title: Winter down-regulation of intrinsic photosynthetic capacity coupled with up-regulation of Elip-like proteins and persistent energy dissipation in a subalpine forest.
abstract: Overwintering, sun-exposed and photosynthetically inactive evergreens require powerful photoprotection. The goal of this study was to seasonally characterize photosynthesis and key proteins/components involved in electron transport and photoprotection. Maximal photosystem II (PSII) efficiency and photosynthetic capacity, amounts of zeaxanthin (Z), antheraxanthin (A), pheophytin and proteins (oxygen-evolving 33 kDa protein (OEC), PSII core protein D1 and subunit S (PsbS) protein, and members of the early light-inducible protein (Elip) family) were assessed in five conifer species at high altitude and in ponderosa pine (Pinus ponderosa) at moderate altitude during summer and winter. Relative to summer, winter down-regulation of photosynthetic capacity and loss of PSII efficiency at the high-altitude sites were paralleled by decreases in OEC, D1, and pheophytin; massive nocturnal retention of (Z + A) and up-regulation of two to four proteins cross-reactive with anti-Elip antibodies; and no change in PsbS amount. By contrast, ponderosa pine at moderate altitude exhibited no down-regulation of photosynthetic capacity, smaller depressions in PSII efficiency, and less up-regulation of Elip family members. These results support a function for members of the Elip family in the acclimation of sun-exposed needles that down-regulate photosynthesis during winter. A possible role in sustained photoprotection is considered.
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: William W
authors.initials: WW
authors.lastname: Adams
authors.forename: Volker
authors.initials: V
authors.lastname: Ebbert
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Cuthbertson
authors.forename: Iwona
authors.initials: I
authors.lastname: Adamska
authors.forename: Barbara
authors.initials: B
authors.lastname: Demmig-Adams
mesh_terms: D000531:Altitude; D029681:Arabidopsis Proteins; D003080:Cold Temperature; D017753:Ecosystem; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005810:Multigene Family; D010788:Photosynthesis / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D041604:Pinus ponderosa / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D012621:Seasons; D013472:Sunlight; D064028:Tracheophyta / Q000378:metabolism*; D014197:Trees / Q000378:metabolism*; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C078410:ELIP protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D024341:Xanthophylls