Environmental Engineering Reference
In-Depth Information
species, are also potential bioenergy crops. The poplar genome has provided a model genome for
research on wood plant species and their use for bioenergy and other applications.
2.13.6 E
ucalyptuS
Eucalypts are the most planted hardwood tress in tropical and subtropical parts of the world (Henry
2011). Members of this group of more than 700 species are adapted to a wide range of environ-
ments. Eucalypts have high biomass accumulation rates and a tolerance of marginal growing condi-
tions, making them good candidates for the production of wood biomass. Many genomics tools for
eucalypts, including genetic maps and gene and genome sequences have been developed in recent
research (Henry 2011).
2.14 Future ProsPects For use oF GenomIcs In
BIoenerGy ProductIon From Plants
The future of energy crops should see the application of genomics to the discovery and manipula-
tion of genes to create optimally designed energy plants. The efficiency of photosynthesis may
be enhanced by selecting or engineering plants with an optimal metabolism for specific environ-
ments. For example, C
4
pathways of photosynthesis may improve the efficiency of carbon fixa-
tion, especially at high light intensities in warm and dry environments. Plant architecture may
be optimized to capture solar energy and use it to fix and store the carbon at a high density in
tissues that can then be easily harvested and converted to useful bioenergy molecules. Biomass
composition may be selected to best suit available biofuel conversion technologies. For example,
altered lignin content and modified carbohydrate composition are major options. Also, the propor-
tion of cellulose and noncellulosic polysaccharides may be altered. Most importantly, the linkages
between different carbohydrate polymers and between carbohydrate and lignin may be reduced
or altered. Genomics will provide the tools to characterize the genetic control of these key biofuel
traits. Enzymes required in any conversion process could all be produced in the plant to reduce costs
and improve energy efficiency.
Future biomass crops need to be designed for sustainable production with all nutrients being
recycled to the soil. Nitrogen needs to be supplied by the crop itself or by other crops in the rota-
tion. Plants also need to be designed to maximize the value of co-products remaining after energy
extraction. This may be an essential feature of the economics of growing bioenergy crops. Some of
these co-products may be industrial or pharmaceutical products. However, high-value animal feeds
and human food co-products have the advantage of reducing the competition between food and
energy production. Protein residues remaining after conversion of plant carbohydrates to energy
may be significant co-product options. Genomics approaches may allow for analyses of bioenergy
and co-product potential and allow selection or breeding for both characteristics.
Genomics also has the potential to make a major contribution to future bioenergy production
on the basis of the novel production of bioenergy from algae. Algae also have potential as a direct
source of high-value fuel molecules (e.g., alkanes). Thus, algae may also represent an alternative
source of biomass.
reFerences
Bundock PC, Eliott F, Ablett G, Benson AD, Casu RE, Aitken KS, Henry RJ (2009) Targeted SNP discovery in
sugarcane using 454 sequencing.
Plant Biotechnol J
7:347-354
Carpita NC, McCann MC (2008) Maize and sorghum: Genetic resources for bioenergy grasses.
Trends Plant
Sci
13:415-420
Cross M, Waters D, Lee LS, Henry RJ (2008) Endonucleolytic mutation analysis by internal labeling (EMAIL).
Electrophoresis
29:1291-1301
