Journal of Tea Science Research, 2024, Vol.14, No.4, 225-237 http://hortherbpublisher.com/index.php/jtsr 230 Figure 2 Plant immune signaling pathways (Adopted from Ngou et al., 2022) Image caption: A, PRR signaling pathway. Ligand perception by PRRs activates multiple kinases, which leads to calcium influx to the cytosol, ROS production, transcriptional reprogramming, and callose deposition. B, Singleton NLR signaling pathway. The ZAR1/RKS1 heterodimer detects the effector AvrAC via association with uridylylated PBL2 by AvrAC. This leads to the activation and oligomerization of ZAR1. The ZAR1 resistosome localizes to the PM and triggers calcium influx, which leads to the HR and cell rupture. C, Helper-NLR-dependent sensor NLR signaling pathway. Recognition of ATR1 by the TNL RPP1 leads to oligomerization and the induced proximity of TIR domains. The TIR domain exhibits NADase activity and produces v-cADPR, which might activate EP-proteins and the helper NLRs (RNLs). Following TNL activation, EP-proteins and RNLs associate with each other and activate downstream immune responses, likely via cation channel activity from the helper NLRs. Timeline on the right indicates the order and duration of each signaling event following ligand/effector perception. Numbers indicate the corresponding signaling events in the figure on the left. Note that the activation of ETI is usually preceded by PTI activation, and the strength and duration of each event vary and are dependent on the PRRs/NLRs that are activated (Adopted from Ngou et al., 2022) 6 Breeding and Biotechnological Applications 6.1 Marker-assisted breeding for disease resistance Marker-assisted selection (MAS) has become a pivotal tool in enhancing tea plant breeding programs, particularly for disease resistance. The identification of molecular markers linked to resistance traits allows for the selection of
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