face technical constraints and have to compete functionally and economically with
traditional petrochemical production methods (Nielsen 2005; Goldemberg et al.
2008). Consequently, low-cost raw materials, efficient biocatalysis, and product
innovations are all key determinants of success. Accordingly, sugarcane juice is a
readily fermentable low-cost feedstock, and the bagasse, representing outstanding
sources of low-cost green process energy, and fermentable and aromatic compounds (Chandel et al. 2013; Cheng and Zhu 2013; Nielsen 2005). Moreover,
sugarcane has several other traits that give it tremendous potential to become a
critical crop for transition from petrochemical-based to bio-based economies
(Paterson et al. 2013). Then, using sugarcane as a biofactory of novel environmentally friendly products may also offer possible diversification for cane-growers,
as well as reducing the reliance by rural sectors on sugar prices (Nielsen 2005).
Currently, important research groups are involved in this form of biopharming
projects around the world.
Nevertheless, many impasses must be overcome before sugarcane biofactories
can become a commercial fact. To contend with commercial protein production
systems that use well-established molecular protocols in plants such as maize and
tobacco, approaches will need to bring about much higher levels of protein
expression in the transformed sugarcane plants, especially in the stalk. These
challenges will demand the identification, isolation, and amplification of new
promoter regions (both constitutive and inducible), development of novel vectors,
and success with both transcriptional and post-transcriptional gene modification
and silencing. Moreover, the protocols for protein extraction and purification at an
industrial level from vegetative tissues represent a daunting task that has to be
addressed with several innovative strategies. Practical knowledge and skills in this
field are in their infancy, and especially for global industries such as sugarcane
(Paterson et al. 2013).
Constraints related to the long time required for conventional breeding of
sugarcane (i.e., it takes 12–15 years to carry out, test and launch a new variety to
the market) and its highly complex genome (polyploidy and aneuploidy) may be
overcome by using molecular approaches. However, sugarcane exhibits recalcitrance to genetic transformation and several parameters usually need optimization
at the variety level to reach higher transformation efficiencies (Scortecci et al.
2012). Indeed, the first protocol developed for genetic transformation of sugarcane
was particle bombardment (biolistic) of cell suspension, embryogenic callus or
meristem (Bower and Birch 1992; Snyman et al. 2006), but the efficiency of this
method depends on callus formation and plant regeneration, which varies with
genotype and culture conditions (Kaeppler et al. 2000; Scortecci et al. 2012).
Later, Agrobacterium tumefaciens-mediated transformation arose (Arencibia et al.
1998; Brumbley et al. 2008) and was more efficient than biolistics for its higher
stability on transgene expression, which derives from the smaller number of
transgene copies integrated into the genome (Dai et al. 2001; Scortecci et al. 2012).
Nevertheless, Agrobacterium-mediated transformation has shown low efficiency
and is highly genotype- dependent, so that some in vitro culture parameters
140
F. C. Gómez-Merino et al.
traditional petrochemical production methods (Nielsen 2005; Goldemberg et al.
2008). Consequently, low-cost raw materials, efficient biocatalysis, and product
innovations are all key determinants of success. Accordingly, sugarcane juice is a
readily fermentable low-cost feedstock, and the bagasse, representing outstanding
sources of low-cost green process energy, and fermentable and aromatic compounds (Chandel et al. 2013; Cheng and Zhu 2013; Nielsen 2005). Moreover,
sugarcane has several other traits that give it tremendous potential to become a
critical crop for transition from petrochemical-based to bio-based economies
(Paterson et al. 2013). Then, using sugarcane as a biofactory of novel environmentally friendly products may also offer possible diversification for cane-growers,
as well as reducing the reliance by rural sectors on sugar prices (Nielsen 2005).
Currently, important research groups are involved in this form of biopharming
projects around the world.
Nevertheless, many impasses must be overcome before sugarcane biofactories
can become a commercial fact. To contend with commercial protein production
systems that use well-established molecular protocols in plants such as maize and
tobacco, approaches will need to bring about much higher levels of protein
expression in the transformed sugarcane plants, especially in the stalk. These
challenges will demand the identification, isolation, and amplification of new
promoter regions (both constitutive and inducible), development of novel vectors,
and success with both transcriptional and post-transcriptional gene modification
and silencing. Moreover, the protocols for protein extraction and purification at an
industrial level from vegetative tissues represent a daunting task that has to be
addressed with several innovative strategies. Practical knowledge and skills in this
field are in their infancy, and especially for global industries such as sugarcane
(Paterson et al. 2013).
Constraints related to the long time required for conventional breeding of
sugarcane (i.e., it takes 12–15 years to carry out, test and launch a new variety to
the market) and its highly complex genome (polyploidy and aneuploidy) may be
overcome by using molecular approaches. However, sugarcane exhibits recalcitrance to genetic transformation and several parameters usually need optimization
at the variety level to reach higher transformation efficiencies (Scortecci et al.
2012). Indeed, the first protocol developed for genetic transformation of sugarcane
was particle bombardment (biolistic) of cell suspension, embryogenic callus or
meristem (Bower and Birch 1992; Snyman et al. 2006), but the efficiency of this
method depends on callus formation and plant regeneration, which varies with
genotype and culture conditions (Kaeppler et al. 2000; Scortecci et al. 2012).
Later, Agrobacterium tumefaciens-mediated transformation arose (Arencibia et al.
1998; Brumbley et al. 2008) and was more efficient than biolistics for its higher
stability on transgene expression, which derives from the smaller number of
transgene copies integrated into the genome (Dai et al. 2001; Scortecci et al. 2012).
Nevertheless, Agrobacterium-mediated transformation has shown low efficiency
and is highly genotype- dependent, so that some in vitro culture parameters
140
F. C. Gómez-Merino et al.