title: Hydrogen isotopic differences between C3and C4land plant lipids: consequences of compartmentation in C4photosynthetic chemistry and C3photorespiration.
abstract: The2H/1H ratio of carbon-bound H in biolipids holds potential for probing plant lipid biosynthesis and metabolism. The biochemical mechanism underlying the isotopic differences between lipids from C3and C4plants is still poorly understood. GC-pyrolysis-IRMS (gas chromatography-pyrolysis-isotope ratio mass spectrometry) measurement of the2H/1H ratio of leaf lipids from controlled and field grown plants indicates that the biochemical isotopic fractionation (ε2Hlipid_biochem) differed between C3and C4plants in a pathway-dependent manner: ε2HC4> ε2HC3for the acetogenic pathway, ε2HC4< ε2HC3for the mevalonic acid pathway and the 1-deoxy-D-xylulose 5-phosphate pathway across all species examined. It is proposed that compartmentation of photosynthetic CO2fixation into C4mesophyll (M) and bundle sheath (BS) cells and suppression of photorespiration in C4M and BS cells both result in C4M chloroplastic pyruvate - the precursor for acetogenic pathway - being more depleted in2H relative to pyruvate in C3cells. In addition, compartmentation in C4plants also results in (i) the transferable H of NADPH being enriched in2H in C4M chloroplasts compared with that in C3chloroplasts for the 1-deoxy-D-xylulose 5-phosphate pathway pathway and (ii) pyruvate relatively2H-enriched being used for the mevalonic acid pathway in the cytosol of BS cells in comparison with that in C3cells.
authors: School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China.|WA-Organic and Isotope Geochemistry Centre, The Institute for Geoscience Research, Curtin University, Perth, 6845, Australia.|Institute for Landscape Biogeochemistry, ZALF, Müncheberg, 15374, Germany.|Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China.
authors: Youping
authors: Y
authors: Zhou
authors: WA-Organic and Isotope Geochemistry Centre, The Institute for Geoscience Research, Curtin University, Perth, 6845, Australia.
authors: Kliti
authors: K
authors: Grice
authors: Research School of Biology, Australian National University, Canberra, 2601, Australia.
authors: Hilary
authors: H
authors: Stuart-Williams
authors: Research School of Biology, Australian National University, Canberra, 2601, Australia.
authors: Charles H
authors: CH
authors: Hocart
authors: Institute for Landscape Biogeochemistry, ZALF, Müncheberg, 15374, Germany.|Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, 8903, Switzerland.
authors: Arthur
authors: A
authors: Gessler
authors: Research School of Biology, Australian National University, Canberra, 2601, Australia.
authors: Graham D
authors: GD
authors: Farquhar
mesh_terms: D019069:Cell Respiration; D002849:Chromatography, Gas; D003903:Deuterium / Q000378:metabolism*; D019669:Embryophyta / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D050356:Lipid Metabolism / Q000502:physiology; D053858:Metabolic Networks and Pathways; D010788:Photosynthesis
chemical_list: D006859:Hydrogen; D003903:Deuterium
keywords: C3 photorespiration; C4 compartmentation; isotope effect; lipid biosynthesis; natural abundance hydrogen isotope composition