and more evidence shows that mechanisms like histone modification also play a considerable role in immune responses. CsPRMT5 in tea plants is a protein arginine methyltransferase that can dimethylate H4R3 under normal conditions, thereby suppressing the expression of some defense genes, such as CsMAPK3. However, once tea plants encounter pathogens, the expression of CsPRMT5 will decline, and the level of H4R3sme2 will decrease accordingly. That "brake" is released, and the defense system activates (Peng et al., 2025). On the other hand, mirnas are also at play. Whether for sooty ash disease or anthracnose, they all exert fine-tuning functions at the post-transcriptional level by regulating defense genes and transcription factors (Jeyaraj et al., 2025; Wang et al., 2025). Ultimately, these regulatory measures provide tea trees with a faster and more flexible response mechanism. There is no need to rewrite genes; it is sufficient to switch the expression mode. 6 Case Studies: Advances in Tea Plant Resistance Research 6.1 Development of molecular markers for tea geometrid (Ectropis obliqua) resistance The tea foot moth (Ectropis obliqua) is often seen in tea gardens. Once an outbreak occurs, both the yield and quality of tea may be affected. To better carry out insect-resistant breeding, some research teams have adopted the enriched motif library technology and developed 11 new microsatellite markers. The polymorphisms of these markers are good. Some loci can detect 2 to 8 alleles, and the heterozygosity is also relatively high. They can be used to construct genetic maps or analyze population structure. Their application value is not only reflected in resistance screening, but also can be used to trace the genetic basis of pest resistance variations. On the other hand, transcriptome studies on the feeding of the armymoth have also revealed many clues - tea plants activate a large number of response genes and mirnas. Factors related to pathways such as jasmonic acid, ethylene signaling, and volatile synthesis have also been mobilized (Gu et al., 2024; Yu et al., 2025). These candidate components may become the breakthrough point for future RNAi prevention and control strategies.
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