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

Suppression of CINNAMOYL-CoA REDUCTASE increases the level of monolignol ferulates incorporated into maize lignins

Rebecca A. Smith; Cynthia L. Cass; Mona Mazaheri; Rajandeep S. Sekhon; Marlies Heckwolf; Heidi Kaeppler; Natalia de Leon; Shawn D. Mansfield; Shawn M. Kaeppler; John C. Sedbrook; Steven D. Karlen; John Ralph

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2017

Background The cell wall polymer lignin provides structural support and rigidity to plant cell walls, and therefore to the plant body. However, the recalcitrance associated with lignin impedes the extraction of polysaccharides from the cell wall to make plant-based biofuels and biomaterials. The cell wall digestibility can be improved by introducing labile ester bonds into the lignin backbone that can be easily broken under mild base treatment at room temperature. The FERULOYL-CoA MONOLIGNOL TRANSFERASE (FMT) enzyme, which may be naturally found in many plants, uses feruloyl-CoA and monolignols to synthesize the ester-linked monolignol ferulate conjugates. A mutation in the first lignin-specific biosynthetic enzyme, CINNAMOYL-CoA REDUCTASE (CCR), results in an increase in the intracellular pool of feruloyl-CoA. Results Maize (Zea mays) has a native putative FMT enzyme, and its ccr mutants produce an increased pool of feruloyl-CoA that can be used for conversion to monolignol ferulate conjugates. The decreased lignin content and monomers did not, however, impact the plant growth or biomass. The increase in monolignol conjugates correlated with an improvement in the digestibility of maize stem rind tissue. Conclusions Together, increased monolignol ferulates and improved digestibility in ccr1 mutant plants suggests that they may be superior biofuel crops.

The terpene synthase gene family in Tripterygium wilfordii harbors a labdane-type diterpene synthase among the monoterpene synthase TPS-b subfamily

Nikolaj L. Hansen; Allison M. Heskes; Britta Hamberger; Carl E. Olsen; Björn M. Hallstrom; Johan Andersen-Ranberg; Björn Hamberger

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2017

Tripterygium wilfordii (Celastraceae) is a medicinal plant with anti-inflammatory and immunosuppressive properties. Identification of a vast array of unusual sesquiterpenoids, diterpenoids and triterpenoids in T. wilfordii has spurred investigations of their pharmacological properties. The tri-epoxide lactone triptolide was the first of many diterpenoids identified, attracting interest due to the spectrum of bioactivities. To probe the genetic underpinning of diterpenoid diversity, an expansion of the class II diterpene synthase (diTPS) family was recently identified in a leaf transcriptome. Following detection of triptolide and simple diterpene scaffolds in the root, we sequenced and mined the root transcriptome. This allowed identification of the root-specific complement of TPSs and an expansion in the class I diTPS family. Functional characterization of the class II diTPSs established their activities in the formation of four C-20 diphosphate intermediates, precursors of both generalized and specialized metabolism and a novel scaffold for Celastraceae. Functional pairs of the class I and II enzymes resulted in formation of three scaffolds, accounting for some of the terpenoid diversity found in T. wilfordii. Absence of activity forming abietane-type diterpenes encouraged further testing of TPSs outside the canonical class I diTPS family. TwTPS27, close relative of mono-TPSs, was found to couple with TwTPS9, converting normal-copalyl diphosphate to miltiradiene. The phylogenetic distance to established diTPSs indicates neo-functionalization of TwTPS27 into a diTPS, a function not previously observed in the TPS-b subfamily. This example of evolutionary convergence expands the functionality of TPSs in the TPS-b family and may contribute miltiradiene to the diterpenoids of T. wilfordii. This article is protected by copyright. All rights reserved.

TIPS: a system for automated image-based phenotyping of maize tassels

Joseph L. Gage; Nathan D. Miller; Edgar P. Spalding; Shawn M. Kaeppler; Natalia de Leon

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2017

Background: The maize male inflorescence (tassel) produces pollen necessary for reproduction and commercial grain production of maize. The size of the tassel has been linked to factors affecting grain yield, so understanding the genetic control of tassel architecture is an important goal. Tassels are fragile and deform easily after removal from the plant, necessitating rapid measurement of any shape characteristics that cannot be retained during storage. Some morphological characteristics of tassels such as curvature and compactness are difficult to quantify using traditional methods, but can be quantified by image-based phenotyping tools. These constraints necessitate the development of an efficient method for capturing natural-state tassel morphology and complementary automated analytical meth- ods that can quickly and reproducibly quantify traits of interest such as height, spread, and branch number. Results: This paper presents the Tassel Image-based Phenotyping System (TIPS), which provides a platform for imaging tassels in the field immediately following removal from the plant. TIPS consists of custom methods that can quantify morphological traits from profile images of freshly harvested tassels acquired with a standard digital camera in a field-deployable light shelter. Correlations between manually measured traits (tassel weight, tassel length, spike length, and branch number) and image-based measurements ranged from 0.66 to 0.89. Additional tassel characteris- tics quantified by image analysis included some that cannot be quantified manually, such as curvature, compactness, fractal dimension, skeleton length, and perimeter. TIPS was used to measure tassel phenotypes of 3530 individual tassels from 749 diverse inbred lines that represent the diversity of tassel morphology found in modern breeding and academic research programs. Repeatability ranged from 0.85 to 0.92 for manually measured phenotypes, from 0.77 to 0.83 for the same traits measured by image-based methods, and from 0.49 to 0.81 for traits that can only be measured by image analysis. Conclusions: TIPS allows morphological features of maize tassels to be quantified automatically, with minimal disturbance, at a scale that supports population-level studies. TIPS is expected to accelerate the discovery of associa- tions between genetic loci and tassel morphology characteristics, and can be applied to maize breeding programs to increase productivity with lower resource commitment.

Total biosynthesis of the cyclic AMP booster forskolin from Coleus forskohlii

Irini Pateraki; Johan Andersen-Ranberg; Niels Bjerg Jensen; Sileshi Gizachew Wubshet; Allison Maree Heskes; Victor Forman; Björn Hallström; Britta Hamberger; Mohammed Saddik Motawia; Carl Erik Olsen; Dan Staerk; Jørgen Hansen; Birger Lindberg Møller; Björn Hamberger

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2017

Forskolin is a unique structurally complex labdane type diterpenoid used in the treatment of glaucoma and heart failure based on its activity as a cyclic AMP booster. Commercial production of forskolin relies exclusively on extraction from its only known natural source, the plant Coleus forskohlii, in which forskolin accumulates in the root cork. Here we report the discovery of five cytochrome P450s and two acetyltransferases which catalyze a cascade of reactions converting the forskolin precursor 13R-manoyl oxide into forskolin and a diverse array of additional labdane-type diterpenoids. A minimal set of three P450s in combination with a single acetyl transferase was identified that catalyzes the conversion of 13R-manoyl oxide into forskolin as demonstrated by transient expression in Nicotiana benthamiana. The entire pathway for forskolin production from glucose encompassing expression of nine genes was stably integrated into Saccharomyces cerevisiae and afforded forskolin titers of 40 mg/L.

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