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Session 2 – Cell Wall, Biomass and Biofuels
S2.8- Investigating biomass digestibility in Brachypodium distachyon
Poppy E. Marriott, Leonardo D. Gomez, Caragh Whitehead and Simon J. McQueen-
Mason
CNAP, Department of Biology, University of York, York. YO10 5DD. UK
pm518@york.ac.uk
Abstract
Lignocellulosic biomass is largely composed of polysaccharides which can be broken
down to produce sugars for the production of ethanol through fermentation. This
bioethanol could provide a sustainable replacement for fossil fuel derived transportation
fuels. However, lignocellulose is extremely resistant to digestion and converting it to
fermentable sugars requires energetic pretreatment and expensive enzyme applications.
To make second generation bioethanol a commercial reality we therefore need to
improve the conversion efficiency. One way to achieve this is by producing plants with
more digestible lignocellulose. This project involves a forward genetic screen with the
model grass, Brachypodium distachyon, to identify plants with an alteration in digestibility
from large, randomly mutated populations. Such a large scale screen requires a high
throughput approach and at the University of York an analytical platform has been
developed that can perform saccharification analysis in a 96-well plate format. The
system can reliably detect differences in the saccharification of plant tissues and is able
to rapidly process large numbers of samples with a minimum amount of human
intervention.
Two chemically mutagenised populations were screened (from INRA and the USDA) and
a relatively large amount of variation in sugar release was identified (up to +70% and -
50% compared to WT). Mutants with a significant difference in sugar release in
comparison to WT were isolated and saccharification of the offspring was determined to
test for heritability of the trait. Plants with heritable mutations will be taken forward for in
depth cell wall analysis to understand the effect of the mutation on the structure and
digestibility of the cell wall. Mapping of the mutations will also be undertaken in order to
identify genes involved in the phenotypic variation. This will provide novel genetic
markers to aid in selection of the best genotypes for industrial production of bioethanol.
References
Gomez LD, Whitehead C, Barakate A, et al. (2010) Automated saccharification assay for
determination of digestibility in plant materials. Biotechnology for Biofuels 3: 23.
Gomez LD, Bristow JK, Statham ER, McQueen-Mason SJ (2008) Analysis of
saccharification in Brachypodium distachyon stems under mild conditions of hydrolysis.
Biotechnology for Biofuels 178: 61-72.
Abramson M, Shoseyov O, Shani Z (2010) Plant cell wall reconstruction toward improved
lignocellulosic production and processability. Plant Science 178: 61-72
Garvin DF, Gu YQ, Hasterok R, et al. (2008) Development of genetic and genomic
research resources for Brachypodium distachyon, a new model system for grass crop
research. Crop Science 48: S69-S84
Keywords
Brachypodium, Biofuels, lignocellulose, saccharification, genetic screen
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