title: Foliar CO2 fixation in bean (Phaseolus vulgaris L.) submitted to elevated ozone: distinct changes in Rubisco and PEPc activities in relation to pigment content.
abstract: Using open-top chambers, the impact of ozone (O(3)) on foliar carboxylases of bean (Phaseolus vulgaris L.) was investigated. From sowing, beans were exposed to non-filtered air (NF) and NF supplied with 40 (+40) and 80 (+80) nL L(-1) O(3). Twenty days after emergence, primary and first trifoliate leaves were sampled. Biochemical characteristics of leaves from +40 were quite similar to those from NF. Conversely, +80 induced distinct biochemical effects in primary and first trifoliate leaves. Regarding primary leaves, +80 reduced ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity by 33% whereas it stimulated phosphoenolpyruvate carboxylase (PEPc) activity by 376%. The reduction in Rubisco activity was accompanied by a decrease in both Rubisco subunit amounts and a consistent oxidative modification of the Rubisco small subunit (SSU). These changes came with a drastic loss in pigmentation. Regarding first trifoliate leaves, +80 stimulated Rubisco activity by 33% while it disturbed neither PEPc activity nor pigmentation. Surprisingly, the enhanced Rubisco activity was associated with a slight decrease in Rubisco protein quantity, which was not coupled with the formation of carbonyl groups in Rubisco-SSU.
authors.affiliation: Laboratoire d'Ecologie Moléculaire, EA 3525, IBEAS, Université de Pau et des Pays de l'Adour, Pau Cedex, France.
authors.forename: Louis
authors.initials: L
authors.lastname: Leitao
authors.forename: Pierre
authors.initials: P
authors.lastname: Dizengremel
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Biolley
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010126:Ozone / Q000494:pharmacology*; D027805:Phaseolus / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D010730:Phosphoenolpyruvate Carboxylase / Q000187:drug effects / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000187:drug effects / Q000378:metabolism*; D012621:Seasons
chemical_list: D002245:Carbon Dioxide; D010126:Ozone; D010730:Phosphoenolpyruvate Carboxylase; D012273:Ribulose-Bisphosphate Carboxylase; D010100:Oxygen