title: Photosynthetic capacity and light harvesting efficiency during the winter-to-spring transition in subalpine conifers.
abstract: Some coniferous forest ecosystems undergo complete photosynthetic down-regulation in winter. The present study examined the influence of several environmental parameters on intrinsic, needle-level photosynthesis and photoprotection during the spring reactivation of photosynthesis in subalpine conifers. Maximal photosystem II (PSII) efficiency, photosynthetic capacity, and amounts of zeaxanthin and early light-inducible protein (Elip) family members were assessed in three subalpine conifer species over 3 years, and intensively during the 2003 winter-to-spring transition. During summers, maximal PSII efficiency remained high while intrinsic photosynthetic capacity varied depending on precipitation. During winters and the winter-to-spring transition, photosynthetic capacity and PSII efficiency were highly correlated and (during the spring transition) strongly influenced by air and soil temperature and liquid water availability. Decreases in the amount of Elip family members from winter through spring paralleled disengagement of sustained zeaxanthin-dependent photoprotection, although one of four anti-Elip antibody-reactive bands increased during spring. Intrinsic photosynthetic capacity and maximal PSII efficiency were highly responsive to day-to-day environmental changes during spring, indicating that multiple environmental signals are integrated to orchestrate the reactivation of photosynthesis from the inactive winter state to the active summer state.
authors.affiliation: Department of Ecology & Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA.
authors.forename: C Ryan
authors.initials: CR
authors.lastname: Zarter
authors.forename: Barbara
authors.initials: B
authors.lastname: Demmig-Adams
authors.forename: Volker
authors.initials: V
authors.lastname: Ebbert
authors.forename: Iwona
authors.initials: I
authors.lastname: Adamska
authors.forename: William W
authors.initials: WW
authors.lastname: Adams
mesh_terms: D028202:Abies / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins; D002980:Climate; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D028222:Picea / Q000378:metabolism / Q000502:physiology*; D028223:Pinus / Q000378:metabolism / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D012621:Seasons; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C078410:ELIP protein, Arabidopsis; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D024341:Xanthophylls