title: Deficiency of mitochondrial fumarase activity in tomato plants impairs photosynthesis via an effect on stomatal function.
abstract: Transgenic tomato (Solanum lycopersicum) plants expressing a fragment of a fumarate hydratase (fumarase) gene in the antisense orientation and exhibiting considerable reductions in the mitochondrial activity of this enzyme show impaired photosynthesis. The rate of the tricarboxylic acid cycle was reduced in the transformants relative to the other major pathways of carbohydrate oxidation and the plants were characterized by a restricted rate of dark respiration. However, biochemical analyses revealed relatively little alteration in leaf metabolism as a consequence of reducing the fumarase activity. That said, in comparison to wild-type plants, CO(2) assimilation was reduced by up to 50% under atmospheric conditions and plants were characterized by a reduced biomass on a whole plant basis. Analysis of further photosynthetic parameters revealed that there was little difference in pigment content in the transformants but that the rate of transpiration and stomatal conductance was markedly reduced. Analysis of the response of the rate of photosynthesis to variation in the concentration of CO(2) confirmed that this restriction was due to a deficiency in stomatal function.
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Golm, Germany.
authors.forename: Adriano
authors.initials: A
authors.lastname: Nunes-Nesi
authors.forename: Fernando
authors.initials: F
authors.lastname: Carrari
authors.forename: Yves
authors.initials: Y
authors.lastname: Gibon
authors.forename: Ronan
authors.initials: R
authors.lastname: Sulpice
authors.forename: Anna
authors.initials: A
authors.lastname: Lytovchenko
authors.forename: Joachim
authors.initials: J
authors.lastname: Fisahn
authors.forename: James
authors.initials: J
authors.lastname: Graham
authors.forename: R George
authors.initials: RG
authors.lastname: Ratcliffe
authors.forename: Lee J
authors.initials: LJ
authors.lastname: Sweetlove
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D002952:Citric Acid Cycle / Q000502:physiology; D018076:DNA, Complementary; D004579:Electron Transport / Q000502:physiology; D005638:Fruit / Q000254:growth & development; D005649:Fumarate Hydratase / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000502:physiology; D008293:Malates / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology*; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology*; D018517:Plant Roots / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000254:growth & development / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D008293:Malates; D002244:Carbon; C030298:malic acid; D005649:Fumarate Hydratase