Silencing () in Switchgrass ( L.) Improves Lignocellulosic Biofuel Production.

Switchgrass ( L.) is a lignocellulosic perennial grass with great potential in bioenergy field. Lignocellulosic bioenergy crops are mostly resistant to cell wall deconstruction, and therefore yield suboptimal levels of biofuel.

Correction to: Multiple levers for overcoming the recalcitrance of lignocellulosic biomass.

[This corrects the article DOI: 10.1186/s13068-019-1353-7.].

Multiple levers for overcoming the recalcitrance of lignocellulosic biomass.

Background: The recalcitrance of cellulosic biomass is widely recognized as a key barrier to cost-effective biological processing to fuels and chemicals, but the relative impacts of physical, chemical and genetic interventions to improve biomass processing singly and in combination have yet to be evaluated systematically. Solubilization of plant cell walls can be enhanced by non-biological augmentation including physical cotreatment and thermochemical pretreatment, the choice of biocatalyst, the choice of plant feedstock, genetic engineering of plants, and choosing feedstocks that are less recalcitrant natural variants. A two-tiered combinatoric investigation of lignocellulosic biomass deconstruction was undertaken with three biocatalysts (, Novozymes Cellic Ctec2 and Htec2), three transgenic switchgrass plant lines (COMT, MYB4, GAUT4) and their respective nontransgenic controls, two natural variants, and augmentation of biological attack using either mechanical cotreatment or cosolvent-enhanced lignocellulosic fractionation (CELF) pretreatment.

Functional Analysis of Cellulose Synthase and Genes in Switchgrass () by Overexpression and RNAi-Mediated Gene Silencing.

Switchgrass ( L.) is a leading lignocellulosic bioenergy feedstock. Cellulose is a major component of the plant cell walls and the primary substrate for saccharification.

Dual Utilization of Medicinal and Aromatic Crops as Bioenergy Feedstocks.

Dual production of biofuels and chemicals can increase the economic value of lignocellulosic bioenergy feedstocks. We compared the bioenergy potential of several essential oil (EO) crops with switchgrass ( Panicum virgatum L.), a crop chosen to benchmark biomass and lignocellulosic biofuel production.

Switchgrass ( L.) promoters for green tissue-specific expression of the transcription factor for reduced-recalcitrance transgenic switchgrass.

Background: Genetic engineering of switchgrass ( L.) for reduced cell wall recalcitrance and improved biofuel production has been a long pursued goal. Up to now, constitutive promoters have been used to direct the expression of cell wall biosynthesis genes toward attaining that goal.

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. 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.

Transgenic miR156 switchgrass in the field: growth, recalcitrance and rust susceptibility.

Sustainable utilization of lignocellulosic perennial grass feedstocks will be enabled by high biomass production and optimized cell wall chemistry for efficient conversion into biofuels. MicroRNAs are regulatory elements that modulate the expression of genes involved in various biological functions in plants, including growth and development. In greenhouse studies, overexpressing a microRNA (miR156) gene in switchgrass had dramatic effects on plant architecture and flowering, which appeared to be driven by transgene expression levels.

Study of traits and recalcitrance reduction of field-grown down-regulated switchgrass.

Background: The native recalcitrance of plants hinders the biomass conversion process using current biorefinery techniques. Down-regulation of the caffeic acid -methyltransferase () gene in the lignin biosynthesis pathway of switchgrass reduced the thermochemical and biochemical conversion recalcitrance of biomass. Due to potential environmental influences on lignin biosynthesis and deposition, studying the consequences of physicochemical changes in field-grown plants without pretreatment is essential to evaluate the performance of lignin-altered plants.

Transgenic switchgrass (Panicum virgatum L.) targeted for reduced recalcitrance to bioconversion: a 2-year comparative analysis of field-grown lines modified for target gene or genetic element expression.

Transgenic Panicum virgatum L. silencing (KD) or overexpressing (OE) specific genes or a small RNA (GAUT4-KD, miRNA156-OE, MYB4-OE, COMT-KD and FPGS-KD) was grown in the field and aerial tissue analysed for biofuel production traits. Clones representing independent transgenic lines were established and senesced tissue was sampled after year 1 and 2 growth cycles.

Downregulation of a UDP-Arabinomutase Gene in Switchgrass ( L.) Results in Increased Cell Wall Lignin While Reducing Arabinose-Glycans.

Switchgrass ( L.) is a C perennial prairie grass and a dedicated feedstock for lignocellulosic biofuels. Saccharification and biofuel yields are inhibited by the plant cell wall's natural recalcitrance against enzymatic degradation.

Effects of Produced Water on Soil Characteristics, Plant Biomass, and Secondary Metabolites.

The Powder River Basin in Wyoming and Montana contains the United States' largest coal reserve. The area produces large amounts of natural gas through extraction from water-saturated coalbeds. Determining the impacts of coalbed natural gas-produced efflux water on crops is important when considering its potential use as supplemental irrigation water.

Integrated metagenomics and metatranscriptomics analyses of root-associated soil from transgenic switchgrass.

The benefits of using transgenic switchgrass with decreased levels of caffeic acid 3-O-methyltransferase (COMT) as biomass feedstock have been clearly demonstrated. However, its effect on the soil microbial community has not been assessed. Here we report metagenomic and metatranscriptomic analyses of root-associated soil from COMT switchgrass compared with nontransgenic counterparts.

Altered lignin biosynthesis using biotechnology to improve lignocellulosic biofuel feedstocks.

Lignocellulosic feedstocks can be converted to biofuels, which can conceivably replace a large fraction of fossil fuels currently used for transformation. However, lignin, a prominent constituent of secondary cell walls, is an impediment to the conversion of cell walls to fuel: the recalcitrance problem. Biomass pretreatment for removing lignin is the most expensive step in the production of lignocellulosic biofuels.

Two-year field analysis of reduced recalcitrance transgenic switchgrass.

Switchgrass (Panicum virgatum L.) is a leading candidate for a dedicated lignocellulosic biofuel feedstock owing to its high biomass production, wide adaptation and low agronomic input requirements. Lignin in cell walls of switchgrass, and other lignocellulosic feedstocks, severely limits the accessibility of cell wall carbohydrates to enzymatic breakdown into fermentable sugars and subsequently biofuels.

Gateway-compatible vectors for high-throughput gene functional analysis in switchgrass (Panicum virgatum L.) and other monocot species.

Switchgrass (Panicum virgatum L.) is a C4 perennial grass and has been identified as a potential bioenergy crop for cellulosic ethanol because of its rapid growth rate, nutrient use efficiency and widespread distribution throughout North America. The improvement of bioenergy feedstocks is needed to make cellulosic ethanol economically feasible, and genetic engineering of switchgrass is a promising approach towards this goal.

A high-throughput transient gene expression system for switchgrass (Panicum virgatum L.) seedlings.

Background: Grasses are relatively recalcitrant to genetic transformation in comparison to certain dicotyledons, yet they constitute some of the most important biofuel crops. Genetic transformation of switchgrass (Panicum virgatum L.) has previously been reported after cocultivation of explants with Agrobacterium and biolistics of embryogenic calli.