related jasmonates, are endogenous plant hormones which are involved in the stress
response, and are known as transducers of secondary metabolite productions
(Farmer et al. 2003 ). They constitute an important class of elicitors for many plant
secondary metabolic pathways which are typically manifested by the elicitation of
secondary metabolite biosynthesis when plants face particular environmental
stresses (Pauwels et al. 2009 ). Jasmonic acid has been linked to the production of a
range of secondary metabolites includingflavonoids, terpenoids, and alkaloids.
Salicylic acid, well known for the systemic acquired resistance it induces in the
plant response to many pathogens, can also elicit the production of secondary
metabolites in plants (Hayat et al. 2010 ; Pieterse and van Loon 1999 ; Gorelick et al.
2015 ).
However, similar studies have yet to be performed using cannabis. The closest
work involved cannabis suspension cell culture which were treated with jasmonic
acid, methyl jasmonate, or salicylic acid in an attempt to elicit biosynthesis
(Flores-Sanchez et al. 2009 ; Pec et al. 2010 ). While there was a change in
metabolites identified, with a significant increase in tyrosol, no change in
cannabinoid content was observed. However, this study highlights the difficulties of
tissue culture as a model for the whole plant. While the whole plants produce
significant amounts of cannabinoids, almost all studies using cannabis tissue culture
report trace levels of cannabinoids at best (Flores-Sanchez et al. 2009 ) with only
one exception (Farag et al. 2013 ). This phenomenon may be at least partially
explained by the source of the harvested tissue which was cultured.
Another hormone which has been studied in cannabis plants is abscisic acid
(ABA). ABA plays a central role in plant responses to several stresses (Bari and
Jones 2009 ; Ton et al. 2009 ). It affects the biosynthesis of several osmocompatible
solutes and secondary metabolites, such as anthocyanins in Arabidopsis
(Arabidopsis thaliana) (Loreti et al. 2008 ) and terpenoid indole alkaloids in
Catharanthus roseus(El-Sayed and Verpoorte 2004 ). In these two plants, both
biosynthesis pathways are also controlled by jasmonates. Synergistic as well as
antagonistic interactions can occur between ABA and JA (Lackman et al. 2011 ). In
cannabis, ABA produced conflicting responses. In vegetative plants, ABA
decreased THC and CBD content as well as phytosterol content (Mansouri and
Asrar 2012 ). However, inflowering female plants, ABA increased the THC content
(Mansouri et al. 2009 ). Interestingly, there was a decrease in primary terpenoids
observed, suggesting that ABA treatment may affect the terpenoids biosynthetic
pathways via 1-deoxy-d-xylulose 5-phosphate synthase, favoring the production of
secondary terpenoids. However, more research is needed to better understand the
role of ABA in cannabinoid biosynthesis.
While the evidence is far from conclusive and more extensive studies are needed
to adequately characterize the chemical ecology of cannabinoids in cannabis,
environmental factors can be harnessed to address the previously mentioned issues
for the development of cannabis. Although the exact role of cannabinoids in plants
is not clear, it is quite possible that eliciting the stress response may stimulate the
production of cannabinoids and related compounds.
448 J. Gorelick and N. Bernstein