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Unda F, Mottiar Y, Mahon EL, Karlen SD, Kim KH, Loqué D, Eudes A, Ralph J, Mansfield SD. A new approach to zip-lignin: 3,4-dihydroxybenzoate is compatible with lignification. New Phytol 2022; 235:234-246. [PMID: 35377486 PMCID: PMC9325543 DOI: 10.1111/nph.18136] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/17/2022] [Indexed: 06/02/2023]
Abstract
Renewed interests in the development of bioenergy, biochemicals, and biomaterials have elicited new strategies for engineering the lignin of biomass feedstock plants. This study shows, for the first time, that 3,4-dihydroxybenzoate (DHB) is compatible with the radical coupling reactions that assemble polymeric lignin in plants. We introduced a bacterial 3-dehydroshikimate dehydratase into hybrid poplar (Populus alba × grandidentata) to divert carbon flux away from the shikimate pathway, which lies upstream of lignin biosynthesis. Transgenic poplar wood had up to 33% less lignin with p-hydroxyphenyl units comprising as much as 10% of the lignin. Mild alkaline hydrolysis of transgenic wood released fewer ester-linked p-hydroxybenzoate groups than control trees, and revealed the novel incorporation of cell-wall-bound DHB, as well as glycosides of 3,4-dihydroxybenzoic acid (DHBA). Two-dimensional nuclear magnetic resonance (2D-NMR) analysis uncovered DHBA-derived benzodioxane structures suggesting that DHB moieties were integrated into the lignin polymer backbone. In addition, up to 40% more glucose was released from transgenic wood following ionic liquid pretreatment and enzymatic hydrolysis. This work highlights the potential of diverting carbon flux from the shikimate pathway for lignin engineering and describes a new type of 'zip-lignin' derived from the incorporation of DHB into poplar lignin.
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Affiliation(s)
- Faride Unda
- Department of Wood ScienceUniversity of British Columbia2424 Main MallVancouverBCV6T 1Z4Canada
- Department of EnergyGreat Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐Madison1552 University AvenueMadisonWI53726USA
| | - Yaseen Mottiar
- Department of Wood ScienceUniversity of British Columbia2424 Main MallVancouverBCV6T 1Z4Canada
- Department of EnergyGreat Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐Madison1552 University AvenueMadisonWI53726USA
| | - Elizabeth L. Mahon
- Department of Wood ScienceUniversity of British Columbia2424 Main MallVancouverBCV6T 1Z4Canada
- Department of EnergyGreat Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐Madison1552 University AvenueMadisonWI53726USA
| | - Steven D. Karlen
- Department of EnergyGreat Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐Madison1552 University AvenueMadisonWI53726USA
- Department of BiochemistryUniversity of Wisconsin‐Madison433 Babcock DriveMadisonWI53706USA
| | - Kwang Ho Kim
- Department of Wood ScienceUniversity of British Columbia2424 Main MallVancouverBCV6T 1Z4Canada
- Clean Energy Research CenterKorea Institute of Science and TechnologySeoul02792Korea
| | - Dominique Loqué
- Joint BioEnergy Institute5885 Hollis StreetEmeryvilleCA94608USA
| | - Aymerick Eudes
- Joint BioEnergy Institute5885 Hollis StreetEmeryvilleCA94608USA
- Environmental Genomics and Systems Biology DivisionLawrence Berkeley National LaboratoryBerkeleyCA94720USA
| | - John Ralph
- Department of EnergyGreat Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐Madison1552 University AvenueMadisonWI53726USA
- Department of BiochemistryUniversity of Wisconsin‐Madison433 Babcock DriveMadisonWI53706USA
| | - Shawn D. Mansfield
- Department of Wood ScienceUniversity of British Columbia2424 Main MallVancouverBCV6T 1Z4Canada
- Department of EnergyGreat Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐Madison1552 University AvenueMadisonWI53726USA
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Mahon EL, de Vries L, Jang SK, Middar S, Kim H, Unda F, Ralph J, Mansfield SD. Exogenous chalcone synthase expression in developing poplar xylem incorporates naringenin into lignins. Plant Physiol 2022; 188:984-996. [PMID: 34718804 PMCID: PMC8825309 DOI: 10.1093/plphys/kiab499] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 09/30/2021] [Indexed: 05/03/2023]
Abstract
Lignin, a polyphenolic polymer, is a major chemical constituent of the cell walls of terrestrial plants. The biosynthesis of lignin is a highly plastic process, as highlighted by an increasing number of noncanonical monomers that have been successfully identified in an array of plants. Here, we engineered hybrid poplar (Populus alba x grandidentata) to express chalcone synthase 3 (MdCHS3) derived from apple (Malus domestica) in lignifying xylem. Transgenic trees displayed an accumulation of the flavonoid naringenin in xylem methanolic extracts not inherently observed in wild-type trees. Nuclear magnetic resonance analysis revealed the presence of naringenin in the extract-free, cellulase-treated xylem lignin of MdCHS3-poplar, indicating the incorporation of this flavonoid-derived compound into poplar secondary cell wall lignins. The transgenic trees also displayed lower total cell wall lignin content and increased cell wall carbohydrate content and performed significantly better in limited saccharification assays than their wild-type counterparts.
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Affiliation(s)
- Elizabeth L Mahon
- Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada
- US Department of Energy, Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Madison, Wisconsin, USA
| | - Lisanne de Vries
- Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada
- US Department of Energy, Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Madison, Wisconsin, USA
| | - Soo-Kyeong Jang
- Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada
| | - Sandeep Middar
- Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada
| | - Hoon Kim
- US Department of Energy, Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Madison, Wisconsin, USA
| | - Faride Unda
- Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada
- US Department of Energy, Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Madison, Wisconsin, USA
| | - John Ralph
- US Department of Energy, Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Madison, Wisconsin, USA
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin, USA
| | - Shawn D Mansfield
- Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada
- US Department of Energy, Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Madison, Wisconsin, USA
- Author for communication:
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Cullingham CI, Peery RM, Fortier CE, Mahon EL, Cooke JEK, Coltman DW. Linking genotype to phenotype to identify genetic variation relating to host susceptibility in the mountain pine beetle system. Evol Appl 2020; 13:48-61. [PMID: 31892943 PMCID: PMC6935584 DOI: 10.1111/eva.12773] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/09/2019] [Accepted: 01/13/2019] [Indexed: 12/24/2022] Open
Abstract
Identifying genetic variants responsible for phenotypic variation under selective pressure has the potential to enable productive gains in natural resource conservation and management. Despite this potential, identifying adaptive candidate loci is not trivial, and linking genotype to phenotype is a major challenge in contemporary genetics. Many of the population genetic approaches commonly used to identify adaptive candidates will simultaneously detect false positives, particularly in nonmodel species, where experimental evidence is seldom provided for putative roles of the adaptive candidates identified by outlier approaches. In this study, we use outcomes from population genetics, phenotype association, and gene expression analyses as multiple lines of evidence to validate candidate genes. Using lodgepole and jack pine as our nonmodel study species, we analyzed 17 adaptive candidate loci together with 78 putatively neutral loci at 58 locations across Canada (N > 800) to determine whether relationships could be established between these candidate loci and phenotype related to mountain pine beetle susceptibility. We identified two candidate loci that were significant across all population genetic tests, and demonstrated significant changes in transcript abundance in trees subjected to wounding or inoculation with the mountain pine beetle fungal associate Grosmannia clavigera. Both candidates are involved in central physiological processes that are likely to be invoked in a trees response to stress. One of these two candidate loci showed a significant association with mountain pine beetle attack status in lodgepole pine. The spatial distribution of the attack-associated allele further coincides with other indicators of susceptibility in lodgepole pine. These analyses, in which population genetics was combined with laboratory and field experimental validation approaches, represent first steps toward linking genetic variation to the phenotype of mountain pine beetle susceptibility in lodgepole and jack pine, and provide a roadmap for more comprehensive analyses.
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Affiliation(s)
| | - Rhiannon M. Peery
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Colleen E. Fortier
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Elizabeth L. Mahon
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
- Department of Wood ScienceUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Janice E. K. Cooke
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - David W. Coltman
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
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Mahon EL, Mansfield SD. Tailor-made trees: engineering lignin for ease of processing and tomorrow's bioeconomy. Curr Opin Biotechnol 2018; 56:147-155. [PMID: 30529238 DOI: 10.1016/j.copbio.2018.10.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 10/19/2018] [Accepted: 10/31/2018] [Indexed: 10/27/2022]
Abstract
Lignocellulosic biomass represents an abundant source of cellulosic fibres and fermentable sugars. However, lignin, a polyphenolic constituent of secondary-thickened plant cell walls significantly contributes to biomass recalcitrance during industrial processing. Efforts to reduce plant total lignin content through genetic engineering have improved processing efficiency, but often incur an agronomic penalty. Alternatively, modifications that alter the composition of lignin and/or its interaction with other cell wall polymers display improved processing efficiency without compromising biomass yield. We propose that future efforts to improve woody feedstocks should focus on altering lignin composition and cell wall ultrastructure. Here, we describe potential future modifications to lignin and/or other cell wall characteristics that may serve as strategic targets in the production of trees that are tailor-made for specific pretreatments and end-product applications.
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Affiliation(s)
- Elizabeth L Mahon
- Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Shawn D Mansfield
- Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
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