title: Photosynthetic characterization of Rubisco transplantomic lines reveals alterations on photochemistry and mesophyll conductance.
abstract: Improving Rubisco catalysis is considered a promising way to enhance C3-photosynthesis and photosynthetic water use efficiency (WUE) provided the introduced changes have little or no impact on other processes affecting photosynthesis such as leaf photochemistry or leaf CO2 diffusion conductances. However, the extent to which the factors affecting photosynthetic capacity are co-regulated is unclear. The aim of the present study was to characterize the photochemistry and CO2 transport processes in the leaves of three transplantomic tobacco genotypes expressing hybrid Rubisco isoforms comprising different Flaveria L-subunits that show variations in catalysis and differing trade-offs between the amount of Rubisco and its activation state. Stomatal conductance (g s) in each transplantomic tobacco line matched wild-type, while their photochemistry showed co-regulation with the variations in Rubisco catalysis. A tight co-regulation was observed between Rubisco activity and mesophyll conductance (g m) that was independent of g s thus producing plants with varying g m/g s ratios. Since the g m/g s ratio has been shown to positively correlate with intrinsic WUE, the present results suggest that altering photosynthesis by modifying Rubisco catalysis may also be useful for targeting WUE.
authors.affiliation: Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Ctra. de Valldemossa Km.7.5, 07122 Palma, Spain. jeroni.galmes@uib.cat
authors.forename: Jeroni
authors.initials: J
authors.lastname: Galmés
authors.forename: Juan Alejandro
authors.initials: JA
authors.lastname: Perdomo
authors.forename: Jaume
authors.initials: J
authors.lastname: Flexas
authors.forename: Spencer M
authors.initials: SM
authors.lastname: Whitney
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D002384:Catalysis; D002734:Chlorophyll / Q000032:analysis / Q000378:metabolism; D000077194:Chlorophyll A; D004789:Enzyme Activation; D037142:Flaveria / Q000235:genetics / Q000378:metabolism*; D058503:Mesophyll Cells / Q000378:metabolism; D010777:Photochemistry / Q000379:methods; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000502:physiology; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D054046:Plant Stomata / Q000502:physiology; D030821:Plants, Genetically Modified; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D014867:Water; D002734:Chlorophyll; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase; D000077194:Chlorophyll A