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

Designer lignins: harnessing the plasticity of lignification

Yaseen Mottiar; Ruben Vanholme; Wout Boerjan; John Ralph; Shawn D. Mansfield

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2016

Lignin is a complex polyphenolic constituent of plant secondary cell walls. Inspired largely by the recalcitrance of lignin to biomass processing, plant engineering efforts have routinely sought to alter lignin quantity, composition, and structure by exploiting the inherent plasticity of lignin biosynthesis. More recently, researchers are attempting to strategically design plants for increased degradability by incorporating monomers that lead to a lower degree of polymerisation, reduced hydrophobicity, fewer bonds to other cell wall constituents, or novel chemically labile linkages in the polymer backbone. In addition, the incorporation of value-added structures could help valorise lignin. Designer lignins may satisfy the biological requirement for lignification in plants while improving the overall efficiency of biomass utilisation.

Draft assembly of elite inbred line PH207 provides insights into genomic and transcriptome diversity in maize

Candice N. Hirsch; Cory D. Hirsch; Alex B. Brohammer; Megan J. Bowman; Ilya Soifer; Omer Barad; Doron Shem-Tov; Kobi Baruch; Fei Lu; Alvaro G. Hernandez; Christopher J. Fields; Chris L. Wright; Klaus Koehler; Nathan M. Springer; Edward Buckler; Robin Buell; Natalia de Leon; Shawn M. Kaeppler; Kevin L. Childs; Mark A. Mikel

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2016

Intense artificial selection over the last 100 years has produced elite maize (Zea mays) inbred lines that combine to produce high-yielding hybrids. To further our understanding of how genome and transcriptome variation contribute to the production of high-yielding hybrids, we generated a draft genome assembly of the inbred line PH207 to complement and compare with the existing B73 reference sequence. B73 is a founder of the Stiff Stalk germplasm pool, while PH207 is a founder of Iodent germplasm, both of which have contributed substantially to the production of temperate commercial maize and are combined to make heterotic hybrids. Comparison of these two assemblies revealed over 2,500 genes present in only one of the two genotypes and 136 gene families that have undergone extensive expansion or contraction. Transcriptome profiling revealed extensive expression variation, with as many as 10,564 differentially expressed transcripts and 7,128 transcripts expressed in only one of the two genotypes in a single tissue. Genotype-specific genes were more likely to have tissue/condition-specific expression and lower transcript abundance. The availability of a high-quality genome assembly for the elite maize inbred PH207 expands our knowledge of the breadth of natural genome and transcriptome variation in elite maize inbred lines across heterotic pools.

Dynamics of biomass partitioning, stem gene expression, cell wall biosynthesis, and sucrose accumulation during development of Sorghum bicolor

Brian McKinley; William Rooney; Curtis Wilkerson; John Mullet

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2016

Biomass accumulated preferentially in leaves of the sweet sorghum Della until floral initiation, then stems until anthesis, followed by panicles until grain maturity, and apical tillers. Sorghum stem RNA-seq transcriptome profiles and composition data were collected for ~100 days of development beginning at floral initiation. The analysis identified >200 differentially expressed genes involved in stem growth, cell wall biology, and sucrose accumulation. Genes encoding expansins and xyloglucan endotransglucosylase/hydrolases were differentially expressed in growing stem internodes. Genes encoding enzymes involved in the synthesis of cellulose, lignin, and glucuronoarabinoxylan were expressed at elevated levels in stems until ~7 days before anthesis and then down regulated. CESA genes involved in primary and secondary cell wall synthesis showed different temporal patterns of expression. Following floral initiation, the level of sucrose and other non-structural carbohydrates increased to ~50% of the stem's dry weight. Stem sucrose accumulation was inversely correlated with >100-fold down-regulation of SbVIN1, a gene encoding a vacuolar invertase. Accumulation of stem sucrose was also correlated with cessation of leaf and stem growth at anthesis, decreased expression of genes involved in stem cell wall synthesis, and ~10-fold lower expression of SbSUS4, a gene encoding sucrose synthase that generates UDP-glucose from sucrose for cell wall biosynthesis. Genes for mixed linkage glucan synthesis (CSLF) and turnover were expressed at high levels in stems throughout development. Overall, the stem transcription profile resource and the genes and regulatory dynamics identified in this study will be useful for engineering sorghum stem composition for improved conversion to biofuels and bioproducts. This article is protected by copyright. All rights reserved.

Effective alkaline metal-catalyzed oxidative delignification of hybrid poplar

Aditya Bhalla; Namita Bansal; Ryan J. Stoklosa; Mackenzie Fountain; John Ralph; David B. Hodge; Eric L. Hegg

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2016

Strategies to improve copper-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment of hybrid poplar were investigated. These improvements included a combination of increasing hydrolysis yields, while simultaneously decreasing process inputs through (i) more efficient utilization of H2O2 and (ii) the addition of an alkaline extraction step prior to the metal-catalyzed AHP pretreatment. We hypothesized that utilizing this improved process could substantially lower the chemical inputs needed during pretreatment.

Enhancing digestibility and ethanol yield of Populus wood via expression of an engineered monolignol 4-O-methyltransferase

Yuanheng Cai; Kewei Zhang; Hoon Kim; Guichuan Hou; Xuebin Zhang; Huijun Yang; Huan Feng; Lisa Miller; John Ralph; Chang-Jun Liu

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2016

Producing cellulosic biofuels and bio-based chemicals from woody biomass is impeded by the presence of lignin polymer in the plant cell wall. Manipulating the monolignol biosynthetic pathway offers a promising approach to improved processability, but often impairs plant growth and development. Here, we show that expressing an engineered 4-O-methyl- transferase that chemically modifies the phenolic moiety of lignin monomeric precursors, thus preventing their incorporation into the lignin polymer, substantially alters hybrid aspens’ lignin content and structure. Woody biomass derived from the transgenic aspens shows a 62% increase in the release of simple sugars and up to a 49% increase in the yield of ethanol when the woody biomass is subjected to enzymatic digestion and yeast-mediated fermentation. Moreover, the cell wall structural changes do not affect growth and biomass production of the trees. Our study provides a useful strategy for tailoring woody biomass for bio-based applications.

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