title: Increase of photosynthesis and starch in potato under elevated CO2 is dependent on leaf age.
abstract: Potato plants (Solanum tuberosum cv. Bintje) were grown in open top chambers under ambient (400 microL L(-1)) and elevated CO2 (720 microL L(-1)). After 50 days one half of each group was transferred to the other CO2 concentration and the effects were studied in relation to leaf age (old, middle-aged and young leaves) in each of the four groups. Under long-term exposure to elevated CO2, photosynthesis increased between 10% and 40% compared to ambient CO2. A subsequent shift of the same plants to ambient CO2 caused a 20-40% decline in photosynthetic rate, which was most pronounced in young leaves. After shifting from long-term ambient to elevated CO2, photosynthesis also increased most strongly in young leaves (90%); these experiments show that photosynthesis was downregulated in the upper young fully expanded leaves of potato growing long-term under elevated CO2. Soluble sugar content in all leaf classes under long-term exposure was stable irrespective of the CO2 treatment, however under elevated CO2 young leaves showed a strongly increased starch accumulation (up to 400%). In all leaf classes starch levels dropped in response to the shift from 720 to 400 microL L(-1) approaching ambient CO2 levels. After the shift to 720 microL L(-1), sucrose and starch levels increased, principally in young Leaves. There is clear evidence that leaves of different age vary in their responses to changes in atmospheric CO2 concentration.
authors.affiliation: Institute of General Botany, Justus Liebig University, Senckenbergstrasse 17, 35390 Giessen, Germany. angecasanova@udec.cl
authors.forename: María Angélica Casanova
authors.initials: MA
authors.lastname: Katny
authors.forename: Gudrun
authors.initials: G
authors.lastname: Hoffmann-Thoma
authors.forename: Anton Arij
authors.initials: AA
authors.lastname: Schrier
authors.forename: Andreas
authors.initials: A
authors.lastname: Fangmeier
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Jäger
authors.forename: Aart J E
authors.initials: AJ
authors.lastname: van Bel
mesh_terms: D002245:Carbon Dioxide / Q000502:physiology*; D002940:Circadian Rhythm; D005632:Fructose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology*; D011198:Solanum tuberosum / Q000378:metabolism / Q000502:physiology*; D013213:Starch / Q000096:biosynthesis*; D013395:Sucrose / Q000378:metabolism; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D005632:Fructose; D013395:Sucrose; D013213:Starch; D005947:Glucose