title: Mesophyll conductance and reaction-diffusion models for CO2transport in C3leaves; needs, opportunities and challenges.
abstract: One way to increase potential crop yield could be increasing mesophyll conductance gm. This variable determines the difference between the CO2partial pressure in the intercellular air spaces (Ci) and that near Rubisco (Cc). Various methods can determine gmfrom gas exchange measurements, often combined with measurements of chlorophyll fluorescence or carbon isotope discrimination. gmlumps all biochemical and physical factors that cause the difference between Ccand Ci. gmappears to vary with Ci. This variability indicates that gmdoes not satisfy the physical definition of a conductance according to Fick's first law and is thus an apparent parameter. Uncertainty about the mechanisms that determine gmcan be limited to some extent by using analytical models that partition gminto separate conductances. Such models are still only capable of describing the CO2diffusion pathway to a limited extent, as they make implicit assumptions about the position of mitochondria in the cells, which affect the re-assimilation of (photo)respired CO2. Alternatively, reaction-diffusion models may be used. Rather than quantifying gm, these models explicitly account for factors that affect the efficiency of CO2transport in the mesophyll. These models provide a better mechanistic description of the CO2diffusion pathways than mesophyll conductance models. Therefore, we argue that reaction-diffusion models should be used as an alternative to mesophyll conductance models, in case the aim of such a study is to identify traits that can be improved to increase gm.
authors.affiliation: Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium. Electronic address: herman.berghuijs@wur.nl.
authors.forename: Herman N C
authors.initials: HN
authors.lastname: Berghuijs
authors.affiliation: Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
authors.forename: Xinyou
authors.initials: X
authors.lastname: Yin
authors.affiliation: Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium.
authors.forename: Q Tri
authors.initials: QT
authors.lastname: Ho
authors.affiliation: Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Driever
authors.affiliation: Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium.
authors.forename: Moges A
authors.initials: MA
authors.lastname: Retta
authors.affiliation: Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium.
authors.forename: Bart M
authors.initials: BM
authors.lastname: Nicolaï
authors.affiliation: Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Struik
mesh_terms: D001692:Biological Transport; D002245:Carbon Dioxide / Q000378:metabolism*; D004058:Diffusion; D058503:Mesophyll Cells / Q000502:physiology*; D008962:Models, Theoretical; D010313:Partial Pressure; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism; D018521:Plant Physiological Phenomena; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism
chemical_list: D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase
keywords: 3D models; C(3) plants; CO(2); Mesophyll conductance; Photosynthesis; Reaction-diffusion models