title: Dynamic balancing of isoprene carbon sources reflects photosynthetic and photorespiratory responses to temperature stress.
abstract: The volatile gas isoprene is emitted in teragrams per annum quantities from the terrestrial biosphere and exerts a large effect on atmospheric chemistry. Isoprene is made primarily from recently fixed photosynthate; however, alternate carbon sources play an important role, particularly when photosynthate is limiting. We examined the relative contribution of these alternate carbon sources under changes in light and temperature, the two environmental conditions that have the strongest influence over isoprene emission. Using a novel real-time analytical approach that allowed us to examine dynamic changes in carbon sources, we observed that relative contributions do not change as a function of light intensity. We found that the classical uncoupling of isoprene emission from net photosynthesis at elevated leaf temperatures is associated with an increased contribution of alternate carbon. We also observed a rapid compensatory response where alternate carbon sources compensated for transient decreases in recently fixed carbon during thermal ramping, thereby maintaining overall increases in isoprene production rates at high temperatures. Photorespiration is known to contribute to the decline in net photosynthesis at high leaf temperatures. A reduction in the temperature at which the contribution of alternate carbon sources increased was observed under photorespiratory conditions, while photosynthetic conditions increased this temperature. Feeding [2-(13)C]glycine (a photorespiratory intermediate) stimulated emissions of [(13)C1-5]isoprene and (13)CO2, supporting the possibility that photorespiration can provide an alternate source of carbon for isoprene synthesis. Our observations have important implications for establishing improved mechanistic predictions of isoprene emissions and primary carbon metabolism, particularly under the predicted increases in future global temperatures.
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.) kjjardine@lbl.gov.
authors.forename: Kolby
authors.identifier: http://orcid.org/0000-0001-8491-9310
authors.initials: K
authors.lastname: Jardine
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Chambers
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Eliane G
authors.initials: EG
authors.lastname: Alves
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Andrea
authors.initials: A
authors.lastname: Teixeira
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Sabrina
authors.initials: S
authors.lastname: Garcia
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Jennifer
authors.initials: J
authors.lastname: Holm
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Niro
authors.initials: N
authors.lastname: Higuchi
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Antonio
authors.initials: A
authors.lastname: Manzi
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Leif
authors.initials: L
authors.lastname: Abrell
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Jose D
authors.initials: JD
authors.lastname: Fuentes
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Lars K
authors.initials: LK
authors.lastname: Nielsen
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Margaret S
authors.initials: MS
authors.lastname: Torn
authors.affiliation: Climate Science Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (K.J., J.C., J.H., M.S.T.);National Institute for Amazon Research, Manaus, Amazonas 69080-971, Brazil (E.G.A., A.T., S.G., N.H., A.M.);Departments of Chemistry and Biochemistry and Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721 (L.A.);Department of Meteorology, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (J.D.F.); andAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, St. Lucia, Queensland 4072, Australia (L.K.N., C.E.V.).
authors.forename: Claudia E
authors.initials: CE
authors.lastname: Vickers
mesh_terms: D002070:Butadienes / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes / Q000032:analysis; D004777:Environment; D045782:Hemiterpenes / Q000378:metabolism*; D006358:Hot Temperature; D008027:Light; D010420:Pentanes / Q000378:metabolism*; D010788:Photosynthesis; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D013696:Temperature; D013729:Terpenes / Q000378:metabolism*; D014197:Trees / Q000502:physiology* / Q000528:radiation effects
chemical_list: D002070:Butadienes; D002247:Carbon Isotopes; D045782:Hemiterpenes; D010420:Pentanes; D013729:Terpenes; C005059:isoprene; D002245:Carbon Dioxide; D002244:Carbon