Overexpression of a Domain of Unknown Function 266-containing protein results in high cellulose content, reduced recalcitrance, and enhanced plant growth in the bioenergy cropPopulus.
BACKGROUND
Domain of Unknown Function 266 (DUF266) is a plant-specific domain. DUF266-containing proteins (DUF266 proteins) have been categorized as 'not classified glycosyltransferases (GTnc)' due to amino acid similarity with GTs. However, little is known about the function of DUF266 proteins.


RESULTS
Phylogenetic analysis revealed that DUF266 proteins are only present in the land plants including moss and lycophyte. We report the functional characterization of one member of DUF266 proteins inPopulus,PdDUF266A.PdDUF266Awas ubiquitously expressed with high abundance in the xylem. InPopulustransgenic plants overexpressingPdDUF266A(OXPdDUF266A), the glucose and cellulose contents were significantly higher, while the lignin content was lower than that in the wild type. Degree of polymerization of cellulose inOXPdDUF266Atransgenic plants was also higher, whereas cellulose crystallinity index remained unchanged. Gene expression analysis indicated that cellulose biosynthesis-related genes such asCESAandSUSYwere upregulated in mature leaf and xylem ofOXPdDUF266Atransgenic plants. Moreover,PdDUF266Aoverexpression resulted in an increase of biomass production. Their glucose contents and biomass phenotypes were further validated via heterologous expression ofPdDUF266Ain Arabidopsis. Results from saccharification treatment demonstrated that the rate of sugar release was increased by approximately 38% in theOXPdDUF266Atransgenic plants.


CONCLUSIONS
These results suggest that the overexpression ofPdDUF266Acan increase cellulose content, reduce recalcitrance, and enhance biomass production, and thatPdDUF266Ais a promising target for genetic manipulation for biofuel production.
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.
Yongil
Y
Yang
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.|UT-ORNL Joint Institute for Biological Science, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.
Chang Geun
CG
Yoo
Department of Biochemistry & Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996 USA.
Hao-Bo
HB
Guo
ArborGen Inc., Ridgeville, SC 29472 USA.
William
W
Rottmann
ArborGen Inc., Ridgeville, SC 29472 USA.
Kimberly A
KA
Winkeler
ArborGen Inc., Ridgeville, SC 29472 USA.
Cassandra M
CM
Collins
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.
Lee E
LE
Gunter
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.
Sara S
SS
Jawdy
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.
Xiaohan
X
Yang
Department of Biochemistry & Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996 USA.
Hong
H
Guo
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.|UT-ORNL Joint Institute for Biological Science, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.
Yunqiao
Y
Pu
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.|UT-ORNL Joint Institute for Biological Science, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.|Department of Chemical and Biomolecular Engineering & Department of Forestry, Wildlife, and Fisheries, University of Tennessee, Knoxville, TN 37996 USA.
Arthur J
AJ
Ragauskas
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.
Gerald A
GA
Tuskan
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA.
Jin-Gui
0000-0002-1752-4201
JG
Chen
Biofuel; Biomass; Cell wall; Cellulose; DUF266; Populus; Recalcitrance; Sugar release