methicillin resistantStaphylococcus aureus(MRSA), was not strongly linked to the
nature of the prenyl moiety as CBD, CBC, CBG, and THC were all quite active.
Considering the strong evidence supporting the antibacterial activity of
cannabinoids, no work has been done investigating their ecological defensive role
against phytopathogenic bacteria. A number of bacterial pathogens of cannabis
have been characterized including xanthamonas and pseudomonas (Mcpartland
et al. 2000 ). In addition, the cannabis microbiome is beginning to be elucidated
(Winston et al. 2014 ). Endophytic bacteria have even been implicated in playing a
defensive role against bacterial pathogens (Kusari et al. 2015 ), paving the way for
future work in understanding the potential role of cannabinoid biosynthesis in the
cannabis defense response. This research must be performed before bacterial elic-
itors can be suggested.
Cannabis has also been associated with anti-fungal properties. Much of this
activity may be due to a number of volatile terpenoids, known for their anti-fungal
activity (Wanas et al. 2016 ). In addition, isolated cannabinoids, THC and CBD
were shown to inhibitPhomopsis ganjae(McPartland et al. 1984 ). Other minor
cannabinoids were also found to be active against candida (Radwan et al. 2009 ).
There has been some work involving the fungal elicitation of cannabis.
However, to date, these studies have only been performed in cannabis cell sus-
pension studies (Flores-Sanchez et al. 2009 ). Mycelial suspensions from 2 fungal
strains,Pythium aphanidermantumandBotrytis cinerea, known to infect cannabis,
as well as yeast extract, and pectin elicited a change in various metabolites
including an increase in tryptophan, fumarate, aspartate, and glutamine in cannabis
cell cultures. However, similar to other studies which utilized cannabis suspension
cultures, no cannabinoids were detected. Further research using whole plants or at
the very least cultures harvested from appropriate plant organs is needed in order to
better understand the role of fungal elicitors in cannabinoid biosynthesis. Another
important factor which must be considered is the role of endophytes in the elici-
tation response. Like in other plants, a multitude of fungal endophytes have been
identified in cannabis (Kusari et al. 2014 ). A number of identified endophytes
where even shown to antagonize known cannabis pathogens including botrytis and
trichothecium (Kusari et al. 2013 ). It is quite plausible that endophytic fungi may
also modulate cannabinoid biosynthesis in the host plant, in addition to phy-
topathogenic resistance. This phenomenon must be taken into consideration in
future fungal elicitation research.
21.10 Hormones
Various plant hormones have been extensively used in elicitation studies. The most
studied, due to their key roles in the plant defense response, are jasmonic acid
(JA) and its derivatives and salicylic acid (SA) and derivatives. Jasmonic acid and
21 Chemical and Physical Elicitation... 447