title: Recombinant cellulase accumulation in the leaves of mature, vegetatively propagated transgenic sugarcane.
abstract: The cost of enzymes that hydrolyse lignocellulosic substrates to fermentable sugars needs to be reduced to make cellulosic ethanol a cost-competitive liquid transport fuel. Sugarcane is a perennial crop and the successful integration of cellulase transgenes into the sugarcane production system requires that transgene expression is stable in the ratoon. Herein, we compared the accumulation of recombinant fungal cellobiohydrolase I (CBH I), fungal cellobiohydrolase II (CBH II), and bacterial endoglucanase (EG) in the leaves of mature, initial transgenic sugarcane plants and their mature ratoon. Mature ratoon events containing equivalent or elevated levels of active CBH I, CBH II, and EG in the leaves were identified. Further, we have demonstrated that recombinant fungal CBH I and CBH II can resist proteolysis during sugarcane leaf senescence, while bacterial EG cannot. These results demonstrate the stability of cellulase enzyme transgene expression in transgenic sugarcane and the utility of sugarcane as a biofactory crop for production of cellulases.
authors.affiliation: Syngenta Centre for Sugarcane Biofuels Development, Centre for Tropical Crops and Biocommodities, Queensland University of Technology, 2 George Street, Brisbane, QLD, 4001, Australia, md.harrison@qut.edu.au.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Harrison
authors.forename: R Jason
authors.initials: RJ
authors.lastname: Geijskes
authors.forename: Robyn
authors.initials: R
authors.lastname: Lloyd
authors.forename: Stacy
authors.initials: S
authors.lastname: Miles
authors.forename: Anthony
authors.initials: A
authors.lastname: Palupe
authors.forename: Manuel B
authors.initials: MB
authors.lastname: Sainz
authors.forename: James L
authors.initials: JL
authors.lastname: Dale
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D044602:Cellulases / Q000235:genetics* / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology; D030821:Plants, Genetically Modified / Q000201:enzymology*; D059748:Proteolysis; D031786:Saccharum / Q000201:enzymology / Q000235:genetics*; D019076:Transgenes
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D044602:Cellulases