(retting and decortication) used to separate thefibres from the core (Shahzad 2012 ;
Lebrun et al. 2013 ; Salentijn et al. 2015 ). The characteristics of plantfibres are
determined by the composition of the cell wall (Ebskamp 2002 ). High throughput
systems such as cDNA microarrays are used to identify genes associated withfibre
quality (van den Broeck et al. 2008 ). Subsequent testing of candidate genes requires
manipulation in plant tissues (Ebskamp 2002 ). Thus, a better understanding of cell
wall biosynthesis and regulation is needed for efforts to reduce the variability infibre
quality and allow hemp to better compete againstfibres derived from synthetic or
other crop sources (van den Broeck et al. 2008 ). Similarly, the study and manipu-
lation of biosynthetic pathways involved in the production of secondary metabolites
are facilitated by biotechnological methods (Oksman-Caldentey and Inze 2004 ).
Indeed, most of the biotechnological advances that have been made with Cannabis
focus on the cannabinoid pathway leading to THC production.
Biotechnological applications toward Cannabis research and product develop-
ment are still in their early stages. The Cannabis genome and transcriptome have
recently been elucidated (van Bakel et al. 2011 ). While genetic transformation of
C. sativahas been demonstrated, a major obstacle is the inability to regenerate
transformed plants in tissue culture. To-date, biotechnological advances involving
the study and metabolic engineering of the cannabinoid biosynthetic pathway occur
in heterologous organisms. This chapter will review several biotechnological
advances that have been made with Cannabis and will highlight the role of gene
transfer technologies to demonstrate how they can be used to gain knowledge about
Cannabis biology and biochemistry and, in the not-so-distant future, to develop
tailored products to meet consumer demands.
16.2 Plant Genetic Transformation Using
AgrobacteriumSpecies
The most commonly used technique to deliver genetic material into plant cells,
includingC. sativa, exploits the capabilities of two closely related plant pathogens.
Agrobacterium tumefaciensandA. rhizogeneseach harbour a large tumor-inducing
(Ti)- or root-inducing (Ri)- plasmid, respectively (Zaenen et al. 1974 ; Moore et al.
1979 ). These soil bacteria use similar mechanisms to infect wounded sites and to
transfer a single-stranded copy of a defined segment of their large plasmid into the
host plant genome using bacterial- and plant-encoded proteins (Chilton et al. 1982 ;
Păcurar et al. 2011 ). The transferred DNA (T-DNA) is contained between specific
left and right border sequences on the Ti- or Ri- plasmids (Gelvin 2003 ). In a
separate region of the plasmid, virulence (vir) genes are clustered together and are
responsible for delivering the T-DNA into the host genome (Gelvin 2012 ). The
T-DNA of eachAgrobacteriumspecies encodes genes that function toward the
development of plant disease (Chilton et al. 1977 ; Escobar and Dandekar 2003 ;
Veena and Taylor 2007 ).
16 The Role ofAgrobacterium-Mediated and Other Gene-Transfer... 345