Highlights

GLBRC's Publications

Highlights

Our researchers consistently turn out new and innovative research that can lead to publications and new technology. On this page we'll highlight new research publications and/or activities in the GLBRC that underscore the great work that our researchers are doing.

Cellulosic bioenergy offers environmental benefits not available from other biofuels, but requires substantial amounts of land and creates the potential for environmental harm. It is therefore important to understand how different bioenergy crop and management choices will simultaneously affect climate mitigation, biodiversity, reactive nitrogen loss, and water use in future biofuel landscapes.

To improve bioenergy crop composition and yield, we seek to understand activation of the unfolded protein response (UPR) and its impact on the ability of plant cells to accumulate easily digestible carbohydrates such as mixed-linkage glucan (MLG). Here we identify a Brachypodium UPR transcription factor, UPR genes responsive to chemical or heat stress, and impacts of heat stress on MLG accumulation.

Bioenergy sorghum accumulates 75% of shoot biomass in its stem internodes. To identify genes and molecular mechanisms that modulate the extent of internode growth, we conducted microscopic and transcriptomic analyses of four successive sub-apical vegetative internodes representing different stages of internode development of the bioenergy sorghum genotype R.07020.

To develop bioenergy crops that produce extra lipids for extraction as oil biofuel, we examined whether lipid transport complexes of plants with different lipid acyl composition have diverged in their function. 

We used transposon sequencing (Tn-seq) to identify essential genes in the bacterium Rhodobacter sphaeroides under several growth conditions. We then used that data to evaluate and refine an existing genome-scale metabolic model, providing more precise systems-level understanding of the diverse metabolic lifestyles of this bacterium. 

To better understand flowering time control in temperate grasses, we sought to identify which genes prevent a grass from flowering until it has undergone prolonged cold exposure. After screening for and identifying mutants in the grass species Brachypodium distachyon, we identified a mutant that flowers rapidly without cold exposure, and described and characterized a new gene we named REPRESSOR OF VERNALIZATION1 (RVR1). 

Microbial production of lipids in high yield presents a significant challenge, often falling short of what can be theoretically obtained. This study characterized high-lipid mutant variants of Rhodobacter sphaeroides and showed that alterations to the bacterial cell envelope can result in increased accumulation of lipids relative to the parent strain.

Researchers show that the three main components of plant biomass can be converted to high value products in economically favorable yields when using the solvent gamma-valerolactone (GVL) to break apart the biomass. Researchers show that the three main components of plant biomass can be converted to high value products in economically favorable yields when using the solvent gamma-valerolactone (GVL) to break apart the biomass. 

Introducing ester linkages into the lignin polymer backbone that decrease biomass recalcitrance in poplar has the potential to reduce the energy and/or amount of ionic liquids required for effective pretreatment.

Pretreating lignocellulosic biomass using microbes such as C. thermocellum enables a one-pot process for breaking down sugars and fermenting those sugars for fuel and chemicals. In this study, we examined the bacterium’s efficiency in breaking down cellulose in industrially relevant pretreated biomass, finding that pretreatments that remove both lignin and hemicellulose can help improve the specific activity of the bacterium’s cellulosomal enzymes.

In this study, we examined features of a lignin biosynthetic mutant in maize that we hypothesized could result in an increase in the levels of more readily cleavable ester bonds (“zip-lignin”) in the lignin backbone. The maize ccr1 mutant displayed reduced total lignin content with no growth penalties, higher zip-lignin levels, and higher levels of sugar release. 

To help identify better management practices for more productive bioenergy cropping systems, we used two switchgrass sites to investigate the causes of biomass loss over time, and identified plant components contributing to nitrogen (N) loss or retention at different harvest times. 

Depolymerizing lignin, the complex phenolic polymer fortifying plant cell walls, is challenging, making lignin a major barrier to gaining access to stored energy in lignocellulosic materials. Here we reveal unprecedentedly rapid lignin depolymerization and degradation in an ancient fungus-cultivating termite system; we combine laboratory-feeding experiments with step-wise structural and chemical analyses performed while the woody material is digested in this symbiotic system.

Glycoside hydrolases (GH) are enzymes that release sugar from cellulose, hemicellulose, and other polysaccharides. Understanding the specificity of GH enzyme reactions in the context of the plant cell wall is essential to providing more efficient ways to deconstruct plant biomass for biofuels production.

Recovering sugars and lignin from the deconstruction solvent GVL relies on methods that are expensive or may inhibit downstream conversion of sugars to biofuels. A new method examines the use of co-solvents1 and their impact on sugar yield and economics of biofuel production.2

To better understand the development of plant cell walls and to improve strategies for the valorization of lignocellulosics, we identified and quantified 12 degradation products released by lignin depolymerization using newly synthesized standards. 

This study tested whether we can alter cell wall attributes and plant development by augmenting the available soluble sucrose pools. To this end, we overexpressed an exogenous galactinol synthase to alter carbon allocation in hybrid poplar and then examined the effects on plant growth, carbohydrate and lignin content and composition, xylem properties, wood physical characteristics, and transcript abundance of differentially expressed genes.

The degradation of cellulose, the principal component of plant cell walls, is critical to ecosystem functioning and the global carbon cycle. The primary drivers of plant biomass deconstruction are fungi and bacteria found in the soil or associated with plant-eating eukaryotes. 

Native perennial grasslands, which can be planted on marginal lands, are a potential feedstock source for lignocellulosic biofuel production. And yet more information is needed to understand how management practices such as frequency or timing of harvesting can affect their productivity and community composition.

By studying a naturally silenced maize mutant defective in chalcone synthase, a key enzyme involved in the biosynthesis of flavonoids, we demonstrated that levels of tricin-related flavonoids were significantly reduced, resulting in strongly reduced incorporation of tricin into the lignin polymer. These plants also had increased total lignin content and, consequently, demonstrated significantly reduced saccharification.

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