16.1 Introduction
Cultivated forms ofCannabis sativa, which include marijuana and hemp, represent
multi-purpose crops that are valued for their pharmacological properties and for
fibre, seed and oil. Marijuana cultivars are bred for a high content ofD^9 -tetra-
hydrocannabinol (THC), the principal cannabinoid responsible for the plant’s
psychoactive effects (Baker et al. 2003 ; Weiblen et al. 2015 ). Medicines containing
THC are sold for the treatment of nausea, vomiting and loss of appetite caused by
HIV/AIDS and cancer chemotherapy and for pain management and spasticity in
multiple sclerosis patients (Stott and Guy 2004 ; Hill et al. 2012 ; Velasco et al.
2012 ). Hemp cultivars are bred forfibre, seed and oil and have a low THC content
(Carus et al. 2013 ; Weiblen et al. 2015 ). Hemp seed and oil are popular as a healthy
food. The seeds are high in essential and polyunsaturated fatty acids, they provide a
rich source of amino acids in an easily digested protein and contain considerable
amounts of vitamins and minerals (Callaway 2004 ; Galasso et al. 2016 ). Hempfibre
cultivars supply both cellulosic and woodyfibres for several industries such as
specialty pulp and paper (González-García et al. 2010 ; Carus et al. 2013 ), textiles
(Ebskamp 2002 ) and green biocomposites (Kim and Netravali 2011 ; Lebrun et al.
2013 ; Baghaei et al. 2014 ).
Gene transfer technologies represent a notable feature of biotechnology that are
used to introduce genetic material into cells and to facilitate its integration into the
genome of host organisms. Scientists have harnessed the capability to genetically
engineer organisms and there now exists several routine laboratory techniques used
to clone a gene of interest into a vector and to deliver the recombinant DNA into
cells of many different organisms (Chilton 2001 ). Genetic modification is a wide-
spread occurrence in the natural environment. Horizontal gene transfer is especially
recognized for its role in the increase of multidrug-resistant bacteria (Bock 2010 ;
Blair et al. 2015 ). There are also a growing number of examples of horizontal gene
transfer to eukaryotes (Matveeva and Lutova 2014 ). Recently, wildAgrobacterium
tumefaciensT-DNA sequences have been detected in the genome of cultivated
sweet potato (Kyndt et al. 2015 ).
Gene transfer technologies can be applied towards research and the development
of Cannabis products. The conventional breeding of Cannabis could be assisted by
biotechnology strategies. For example, hemp is a promising candidate for phytore-
mediation of contaminated soils (Campbell et al. 2002 ) owing to its fast growth habit,
high biomass, long tap root and metal tolerance (Ranalli and Venturi 2004 ; Shi et al.
2012 ; Ahmad et al. 2016 ), coupled with the potential of harvesting other commercial
products from the contaminant-accumulating plants (Linger et al. 2002 ; Shi et al.
2012 ). However, hemp could benefit from the development of transgenic cultivars
that are better at accumulating toxins (Singh and Jain 2003 ) by genetic manipulation
of endogenous genes (Ahmad et al. 2016 ). Biotechnology can also provide valuable
tools to study and manipulate biosynthetic pathways. Hemp cultivars are capable of
producing excellent qualityfibre; however, they currently deliverfibre of variable
quality due to factors such as genetics, environmental conditions and methods
344 M. Feeney and Z.K. Punja