title: Down-Regulation ofKORRIGAN-Like Endo-β-1,4-Glucanase Genes Impacts Carbon Partitioning, Mycorrhizal Colonization and Biomass Production inPopulus.
abstract: A greater understanding of the genetic regulation of plant cell wall remodeling and the impact of modified cell walls on plant performance is important for the development of sustainable biofuel crops. Here, we studied the impact of down-regulating KORRIGAN-like cell wall biosynthesis genes, belonging to the endo-β-1,4-glucanase gene family, onPopulusgrowth, metabolism and the ability to interact with symbiotic microbes. The reductions in cellulose content and lignin syringyl-to-guaiacyl unit ratio, and increase in cellulose crystallinity of cell walls ofPdKORRNAi plants corroborated the functional role of PdKOR in cell wall biosynthesis. Altered metabolism and reduced growth characteristics of RNAi plants revealed new implications on carbon allocation and partitioning. The distinctive metabolome phenotype comprised of a higher phenolic and salicylic acid content, and reduced lignin, shikimic acid and maleic acid content relative to control. Plant sustainability implications of modified cell walls on beneficial plant-microbe interactions were explored via co-culture with an ectomycorrhizal fungus,Laccaria bicolor. A significant increase in the mycorrhization rate was observed in transgenic plants, leading to measurable beneficial growth effects. These findings present new evidence for functional interconnectedness of cellulose biosynthesis pathway, metabolism and mycorrhizal association in plants, and further emphasize the consideration of the sustainability implications of plant trait improvement efforts.
authors.affiliation: BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge TN, USA.
authors.forename: Udaya C
authors.initials: UC
authors.lastname: Kalluri
authors.affiliation: BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge TN, USA.
authors.forename: Raja S
authors.initials: RS
authors.lastname: Payyavula
authors.affiliation: BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge TN, USA.
authors.forename: Jessy L
authors.initials: JL
authors.lastname: Labbé
authors.affiliation: BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge TN, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Engle
authors.affiliation: BioEnergy Science Center, School of Chemistry and Biochemistry, Institute of Paper Science and Technology, Georgia Institute of Technology, Atlanta GA, USA.
authors.forename: Garima
authors.initials: G
authors.lastname: Bali
authors.affiliation: BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge TN, USA.
authors.forename: Sara S
authors.initials: SS
authors.lastname: Jawdy
authors.affiliation: The Biosciences Center, National Renewable Energy Laboratory, Golden CO, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Sykes
authors.affiliation: The Biosciences Center, National Renewable Energy Laboratory, Golden CO, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Davis
authors.affiliation: Oak Ridge National Laboratory - Department of Chemical and Biomolecular Engineering and Department of Forestry, Wildlife and Fisheries, University of Tennessee, Knoxville TN, USA.
authors.forename: Arthur
authors.initials: A
authors.lastname: Ragauskas
authors.affiliation: BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge TN, USA.
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Tuskan
authors.affiliation: BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge TN, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Tschaplinski
keywords: 4-glucanase; Populus; biomass; carbon partitioning and allocation; cellulose; endo-β-1; microbe; mycorrhiza; plant cell wall