title: Interaction of drought and elevated CO2 concentration on photosynthetic down-regulation and susceptibility to photoinhibition in Japanese white birch seedlings grown with limited N availability.
abstract: The interaction of drought and elevated carbon dioxide concentration ([CO(2)]) on carboxylation capacity of Rubisco (V(cmax)) and susceptibility to photoinhibition may be an important determinant of plant responses to seasonal fluctuations in precipitation in an anticipated elevated [CO(2)] environment. Japanese white birch (Betula platyphylla var. japonica) leaves that developed wholly during a period of drought showed an increase in leaf nitrogen and a decrease in leaf carbohydrates that could ameliorate photosynthetic down-regulation, defined as a decrease in V(cmax) in response to elevated [CO(2)]. Photochemical quenching (q(P)) was decreased by elevated [CO(2)] but increased by drought when compared at a given intercellular [CO(2)] (C(i)), indicating that elevated [CO(2)] could increase the risk of photoinhibition, whereas long-term drought could alleviate the risk of photoinhibition. However, only a small variation in q(P) was measured among seedlings in the various water availability x [CO(2)] treatment combinations, consistent with the small treatment differences in chronic photoinhibition among the seedlings, as indicated by the ratio of variable to maximum chlorophyll fluorescence after overnight dark-adaptation. Our results suggest that the offsetting responses-reduced V(cmax) plus increased C(i) at elevated [CO(2)] and increased V(cmax) plus reduced C(i) under drought conditions-resulted in a narrow range of susceptibility to photoinhibition at the growth [CO(2)] in Japanese white birch seedlings grown in various water availability x [CO(2)] treatment combinations.
authors.affiliation: Hokkaido Research Center, Forestry and Forest Products Research Institute, Sapporo 062-8516, Japan. kitao@ffpri.affrc.go.jp
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Kitao
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Lei
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Koike
authors.forename: Masazumi
authors.initials: M
authors.lastname: Kayama
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tobita
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Maruyama
mesh_terms: D029662:Betula / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D050260:Carbohydrate Metabolism; D002245:Carbon Dioxide / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism / Q000502:physiology; D010788:Photosynthesis / Q000502:physiology* / Q000528:radiation effects; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D036226:Seedlings / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D014867:Water / Q000502:physiology*
chemical_list: D014867:Water; D002734:Chlorophyll; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen