Proposed model for the role of LecRK1 in the N. attenuata defense response against M. sexta. During herbivory by M. sexta larvae, the larval OS induce the expression of the LecRK1 gene, however, LecRK1 is also constitutively expressed. The induction of LecRK1 depends on the activity of SIPK and WIPK, which in parallel activate the biosynthesis of JA.16 JA is conjugated to Ile to form JA-Ile, and TD supplies Ile for this biosynthetic process.28 JA-Ile induces the accumulation of defense metabolites or proteins (including nicotine, TPIs, HGL-DTGs and TD) via COI1-dependent mechanisms29,30 and inhibits the expression of LecRK1. LecRK1 suppresses the accumulation of SA induced by M. sexta herbivory which in turn allows for an unfettered induction of the defense metabolites nicotine, TPIs, HGL-DTGs and TD. LOX3: lipoxygenase 3; 13-HPOT: 13S-hydroperoxy-octadecatrienoic acid; SIPK, SA-induced protein kinase; WIPK, Wound-induced protein kinase; TD, threonine deaminase.