length polymorphisms (AFLPs), and simple sequence repeats (SSRs) and sequence
data (reviewed by D’Hont et al. 2008). As a result of these analyses, it has been
assumed that the genus Saccharum is a well-defined lineage that has diverged over
a long period of evolution from the lineages leading to the Erianthus and
Miscanthus genera (Grivet et al. 2006; D’Hont et al. 2008) and that cultivated
sugarcanes probably emerged from wild Saccharum species, while secondary
introgressions with other genera are not likely pathways (D’Hont et al. 2008).
The Saccharum species are not only polyploid, but also autopolyploid (hosting
more than two sets of homologous chromosomes derived from a single species)
and allopolyploid (possessing two or more unlike sets of chromosomes from
different species) (Sreenivasan et al. 1987; Besse et al. 1997), which represent a
tremendous challenge for breeders that normally base their statistical genetic
approaches on models developed for diploid organisms.
A summary of the genetic characteristics of the Saccharum species and the
‘‘Saccharum complex’’ is shown in Table 5.1.
As a relatively recently domesticated species, sugarcane exhibits little of the
available genetic diversity having been incorporated or actively analyzed for
introgression into domesticated varieties (Dillon et al. 2007; OGTR 2011;
Sreenivasan et al. 1987), and breeding programs in the early 1900s focused on
hybridization of S. officinarum clones, but quickly progressed to interspecific
crosses incorporating S. spontaneum. This resulted in improved agronomic traits,
such as tilling, stand and trashiness abilities, ratooning and disease resistance, but
required a backcrossing program to S. officinarum, called ‘‘nobilization,’’ to elevate the sucrose content (Dillon et al. 2007; Edmé et al. 2005). Since then, the
majority of breeding programs have focused on intercrossing between the hybrids,
though in recent decades the larger increases in genetic gains have been made by
incorporating more diverse germplasm into the cultivated backgrounds (Edmé
et al. 2005; Dillon et al. 2007) not only to increase sucrose production, but also to
diversify into other alternative products to regain profitability.
As a C4 carbohydrate metabolism plant having a perennial life cycle, sugarcane
is one of the most productive cultivated plants. Apart from producing sugar, this
crop has gained increased attention because of its importance as a biofuel source
among other value-added products developed from sugarcane biopharming using
molecular approaches. Nevertheless, sugarcane has one of the most complex
genomes among cultivated plants, which has long hampered the development of
crucial areas such as genetics to support breeding for crop improvement programs.
With the advent of molecular techniques, the sugarcane genome has become less
mysterious, although its complexity has still been confirmed in many aspects
(D’Hont et al. 2008).
In this chapter, we review the current status of sugarcane as a potential
biofactory focusing particularly on the production of pharmaceutical proteins,
biopolymers, and alternative carbohydrates; topics related to the use of sugarcane
for bioenergy generation have been thoroughly addressed elsewhere (Arruda 2012;
de Siqueira et al. 2013; Kuan et al. 2013; Vermerris 2011) and therefore will not be
discussed herein.
5 Sugarcane as a Novel Biofactory: Potentialities and Challenges
131
data (reviewed by D’Hont et al. 2008). As a result of these analyses, it has been
assumed that the genus Saccharum is a well-defined lineage that has diverged over
a long period of evolution from the lineages leading to the Erianthus and
Miscanthus genera (Grivet et al. 2006; D’Hont et al. 2008) and that cultivated
sugarcanes probably emerged from wild Saccharum species, while secondary
introgressions with other genera are not likely pathways (D’Hont et al. 2008).
The Saccharum species are not only polyploid, but also autopolyploid (hosting
more than two sets of homologous chromosomes derived from a single species)
and allopolyploid (possessing two or more unlike sets of chromosomes from
different species) (Sreenivasan et al. 1987; Besse et al. 1997), which represent a
tremendous challenge for breeders that normally base their statistical genetic
approaches on models developed for diploid organisms.
A summary of the genetic characteristics of the Saccharum species and the
‘‘Saccharum complex’’ is shown in Table 5.1.
As a relatively recently domesticated species, sugarcane exhibits little of the
available genetic diversity having been incorporated or actively analyzed for
introgression into domesticated varieties (Dillon et al. 2007; OGTR 2011;
Sreenivasan et al. 1987), and breeding programs in the early 1900s focused on
hybridization of S. officinarum clones, but quickly progressed to interspecific
crosses incorporating S. spontaneum. This resulted in improved agronomic traits,
such as tilling, stand and trashiness abilities, ratooning and disease resistance, but
required a backcrossing program to S. officinarum, called ‘‘nobilization,’’ to elevate the sucrose content (Dillon et al. 2007; Edmé et al. 2005). Since then, the
majority of breeding programs have focused on intercrossing between the hybrids,
though in recent decades the larger increases in genetic gains have been made by
incorporating more diverse germplasm into the cultivated backgrounds (Edmé
et al. 2005; Dillon et al. 2007) not only to increase sucrose production, but also to
diversify into other alternative products to regain profitability.
As a C4 carbohydrate metabolism plant having a perennial life cycle, sugarcane
is one of the most productive cultivated plants. Apart from producing sugar, this
crop has gained increased attention because of its importance as a biofuel source
among other value-added products developed from sugarcane biopharming using
molecular approaches. Nevertheless, sugarcane has one of the most complex
genomes among cultivated plants, which has long hampered the development of
crucial areas such as genetics to support breeding for crop improvement programs.
With the advent of molecular techniques, the sugarcane genome has become less
mysterious, although its complexity has still been confirmed in many aspects
(D’Hont et al. 2008).
In this chapter, we review the current status of sugarcane as a potential
biofactory focusing particularly on the production of pharmaceutical proteins,
biopolymers, and alternative carbohydrates; topics related to the use of sugarcane
for bioenergy generation have been thoroughly addressed elsewhere (Arruda 2012;
de Siqueira et al. 2013; Kuan et al. 2013; Vermerris 2011) and therefore will not be
discussed herein.
5 Sugarcane as a Novel Biofactory: Potentialities and Challenges
131