Nepeta cataria L. (catnip) can serve as a chassis for the engineering of secondary metabolic pathways.

ObjectiveEvaluation of Nepeta cataria as a host with specific endogenous metabolite background for transient expression and metabolic engineering of secondary biosynthetic sequences. ResultsThe reporter gene GFP::licBM3 as well as three biosynthetic genes leading to the formation of the cannabinoid precursor olivetolic acid were adopted to the modular cloning standard GoldenBraid, transiently expressed in two chemotypes of N. cataria and compared to Nicotiana benthamiana. To estimate the expression efficiency in both hosts, quantification of the reporter activity was carried out with a sensitive and specific lichenase assay. While N. benthamiana exhibited lichenase activity of 676 {+/-} 94 mol g-1 s-1 (Gerasimenko et al. 2019), N. cataria cultivar 1000, and the cultivar Citriodora showed an activity of 37 {+/-} 8 mol g-1 s-1 and 18 {+/-} 4 mol g-1 s-1, respectively. Further, combinatorial expression of genes involved in cannabinoid biosynthetic pathway acylactivating enzyme 1 (aae1), olivetol synthase (ols) and olivetolic acid cyclase (oac) in N. cataria cv. resulted presumably in the in vivo production of olivetolic acid glycosides. ConclusionNepeta cataria is amenable to Agrobacterium-mediated transient expression and could serve as a novel chassis for the engineering of secondary metabolic pathways and transient evaluation of heterologous genes.