Targeted modulation of the shikimate pathway enhances bacterial wilt resistance through NbMEE32 suppression in tobacco

The shikimate pathway serves as a central metabolic route for the biosynthesis of aromatic amino acids and diverse secondary metabolites involved in plant growth and defense. While its contribution to structural and chemical immunity is well recognized, the roles of individual shikimate pathway enzymes in immune regulation remain poorly understood. Here, we characterize NbMEE32, a 3-dehydroquinate dehydratase/shikimate dehydrogenase (DHD/SDH), as a negative regulator of bacterial wilt resistance in Nicotiana benthamiana . Virus-induced gene silencing (VIGS) of NbMEE32 enhances resistance to Ralstonia solanacearum , accompanied by increased shikimate accumulation and lignin deposition in vascular tissues. Exogenous shikimate treatment partially recapitulates defense responses observed in NbMEE32 -silenced plants. Transcriptome profiling indicates that NbMEE32 silencing is associated with extensive transcriptional reprogramming related to defense responses and shikimate-associated metabolism. Together, these findings reveal a previously unappreciated immune-regulatory role of shikimate pathway enzymes and suggest new strategies for engineering disease resistance through metabolic intervention. • NbMEE32, a non-plastid-associated DHD/SDH, negatively regulates bacterial wilt resistance in tobacco. • Silencing NbMEE32 enhances shikimate accumulation and broad defense-related transcriptional reprogramming. • Exogenous shikimate treatment partially recapitulates NbMEE32 silencing and improves disease resistance. • NbMEE32 suppression promotes lignin deposition associated with vascular defense reinforcement. • Non-plastid-associated shikimate-pathway enzymes may function as metabolic constraints balancing growth and immunity.