title: Ethanol inducible expression of a mesophilic cellulase avoids adverse effects on plant development.
abstract: BACKGROUND
  Plant-produced biomass-degrading enzymes are promising tools for the processing of lignocellulose to fermentable sugars. A major limitation of in planta production is that high-level expression of such enzymes could potentially affect the structure and integrity of the plant cell wall and negatively influence plant growth and development.
  
  
  RESULTS
  Here, we evaluate the impact on tobacco plant development of constitutive versus alcohol-inducible expression of the endoglucanase TrCel5A from the mesophilic fungus Trichoderma reesei. Using this system, we are able to demonstrate that constitutive expression of the enzyme, controlled by the doubled Cauliflower Mosaic Virus promoter, leads to lower cellulose content of the plant combined with severe effects on plant growth. However, using an alcohol-inducible expression of the endoglucanase in the plant leaves, we achieved similar enzymatic expression levels with no changes in the crystalline cellulose content.
  
  
  CONCLUSIONS
  We were able to produce significant amounts of cellulase in the plant leaves without detrimental effects to plant development. These results demonstrate the potential feasibility of an inducible expression system for producing biomass degrading enzymes in plants.
authors.affiliation: Institute for Molecular Biotechnology (Biology VII), RWTH Aachen University, Worringerweg 1, Aachen, 52074, Germany. commandeur@molbiotech.rwth-aachen.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Klose
authors.forename: Markus
authors.initials: M
authors.lastname: Günl
authors.forename: Björn
authors.initials: B
authors.lastname: Usadel
authors.forename: Rainer
authors.initials: R
authors.lastname: Fischer
authors.forename: Ulrich
authors.initials: U
authors.lastname: Commandeur