Plants

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GLBRC's Plants Research Area

Plants

At the GLBRC, Plants researchers are developing the next generation of biomass-trait-improved crops. Because crops will continue to be grown for food and feed in the future, research focused on enhancing plants with desirable energy traits must be pursued without sacrificing grain yield and quality.

Learn about the Center's research approach

Plants Leadership

Plants Lead

Ralph’s program is aimed at decreasing plant cell wall recalcitrance to processing and improving plant value to the biorefinery, largely by: detailing lignin structure, chemistry, and reactions; delineating the effects of perturbing lignin biosynthetic pathways; ‘redesigning’ lignins in planta to...

Plants Lead

Brandizzi is a professor in the Michigan State University-U.S. Department of Energy (MSU-DOE) Plant Research Laboratory, and brings over 15 years of academic research experience to her role at GLBRC. Prior to coming to Michigan, Brandizzi was an associate professor...

Project Overview

Primary root of live Arabidopsis thaliana seedlings grown with green fluorescence-tagged monolignol probeGLBRC Plants research is highly genomics-focused. Although most plants used in agriculture have been selected for improved production of food or fiber, future bioenergy crops will have different characteristics, including high-energy yield per hectare, ease of conversion to fuels, and agricultural sustainability. Thus, while the Center's long-term efforts focus primarily on dedicated bioenergy crops such as perennial grasses and short-rotation woody species, improving basic traits in all biomass-relevant crops including the grain annuals is a priority.

Plants research projects fall under three general categories:

  • Reducing lignocellulosic biomass recalcitrance through plant cell wall modification
  • Improving the value of the biomass grown for bioenergy production
  • Integrating these and other beneficial traits into bioenergy crops that exhibit improved nutrient use and stress tolerance for sustainable, perennialized production

Plants Publications

A novel pathway for triacylglycerol biosynthesis is responsible for the accumulation of massive quantities of glycerolipids in the surface wax of Bayberry (Myrica pensylvanica) fruit

Jeffrey P. Simpson; John B. Ohlrogge

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2016

Bayberry fruits synthesize an extremely thick and unusual layer of crystalline surface wax that accumulates to 30% of fruit dry weight, the highest reported surface lipid accumulation in plants. The composition is also striking, consisting of completely saturated triacylglycerol, diacylglycerol and monoacylglycerol with palmitate and myristate acyl chains. To gain insight into the unique properties of Bayberry wax synthesis we examined the chemical and morphological development of the wax layer, monitored wax biosynthesis through [14C]-radiolabeling, and sequenced the transcriptome. Radiolabeling identified sn-2 MAG as the first glycerolipid intermediate. The kinetics of [14C]-DAG and [14C]-TAG accumulation and the regiospecificity of their [14C]-acyl chains indicated distinct pools of acyl donors and that final TAG assembly occurs outside of cells. The most highly expressed genes were associated with production of cutin, whereas transcripts for conventional TAG synthesis were >50-fold less abundant. The biochemical and expression data together indicate that Bayberry surface glycerolipids are synthesized by a previously unknown pathway for TAG synthesis that is related to cutin biosynthesis. The combination of a unique surface wax and massive accumulation may aid understanding of how plants produce and secrete non-membrane glycerolipids, and also how to engineer alternative pathways for lipid production in non-seeds.

Accuracy of genomic prediction in switchgrass (Panicum virgatum L.) improved by accounting for linkage disequilibrium

Guillaume P. Ramstein; Joseph Evans; Shawn M. Kaeppler; Robert B. Mitchell; Kenneth P. Vogel; Robin Buell; Michael D. Casler

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2016

Switchgrass is a relatively high-yielding and environmentally sustainable biomass crop, but further genetic gains in biomass yield must be achieved to make it an economically viable bioenergy feedstock. Genomic selection is an attractive technology to generate rapid genetic gains in switchgrass and meet the goals of a substantial displacement of petroleum use with biofuels in the near future. In this study, we empirically assessed prediction procedures for genomic selection in two different populations consisting of 137 and 110 half-sib families of switchgrass, tested in two locations in the United States for three agronomic traits: dry matter yield, plant height and heading date. Marker data was produced for the families' parents by exome capture sequencing, generating up to 141,030 polymorphic markers with available genomic-location and annotation information. We evaluated prediction procedures that varied not only by learning schemes and prediction models, but also by the way the data was preprocessed to account for redundancy in marker information. More complex genomic prediction procedures were generally not significantly more accurate than the simplest procedure, likely due to limited population sizes. Nevertheless, a highly significant gain in prediction accuracy was achieved by transforming the marker data through a marker correlation matrix. Our results suggest that marker-data transformations and, more generally, the account of linkage disequilibrium among markers, offer valuable opportunities for improving prediction procedures in genomic selection. Some of the achieved prediction accuracies should motivate implementation of genomic selection in switchgrass breeding programs./p>.

An essential role of caffeoyl shikimate esterase in monolignol biosynthesis in Medicago truncatula

Chan Ma Ha; Luis Escamilla-Trevino; Juan Carlos Ser Yarce; Hoon Kim; John Ralph; Fang Chen; Richard A. Dixon

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2016

Biochemical and genetic analyses have identified caffeoyl shikimate esterase (CSE) as an enzyme in the monolignol biosynthesis pathway in Arabidopsis thaliana (Vanholme et al., 2013b), although the generality of this finding has been questioned. Here we show the presence of CSE genes and associated enzyme activity in barrel medic (Medicago truncatula, dicot, Leguminosae), poplar (Populus deltoides, dicot, Salicaceae), and switchgrass (Panicum virgatum, monocot, Poaceae). Loss of function of CSE in transposon insertion lines of M. truncatula results in severe dwarfing, altered development, reduction in lignin content, and preferential accumulation of hydroxyphenyl units in lignin, indicating that the CSE enzyme is critical for normal lignification in this species. However, the model grass Brachypodium distachyon and corn (Zea mays) do not possess orthologs of the currently characterized CSE genes, and crude protein extracts from stems of these species exhibit only week esterase activity with caffeoyl shikimate. Our results suggest that the reaction catalyzed by CSE may not be essential for lignification in all plant species. This article is protected by copyright. All rights reserved.

Biosynthesis of the plant cell wall matrix polysaccharide xyloglucan

Markus Pauly; Kenneth Keegstra

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2016

Xyloglucan (XyG) is a matrix polysaccharide that is present in the cell walls of all land plants. It consists of a beta-1,4-linked glucan backbone that is further substituted with xylosyl residues. These xylosyl residues can be further substituted with other glycosyl and nonglycosyl substituents that vary depending on the plant family and specific tissue. Advances in plant mutant isolation and characterization, functional genomics, and DNA sequencing have led to the identification of nearly all transferases and synthases necessary to synthesize XyG. Thus, in terms of the molecular mechanisms of plant cell wall polysaccharide biosynthesis, XyG is the most well understood. However, much remains to be learned about the molecular mechanisms of polysaccharide assembly and the regulation of these processes. Knowledge of the XyG biosynthetic machinery allows the XyG structure to be tailored in planta to ascertain the functions of this polysaccharide and its substituents in plant growth and interactions with the environment. Expected final online publication date for the Annual Review of Plant Biology Volume 67 is April 29, 2016. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.

Cell wall composition and biomass recalcitrance differences within a genotypically diverse set of Brachypodium distachyon inbred lines

Cynthia L. Cass; Anastasiya A. Lavell; Nicholas Santoro; Cliff E. Foster; Steven D. Karlen; Rebecca A. Smith; John Ralph; David F. Garvin; John C. Sedbrook

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2016

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