metabolic engineering of the cannabinoid pathway (Sirikantaramas et al. 2004 ;
Taura et al. 2007 ; Gagne et al. 2012 ; Zirpel et al. 2015 ). Future efforts should focus
on obtaining a detailed understanding of the regulatory mechanisms controlling
cannabinoid biosynthesis (Oksman-Caldentey and Inze 2004 ; van Bakel et al. 2011 ;
Das et al. 2015 ).
Cannabis extracts are believed to treat many illnesses however there have been
very few clinical studies on the efficacy and safety of individual cannabinoids (Hill
et al. 2012 ; Hofmann and Frazier 2013 ; Devinsky et al. 2014 ). The biotechnological
developments with Cannabis reviewed here have created new possibilities for the
study of cannabinoids. In the near future, individual or precise mixtures of unique
cannabinoids will be synthesized in quantity and be made available for research and
clinical studies to evaluate their therapeutic effectiveness for particular medical
conditions (Hill et al. 2012 ;Crew 2015 ). Biotechnology companies such as Librede
Inc. have incorporated these concepts into their business plan to commercialize new
cannabinoid-based therapeutics (http://www.librede.com/products/). Exciting times
lie ahead for Cannabis-based therapies and we should expect to see a growing
number of developments in the foreseeable future.
Despite the advances made in Cannabis research using gene transfer technolo-
gies, the inability to efficiently generate transgenic Cannabis plants creates obstacles
for future work with this plant. Cannabis transformation would be a valuable
research tool for applications such as the study of gene function (Stout et al. 2012 ;
see Sect.16.4.1.2) and protein trafficking (Sirikantaramas et al. 2005 ; see
Sect.16.4.1.1) in the native organism. Cannabis is a multi-use crop so the ability to
transform the plant would be useful toward developing specialized products des-
tined for industrial or agricultural purposes. Hemp seed is becoming a more popular
source of protein and oil for human and animal consumption (Laate 2012 ; Carus
et al. 2013 ). Despite its excellent nutritional qualities (Callaway 2004 ), hemp seed
tends to contain high levels of phytic acid, an organic form of phosphorus present in
plant seeds that cannot be digested efficiently (Galasso et al. 2016 ). Phytic acid
reduces protein digestibility, amino acid availability and can cause mineral defi-
ciencies (Shi et al. 2007 ). Breeding efforts to reduce phytate in crops have resulted
in undesirable agronomic characteristics (Raboy 2007 ). Shi et al. ( 2007 ) identified a
gene encoding an ABC transporter that when down-regulated in transgenic maize
and soybean seeds, resulted in reduced levels of phytic acid without compromising
seed quality. Thus, there is potential to generate low-phytate hemp seed using gene
transfer technologies for improved digestibility.
As mentioned earlier, a challenge to cultivating hemp forfibre or seed are the
regulatory restrictions in place to prevent accidental or intentional cultivation of
drugs (Bifulco and Pisanti 2015 ; Rehm and Fischer 2015 ; Spithoff et al. 2015 ),
which curtails the use of hemp as a thriving crop. Canada and the European Union
only permit cultivation of hemp plants containing less than 0.3% and 0.2% THC
content, respectively (Salentijn et al. 2015 ; Weiblen et al. 2015 ). Increasing
knowledge of the cannabinoid pathway will lead to the generation of transgenic
hemp cultivars with parts or the entire cannabinoid pathway knocked out. With the
advent of genome editing technologies, key genes along the THC biosynthetic
16 The Role ofAgrobacterium-Mediated and Other Gene-Transfer... 357