Effector Triggered Susceptibility and Immunity in Bacterial Diseases of Leaf Blight and Streak in Rice

Rice (Oryza sativa), a staple crop for over half of the global population, is significantly threatened by bacterial blight (BB) and bacterial leaf streak (BLS), caused by Xanthomonas oryzae pv. oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc), respectively. These pathogens deploy type III secretion system (T3SS) effectors, primarily transcription activator-like effectors (TALes) and Xanthomonas outer proteins (Xops), to suppress host immunity and facilitate infection. This review consolidates recent findings regarding the molecular mechanisms underlying effector-triggered susceptibility (ETS) and effector-triggered immunity (ETI) in rice. It details the structural and functional diversity of TALes and Xops, their host targets, and the associated rice susceptibility (S) and resistance (R) genes. Additionally, the review discusses emerging strategies for engineering broad-spectrum and durable resistance by leveraging CRISPR-based genome editing, effector-guided breeding, and synthetic biology approaches. Conclusively, it highlights unresolved questions and outlines future directions for developing sustainable disease management practices against evolving pathogen threats.