The tRNA thiolation-mediated translational control is essential for plant immunity

Plants have evolved sophisticated mechanisms to regulate gene expression to activate immune responses against pathogen infections. However, how the translation system contributes to plant immunity is largely unknown. The evolutionarily conserved thiolation modification of tRNA ensures efficient decoding during translation. Here we show that tRNA thiolation is required for plant immunity inArabidopsis. We identify acgb Arabidopsismutant, which is hyper-susceptible to the pathogenPseudomonas syringae. CGBencodes ROL5, a homolog of yeast NCS6 required for tRNA thiolation. ROL5 physically interacts with CTU2, a homolog of yeast NCS2. Mutations in eitherROL5orCTU2result in loss of tRNA thiolation. Further analyses reveal that both transcriptional reprogramming and translational reprogramming during immune responses are compromised incgb.Notably, the translation of the salicylic acid receptor NPR1 is reduced incgb, resulting in reduced salicylic acid signaling. Our study not only reveals a new regulatory mechanism for plant immunity but also uncovers a new biological function of tRNA thiolation.