Phylogenetic tree of GAUT Protein Family and gene model, RNAi construct, and relative transcript abundance of GAUT4 in switchgrass, rice and poplar knockdown (KD) lines.

bio engineered↗

DOE OSTI2026

Glycosyl linkage analysis of fractionated cell walls from switchgrass WT and PvGAUT4-KD lines

bio engineered↗

DOE OSTI2026

Glycosyl linkage analysis of fractionated cell walls from P.deltoides WT and PdGAUT4-KD lines.

bio engineered↗

DOE OSTI2018

A New Calmodulin-Binding Protein Expresses in the Context of Secondary Cell Wall Biosynthesis and Impacts Biomass Properties in Populus

Here, a greater understanding of biosynthesis, signaling and regulatory pathways involved in determining stem growth and secondary cell wall chemistry is important for enabling pathway engineering and genetic optimization of biomass properties. The present study describes a new functional role of PdIQD10 , a Populus gene belonging to the IQ67-Domain1 family of IQD genes, in impacting biomass formation and chemistry. Expression studies showed that PdIQD10 has enhanced expression in developing xylem and tension-stressed tissues in Populus deltoides . Molecular dynamics simulation and yeast two-hybrid interaction experiments suggest interactions with two calmodulin proteins, CaM247 and CaM014, supporting the sequence-predicted functional role of the PdIQD10 as a calmodulin-binding protein. PdIQD10 was found to interact with specific Populus isoforms of the Kinesin Light Chain protein family, shown previously to function as microtubule-guided, cargo binding and delivery proteins in Arabidopsis . Subcellular localization studies showed that PdIQD10 localizes in the nucleus and plasma membrane regions. Promoter-binding assays suggest that a known master transcriptional regulator of secondary cell wall biosynthesis (PdWND1B) may be upstream of an HD-ZIP III gene that is in turn upstream of PdIQD10 gene in the transcriptional network. RNAi-mediated downregulation of PdIQD10 expression resulted in plants with altered biomass properties including higher cellulose, wall glucose content and greater biomass quantity. Furthermore, these results present evidence in support of a new functional role for an IQD gene family member, PdIQD10 , in secondary cell wall biosynthesis and biomass formation in Populus.

09 BIOMASS FUELS↗

DOE OSTI2018

A 5-Enolpyruvylshikimate 3-Phosphate Synthase Functions as a Transcriptional Repressor in Populus

Not Available

09 BIOMASS FUELS↗

DOE OSTI2018

Sugar release and growth of biofuel crops are improved by downregulation of pectin biosynthesis

Cell walls in crops and trees have been engineered for production of biofuels and commodity chemicals, but engineered varieties often fail multi-year field trials and are not commercialized. In this paper, we engineered reduced expression of a pectin biosynthesis gene (Galacturonosyltransferase 4, GAUT4) in switchgrass and poplar, and find that this improves biomass yields and sugar release from biomass processing. Both traits were maintained in a 3-year field trial of GAUT4-knockdown switchgrass, with up to sevenfold increased saccharification and ethanol production and sixfold increased biomass yield compared with control plants. We show that GAUT4 is an α-1,4-galacturonosyltransferase that synthesizes homogalacturonan (HG). Downregulation of GAUT4 reduces HG and rhamnogalacturonan II (RGII), reduces wall calcium and boron, and increases extractability of cell wall sugars. Finally, decreased recalcitrance in biomass processing and increased growth are likely due to reduced HG and RGII cross-linking in the cell wall.

09 BIOMASS FUELS↗

DOE OSTI2017

Lignin Exhibits Recalcitrance-Associated Features Following the Consolidated Bioprocessing of Populus trichocarpa Natural Variants

Because cellulosic ethanol production remains cost-prohibitive„ advances in consolidated bioprocessing (CBP) have been directed towards lifting this restriction. CBP reduces the need for added enzymes and can potentially slash ethanol production costs through process integration. Clostridium thermocellum, a CBP microorganism, organizes its enzymes in a multi-enzyme complex - a stark contrast to fungal enzymes. Nonetheless, recalcitrance may limit the extent of biomass deconstruction. Here in this study, six Populus were treated with C. thermocellum (ATCC 27405) and characterized to determine structural changes that resulted from CBP. The 2D HSQC NMR spectra of lignin-enriched residues revealed that higher S/G ratio (2.6) and fewer carbon-carbon interunit linkages (generally 2–5%) were present in the top performing poplar. Furthermore, cellulose degree of polymerization data suggests that C. thermocellum likely circumvents long chain cellulose, while cellulose crystallinity and hemicellulose molecular weight data do not provide a direct indication of features connected to recalcitrance. Hence, C. thermocellum is similarly impacted by the proposed lignin properties that negatively impact biomass deconstruction using fungal enzymes.

59 BASIC BIOLOGICAL SCIENCES↗