Page 174 - Advances in Textile Biotechnology

Engineering of plants for improved fi bre qualities 155

the identification of large numbers of flax genes, but they are also helping
us to understand the molecular bases underlying the formation of cellulose-

rich bast fibers. For example, the use of flax cDNA microarrays revealed
that the expressions of genes coding for lipid transfer proteins (LTPs) and
arabinogalactan proteins (AGPs) were particularly well correlated with

fibre-elongation and cell-wall thickening, respectively (Roach and Deyho-

los, 2007). Such approaches have also allowed the identification of cell-wall
modifying enzymes such as β-xylosidases and β-galactosidases (Day et al.,
2005b; Roach and Deyholos, 2008).
7.3 Plant engineering methods
Despite public concerns about the safety of engineered plant crops (also
referred to as genetically modifi ed organisms or GMOs), there is no scien-
tific evidence to indicate that such crops are any more dangerous than other

new plant varieties produced through conventional breeding techniques
(Batista and Oliveira, 2009; Twyman et al., 2009). As indicated above, mod-

ifications in fibre structure can be induced by targeting genes associated

with fibre development and/or cell-wall polymer biosynthesis. In both cases,
the objective is to modify the activity (expression) of a given gene (or group
of genes), either by stimulating its activity (up-regulation) or by inhibiting/

reducing its activity (down-regulation). Modifications are achieved by intro-
ducing a small piece of DNA (the ‘transgene’) into the targeted plant and
a number of different mechanisms exist (Kohli et al., 2003).
One of the most commonly used methods of introducing genes into
plants takes advantage of a naturally occurring transformation system
based upon a common soil bacteria (Agrobacterium tumefaciens). This

micro-organism was fi rst identified at the beginning of the 20th century as
being the causative agent responsible for the formation of the crown gall
on plants (Smith and Townsend, 1907). Since then, Agrobacterium has been
widely used as a vector to introduce genes into plant DNA (Batista and
Oliveira, 2009; Gelvin, 2003). In this method, the ‘gene’ to be introduced is

firstly integrated into a loop of circular plasmid DNA (the binary vector)
and then the binary vector is introduced into Agrobacterium for plant
transformation. This method has been used to transform fibre plants such

as fl ax (Mlynarova et al., 1994; Wróbel et al., 2004) and cotton (Zhao et al.,

2006). Despite, the recent banning (2009–10) of Canadian flax imports into
Europe because of concerns about the presence of extremely low quantities

of GM flax in non-GM seed lots, recent studies suggest that engineered fl ax,
as with other engineered plant species, does not represent a danger for the
environment (Batista and Oliveira, 2009; Jhala et al., 2008, 2009). Although
different attempts to engineer hemp have not proved successful (Ebskamp,
2002), the recent development of a transformation and regeneration system

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