Cotton Genomics and Genetics 2025, Vol.16, No.3, 137-147 http://cropscipublisher.com/index.php/cgg 139 structures (Zhu et al., 2023). NLR proteins can recognize these effectors and then initiate ETI (effector-triggered immunity). ETI often triggers local cell death, a reaction called hypersensitive response (HR), which can prevent the further spread of pathogens. GRF7 is involved in regulating the expression of NLR genes (such as ADR1 and NRG1), which enhances ETI levels and improves cotton's resistance to Verticillium wilt. In addition, during the ETI process, many immune genes also undergo alternative splicing. In disease-resistant cotton varieties, such splicing events are more common, indicating that they play an important role in defense responses (Li et al., 2024). Figure 1 Chlorosis, necrosis and vascular discoloration of cotton by FOV (Adopted from Bhandari et al., 2020) 3.3 Role of phytohormones (SA, JA, ET) in mediating disease resistance Plant hormones play a central role in the fight against wilt fungi. Salicylic acid (SA) is very important in activating systemic acquired resistance. In disease-resistant cotton varieties, SA content is increased, which can promote the accumulation of ROS and the expression of defense genes (Zhang et al., 2016). Jasmonic acid (JA) is also critical. Genes such as GhOPR9 and GhRFS6 enhance the JA signaling pathway, thereby improving cotton resistance to Verticillium dahliae (Chang et al., 2023). In addition, ethylene (ET) also participates in regulating defense responses together with SA and JA. Together, they form a complex signaling network that regulates the
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