title: Mesophyll conductance to CO2 in Arabidopsis thaliana.
abstract: The close rosette growth form, short petioles and small leaves of Arabidopsis thaliana make measurements with commercial gas exchange cuvettes difficult. This difficulty can be overcome by growing A. thaliana plants in 'ice-cream cone-like' soil pots. This design permitted simultaneous gas exchange and chlorophyll fluorescence measurements from which the first estimates of mesophyll conductance to CO(2) (g(m)) in Arabidopsis were obtained and used to determine photosynthetic limitations during plant ageing from c. 30-45 d. Estimations of g(m) showed maximum values of 0.2 mol CO(2) m(-2) s(-1) bar(-1), lower than expected for a thin-leaved annual species. The parameterization of the response of net photosynthesis (A(N)) to chloroplast CO(2) concentrations (C(c)) yielded estimations of the maximum velocity of carboxylation (V(c,max_Cc)) which were also lower than those reported for other annual species. As A. thaliana plants aged from 30 to 45 d, there was a 40% decline of A(N) that was entirely the result of increased diffusional limitations to CO(2) transfer, with g(m) being the largest. The results suggest that in A. thaliana A(N) is limited by low g(m) and low capacity for carboxylation. Decreased g(m) is the main factor involved in early age-induced photosynthetic decline.
authors.affiliation: Laboratori de Fisiologia Vegetal, Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Flexas
authors.affiliation: Departamento Botânica e Engenharia Biológica, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: M F
authors.initials: MF
authors.lastname: Ortuño
authors.affiliation: Laboratori de Fisiologia Vegetal, Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Ribas-Carbo
authors.affiliation: Instituto de Recursos Naturales y Agrobiología, CSIC, Apartado 1052, 41080 Sevilla, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Diaz-Espejo
authors.affiliation: Laboratori de Fisiologia Vegetal, Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
authors.forename: I D
authors.initials: ID
authors.lastname: Flórez-Sarasa
authors.affiliation: Laboratori de Fisiologia Vegetal, Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
authors.forename: H
authors.initials: H
authors.lastname: Medrano
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D005453:Fluorescence; D010788:Photosynthesis; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism
chemical_list: D002734:Chlorophyll; D002245:Carbon Dioxide