Résumé
Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of bacterial leaf blight (BLB) disease in rice, exerting a detrimental impact on the yield of various rice cultivars in Vietnam, notably the Bacthom 7 (BT7) variety. Xoo possesses transcription activator-like effectors (TALEs) which modulate the expression of host genes by specifically binding to the effector-binding element (EBE) sequence in target promoter regions, thereby facilitating bacterial proliferation and pathogenesis on rice plants. Notably, OsSWEET13, a member of the Sugar Will Eventually be Exported Transporter (SWEET) gene family encoding sugar transporter proteins, has been identified as a prominent susceptibility (S) gene for BLB. This investigation focuses on elucidating the role of OsSWEET13 in the susceptibility of BT7 to BLB disease in Vietnam. Vietnamese Xoo (VXO) strains were observed to elicit characteristic BLB symptoms on BT7 and trigger the expression of OsSWEET13 during the course of infection. To further probe this, a clustered regularly interspaced palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) construct targeting the EBE PthXo2A site on the OsSWEET13 promoter was designed and introduced into BT7 rice plants through Agrobacterium tumefaciens, resulting in the creation of rice lines with OsSWEET13 promoter modifications. Upon conducting detailed genotype and phenotype analyses of the gene-edited rice plants, it was ascertained that the mutation exhibited no adverse effects on the principal agronomic traits under scrutiny. Notably, a transgene-free homozygous 3-nucleotide deletion modified rice line displayed diminished OsSWEET13 gene expression and a significant reduction in BLB development upon inoculation with VXO strains. This study unequivocally establishes OsSWEET13 as an S gene for VXO, underscoring its significance in breeding programs aimed at enhancing BLB resistance in the BT7 variety through the utilization of CRISPR/Cas9 technology.