<scp>TALE</scp> Repertoires in Thai <scp> <i>Xanthomonas oryzae</i> pv. <i>oryzae</i> </scp> Isolates Confer Compatibility With <scp>

Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight (BB) in rice, exhibits substantial genetic diversity and overcomes Xa‐ or xa ‐mediated resistance through the delivery of transcription activator‐like effectors (TALEs). These effectors bind effector‐binding elements (EBEs) in the promoters of susceptibility genes, particularly members of the SWEET gene family. Identifying the molecular compatibility between Xoo strains and resistant rice varieties is crucial for effective BB management. In this study, whole‐genome sequencing and TALE prediction from two Thai Xoo isolates (Xoo16PK001 and Xoo16PK002), identified 17 TALEs. A PthXo1‐like TALE ( TalBX16 ) was only detected in Xoo16PK002 and predicted to target the SWEET11 promoter. In rice variety IRBB13, which carries the promoter‐mutated xa13 allele, the TalBX16‐targeted EBE site was disrupted by a DNA insertion. Upon infection with Xoo16PK002, SWEET11 expression was significantly upregulated in IRBB5 and IRBB21 (carrying Xa13 ) but remained lower in IRBB13. In contrast, Xoo16PK001, which lacks TalBX16 , strongly induced SWEET14 expression in IRBB13, with lower induction in IRBB21 and background expression in IRBB5. Pathogenicity assays revealed that Xoo16PK001 and Xoo16PK002 were compatible with IRBB13 and IRBB5, respectively, while both caused moderate susceptibility in IRBB21. These findings suggest that Xoo16PK001 and Xoo16PK002 employ distinct TALE‐mediated strategies to induce BB by differentially activating SWEET14 or SWEET11 (depending on the rice genetic background). This study highlights the importance of TALE– SWEET interactions in determining Xoo virulence and supports the use of strain‐specific resistance strategies in rice breeding programmes.