Biotic stress caused by Tetranychus urticae mites elevates the quantity of secondary metabolites, cannabinoids and terpenes, in Cannabis sativa L.

Abstract

Secondary metabolites are known to play a role in the plant's defense system, which can be triggered by biotic or abiotic stress. Cannabis (Cannabis sativa L.) plants and mainly their female flowers, have a variety of bioactive metabolites, predominantly cannabinoids and terpenes, which are synthesized and secreted by the trichomes. Many studies have examined their chemistry and bioactive effects; however, there is insufficient information on the effect of biotic stress on the presence of secondary metabolites in cannabis. The present study examined the effect of a well-known cannabis pest, Tetranychus urticae, on the occurrence and concentration of cannabinoids and terpenes in cannabis leaves and flowers. Six cannabis plants were infested with T. urticae mites (treatment group), and six plants were used as the control group. Cannabinoids and terpenes were analyzed and quantified by liquid chromatograph mass spectrometer and gas chromatograph mass spectrometer, respectively. The contents of several cannabinoids and terpenes increased significantly in the leaves of the treatment group of plants in their late vegetative phase as the mite population increased, compared with the control group. Significantly increased content of almost all terpenes, and the cannabinoids; Δ9-tetrahydrocannabinol, cannabichromene, and cannabigerol, was also seen in mature flowers of the treatment group plants, compared with the control group. Thus, cannabis plant infestation has an impact on its secondary metabolites, cannabinoids and terpenes, reflected by an overall increase in these compounds.