title: Size matters for single-cell C4 photosynthesis in Bienertia.
abstract: Bienertia cycloptera belongs to a diverse set of plants, recently discovered to perform C4photosynthesis within individual mesophyll cells. How these plants accomplish high photosynthetic efficiency without adopting Kranz anatomy remains unanswered. By modelling the processes of diffusion, capture, and release of carbon dioxide and oxygen inside a typical Bienertia mesophyll cell geometry, we show that a spatial separation as low as 10 μm between the primary and the secondary carboxylases, can, on its own, provide enough diffusive resistance to sustain a viable C4pathway at 20 °C, with a CO2leakage <35%. This critical separation corresponds to a cell diameter of 50 μm, consistent with the observed range where Bienertia's mesophyll cells start to develop their characteristic mature anatomy. Our results are robust to significant alterations in model assumptions and environmental conditions, their applicability extending even to aquatic plants.
authors.affiliation: Warwick Systems Biology Centre, University of Warwick, Coventry CV4 7AL, UK i.juric@warwick.ac.uk n.j.burroughs@warwick.ac.uk.|Institute of Physics, Bijenička c. 46, PO Box 304, HR-10001 Zagreb, Croatia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Jurić
authors.affiliation: Warwick Systems Biology Centre, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Vinicio
authors.initials: V
authors.lastname: González-Pérez
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK.
authors.forename: Julian M
authors.initials: JM
authors.lastname: Hibberd
authors.affiliation: School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA.
authors.forename: Gerald
authors.initials: G
authors.lastname: Edwards
authors.affiliation: Warwick Systems Biology Centre, University of Warwick, Coventry CV4 7AL, UK i.juric@warwick.ac.uk n.j.burroughs@warwick.ac.uk.
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Burroughs
mesh_terms: D019663:Chenopodiaceae / Q000166:cytology / Q000378:metabolism*; D058503:Mesophyll Cells / Q000378:metabolism*; D008954:Models, Biological; D008956:Models, Chemical; D010788:Photosynthesis
keywords: Bienertia; C4 photosynthesis; carbon fixation; photon cost; photosynthetic efficiency; single-cell C4
  ; spatial modelling.