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Sun X, Cheng L, Jonker A, Munidasa S, Pacheco D. A Review: Plant Carbohydrate Types—The Potential Impact on Ruminant Methane Emissions. Front Vet Sci 2022; 9:880115. [PMID: 35782553 PMCID: PMC9249355 DOI: 10.3389/fvets.2022.880115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/16/2022] [Indexed: 11/25/2022] Open
Abstract
Carbohydrates are the major component of most ruminant feeds. The digestion of carbohydrates in the rumen provides energy to the ruminants but also contributes to enteric methane (CH4) emissions. Fresh forage is the main feed for grazing ruminants in temperate regions. Therefore, this review explored how dietary carbohydrate type and digestion affect ruminant CH4 emissions, with a focus on fresh forage grown in temperate regions. Carbohydrates include monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Rhamnose is the only monosaccharide that results in low CH4 emissions. However, rhamnose is a minor component in most plants. Among polysaccharides, pectic polysaccharides lead to greater CH4 production due to the conversion of methyl groups to methanol and finally to CH4. Thus, the degree of methyl esterification of pectic polysaccharides is an important structural characteristic to better understand CH4 emissions. Apart from pectic polysaccharides, the chemical structure of other polysaccharides per se does not seem to affect CH4 formation. However, rumen physiological parameters and fermentation types resulting from digestion in the rumen of polysaccharides differing in the rate and extent of degradation do affect CH4 emissions. For example, low rumen pH resulting from the rapid degradation of readily fermentable carbohydrates decreases and inhibits the activities of methanogens and further reduces CH4 emissions. When a large quantity of starch is supplemented or the rate of starch degradation is low, some starch may escape from the rumen and the escaped starch will not yield CH4. Similar bypass from rumen digestion applies to other polysaccharides and needs to be quantified to facilitate the interpretation of animal experiments in which CH4 emissions are measured. Rumen bypass carbohydrates may occur in ruminants fed fresh forage, especially when the passage rate is high, which could be a result of high feed intake or high water intake. The type of carbohydrates affects the concentration of dissolved hydrogen, which consequently alters fermentation pathways and finally results in differences in CH4 emissions. We recommend that the degree of methyl esterification of pectic polysaccharides is needed for pectin-rich forage. The fermentation type of carbohydrates and rumen bypass carbohydrates should be determined in the assessment of mitigation potential.
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Affiliation(s)
- Xuezhao Sun
- The Innovation Centre of Ruminant Precision Nutrition and Smart and Ecological Farming, Jilin Agricultural Science and Technology University, Jilin, China
- Jilin Inter-Regional Cooperation Centre for the Scientific and Technological Innovation of Ruminant Precision Nutrition and Smart and Ecological Farming, Jilin, China
- Grasslands Research Centre, AgResearch Limited, Palmerston North, New Zealand
- *Correspondence: Xuezhao Sun
| | - Long Cheng
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Arjan Jonker
- Grasslands Research Centre, AgResearch Limited, Palmerston North, New Zealand
| | - Sineka Munidasa
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC, Australia
| | - David Pacheco
- Grasslands Research Centre, AgResearch Limited, Palmerston North, New Zealand
- David Pacheco
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Kanungo A, Bag BP. Structural insights into the molecular mechanisms of pectinolytic enzymes. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s42485-019-00027-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Urbanowicz BR, Bharadwaj VS, Alahuhta M, Peña MJ, Lunin VV, Bomble YJ, Wang S, Yang JY, Tuomivaara ST, Himmel ME, Moremen KW, York WS, Crowley MF. Structural, mutagenic and in silico studies of xyloglucan fucosylation in Arabidopsis thaliana suggest a water-mediated mechanism. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 91:931-949. [PMID: 28670741 PMCID: PMC5735850 DOI: 10.1111/tpj.13628] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 06/21/2017] [Accepted: 06/22/2017] [Indexed: 05/17/2023]
Abstract
The mechanistic underpinnings of the complex process of plant polysaccharide biosynthesis are poorly understood, largely because of the resistance of glycosyltransferase (GT) enzymes to structural characterization. In Arabidopsis thaliana, a glycosyl transferase family 37 (GT37) fucosyltransferase 1 (AtFUT1) catalyzes the regiospecific transfer of terminal 1,2-fucosyl residues to xyloglucan side chains - a key step in the biosynthesis of fucosylated sidechains of galactoxyloglucan. We unravel the mechanistic basis for fucosylation by AtFUT1 with a multipronged approach involving protein expression, X-ray crystallography, mutagenesis experiments and molecular simulations. Mammalian cell culture expressions enable the sufficient production of the enzyme for X-ray crystallography, which reveals the structural architecture of AtFUT1 in complex with bound donor and acceptor substrate analogs. The lack of an appropriately positioned active site residue as a catalytic base leads us to propose an atypical water-mediated fucosylation mechanism facilitated by an H-bonded network, which is corroborated by mutagenesis experiments as well as detailed atomistic simulations.
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Affiliation(s)
- Breeanna R. Urbanowicz
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Vivek S. Bharadwaj
- Biosciences Division, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Markus Alahuhta
- Biosciences Division, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Maria J. Peña
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Vladimir V. Lunin
- Biosciences Division, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Yannick J. Bomble
- Biosciences Division, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Shuo Wang
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Jeong-Yeh Yang
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Sami T. Tuomivaara
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Michael E. Himmel
- Biosciences Division, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Kelley W. Moremen
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - William S. York
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Michael F. Crowley
- Biosciences Division, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
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Onoda Y, Wright IJ, Evans JR, Hikosaka K, Kitajima K, Niinemets Ü, Poorter H, Tosens T, Westoby M. Physiological and structural tradeoffs underlying the leaf economics spectrum. THE NEW PHYTOLOGIST 2017; 214:1447-1463. [PMID: 28295374 DOI: 10.1111/nph.14496] [Citation(s) in RCA: 250] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/23/2017] [Indexed: 05/18/2023]
Abstract
The leaf economics spectrum (LES) represents a suite of intercorrelated leaf traits concerning construction costs per unit leaf area, nutrient concentrations, and rates of carbon fixation and tissue turnover. Although broad trade-offs among leaf structural and physiological traits have been demonstrated, we still do not have a comprehensive view of the fundamental constraints underlying the LES trade-offs. Here, we investigated physiological and structural mechanisms underpinning the LES by analysing a novel data compilation incorporating rarely considered traits such as the dry mass fraction in cell walls, nitrogen allocation, mesophyll CO2 diffusion and associated anatomical traits for hundreds of species covering major growth forms. The analysis demonstrates that cell wall constituents are major components of leaf dry mass (18-70%), especially in leaves with high leaf mass per unit area (LMA) and long lifespan. A greater fraction of leaf mass in cell walls is typically associated with a lower fraction of leaf nitrogen (N) invested in photosynthetic proteins; and lower within-leaf CO2 diffusion rates, as a result of thicker mesophyll cell walls. The costs associated with greater investments in cell walls underpin the LES: long leaf lifespans are achieved via higher LMA and in turn by higher cell wall mass fraction, but this inevitably reduces the efficiency of photosynthesis.
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Affiliation(s)
- Yusuke Onoda
- Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan
| | - Ian J Wright
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - John R Evans
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia
| | - Kouki Hikosaka
- Graduate School of Life Sciences, Tohoku University, Aoba, Sendai, 980-8578, Japan
| | - Kaoru Kitajima
- Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan
| | - Ülo Niinemets
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, 51014, Estonia
| | - Hendrik Poorter
- Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
| | - Tiina Tosens
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, 51014, Estonia
| | - Mark Westoby
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
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Kumar M, Campbell L, Turner S. Secondary cell walls: biosynthesis and manipulation. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:515-31. [PMID: 26663392 DOI: 10.1093/jxb/erv533] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Secondary cell walls (SCWs) are produced by specialized plant cell types, and are particularly important in those cells providing mechanical support or involved in water transport. As the main constituent of plant biomass, secondary cell walls are central to attempts to generate second-generation biofuels. Partly as a consequence of this renewed economic importance, excellent progress has been made in understanding how cell wall components are synthesized. SCWs are largely composed of three main polymers: cellulose, hemicellulose, and lignin. In this review, we will attempt to highlight the most recent progress in understanding the biosynthetic pathways for secondary cell wall components, how these pathways are regulated, and how this knowledge may be exploited to improve cell wall properties that facilitate breakdown without compromising plant growth and productivity. While knowledge of individual components in the pathway has improved dramatically, how they function together to make the final polymers and how these individual polymers are incorporated into the wall remain less well understood.
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Affiliation(s)
- Manoj Kumar
- University of Manchester, The Micheal Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Liam Campbell
- University of Manchester, The Micheal Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Simon Turner
- University of Manchester, The Micheal Smith Building, Oxford Road, Manchester M13 9PT, UK
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