title: Does ear C sink strength contribute to overcoming photosynthetic acclimation of wheat plants exposed to elevated CO2?
abstract: Wheat plants (Triticum durum Desf., cv. Regallo) were grown in the field to study the effects of contrasting [CO(2)] conditions (700 versus 370 μmol mol(-1)) on growth, photosynthetic performance, and C management during the post-anthesis period. The aim was to test whether a restricted capacity of sink organs to utilize photosynthates drives a loss of photosynthetic capacity in elevated CO(2). The ambient (13)C/(12)C isotopic composition (δ(13)C) of air CO(2) was changed from -10.2‰ in ambient [CO(2)] to -23.6‰ under elevated [CO(2)] between the 7th and the 14th days after anthesis in order to study C assimilation and partitioning between leaves and ears. Elevated [CO(2)] had no significant effect on biomass production and grain filling, and caused an accumulation of C compounds in leaves. This was accompanied by up-regulation of phosphoglycerate mutase and ATP synthase protein content, together with down-regulation of adenosine diphosphate glucose pyrophosphatase protein. Growth in elevated [CO(2)] negatively affected Rubisco and Rubisco activase protein content and induced photosynthetic down-regulation. CO(2) enrichment caused a specific decrease in Rubisco content, together with decreases in the amino acid and total N content of leaves. The C labelling revealed that in flag leaves, part of the C fixed during grain filling was stored as starch and structural C compounds whereas the rest of the labelled C (mainly in the form of soluble sugars) was completely respired 48 h after the end of labelling. Although labelled C was not detected in the δ(13)C of ear total organic matter and respired CO(2), soluble sugar δ(13)C revealed that a small amount of labelled C reached the ear. The (12)CO(2) labelling suggests that during the beginning of post-anthesis the ear did not contribute towards overcoming flag leaf carbohydrate accumulation, and this had a consequent effect on protein expression and photosynthetic acclimation.
authors.affiliation: Universidad Pública de Navarra-CSIC-Gobierno de Navarra, Campus de Arrosadia, Mutilva Baja, Spain. iker.aranjuelo@gmail.com
authors.forename: Iker
authors.initials: I
authors.lastname: Aranjuelo
authors.forename: Llorenç
authors.initials: L
authors.lastname: Cabrera-Bosquet
authors.forename: Rosa
authors.initials: R
authors.lastname: Morcuende
authors.forename: Jean Christophe
authors.initials: JC
authors.lastname: Avice
authors.forename: Salvador
authors.initials: S
authors.lastname: Nogués
authors.forename: José Luis
authors.initials: JL
authors.lastname: Araus
authors.forename: Rafael
authors.initials: R
authors.lastname: Martínez-Carrasco
authors.forename: Pilar
authors.initials: P
authors.lastname: Pérez
mesh_terms: D000064:Acclimatization; D000596:Amino Acids / Q000378:metabolism; D018533:Biomass; D002244:Carbon / Q000032:analysis* / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis* / Q000378:metabolism; D019069:Cell Respiration; D002523:Edible Grain / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010736:Phosphoglycerate Mutase / Q000378:metabolism; D010788:Photosynthesis; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D014908:Triticum / Q000254:growth & development / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D010940:Plant Proteins; C054765:rca protein, plant; D002245:Carbon Dioxide; D002244:Carbon; D013213:Starch; D025261:Mitochondrial Proton-Translocating ATPases; D012273:Ribulose-Bisphosphate Carboxylase; D010736:Phosphoglycerate Mutase; D009584:Nitrogen