title: Temperature responses of Rubisco from Paniceae grasses provide opportunities for improving C3photosynthesis.
abstract: Enhancing the catalytic properties of the CO2-fixing enzyme Rubisco is a target for improving agricultural crop productivity. Here, we reveal extensive diversity in the kinetic response between 10 and 37 °C by Rubisco from C3and C4species within the grass tribe Paniceae. The CO2fixation rate (kcatc) for Rubisco from the C4grasses with nicotinamide adenine dinucleotide (NAD) phosphate malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PCK) photosynthetic pathways was twofold greater than the kcatc of Rubisco from NAD-ME species across all temperatures. The declining response of CO2/O2specificity with increasing temperature was less pronounced for PCK and NADP-ME Rubisco, which would be advantageous in warmer climates relative to the NAD-ME grasses. Modelled variation in the temperature kinetics of Paniceae C3Rubisco and PCK Rubisco differentially stimulated C3photosynthesis relative to tobacco above and below 25 °C under current and elevated CO2. Amino acid substitutions in the large subunit that could account for the catalytic variation among Paniceae Rubisco are identified; however, incompatibilities with Paniceae Rubisco biogenesis in tobacco hindered their mutagenic testing by chloroplast transformation. Circumventing these bioengineering limitations is critical to tailoring the properties of crop Rubisco to suit future climates.
authors.affiliation: Research School of Biology, Australian National University, Canberra Australian Capital Territory 2601, Australia.|ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra Australian Capital Territory 2601, Australia.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Sharwood
authors.affiliation: ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra Australian Capital Territory 2601, Australia.|Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2753, Australia.
authors.forename: Oula
authors.initials: O
authors.lastname: Ghannoum
authors.affiliation: School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 3AF, UK.
authors.forename: Maxim V
authors.identifier: 0000-0001-7966-0295
authors.initials: MV
authors.lastname: Kapralov
authors.affiliation: Research School of Biology, Australian National University, Canberra Australian Capital Territory 2601, Australia.
authors.forename: Laura H
authors.initials: LH
authors.lastname: Gunn
authors.affiliation: Research School of Biology, Australian National University, Canberra Australian Capital Territory 2601, Australia.|ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra Australian Capital Territory 2601, Australia.
authors.forename: Spencer M
authors.initials: SM
authors.lastname: Whitney
mesh_terms: D002244:Carbon / Q000737:chemistry / Q000378:metabolism*; D008957:Models, Genetic; D010788:Photosynthesis; D006109:Poaceae / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism*
chemical_list: D002244:Carbon; D012273:Ribulose-Bisphosphate Carboxylase