title: Winter acclimation of PsbS and related proteins in the evergreen Arctostaphylos uva-ursi as influenced by altitude and light environment.
abstract: The evergreen groundcover bearberry (Arctostaphylos uva-ursi [L.] Sprengel) was characterized over two successive years (2002-2004) from both sun-exposed and shaded sites at a montane ponderosa pine and subalpine forest community of 1900- and 2800-m-high altitudes, respectively. During summer, photosynthetic capacities and pre-dawn photosystem II (PSII) efficiency were similarly high in all four populations, and in winter, only the sun-exposed and shaded populations at 2800 m exhibited complete down-regulation of photosynthetic oxygen evolution capacity and consistent sustained down-regulation of PSII efficiency. This photosynthetic down-regulation at high altitude involved a substantial decrease in PSII components [pheophytin, D1 protein, oxygen evolving complex ([OEC)], a strong up-regulation of several anti-early-light-inducible protein (Elip)- and anti-high-light-inducible protein (Hlip)-reactive bands and a warm-sustained retention of zeaxanthin and antheraxanthin (Z + A). PsbS, the protein modulating the rapid engagement and disengagement of Z +A in energy dissipation, exhibited its most pronounced winter increases in the shade at 1900 m, and thus apparently assumes a greater role in providing rapidly reversible zeaxanthin-dependent photoprotection during winter when light becomes excessive in the shaded population, which remains photosynthetically active. It is attractive to hypothesize that PsbS relatives (Elips/Hlips) may be involved in sustained zeaxanthin-dependent photoprotection under the more extreme winter conditions at 2800 m.
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: Iwona
authors.initials: I
authors.lastname: Adamska
authors.forename: Stefan
authors.initials: S
authors.lastname: Jansson
authors.forename: Barbara
authors.initials: B
authors.lastname: Demmig-Adams
mesh_terms: D000222:Adaptation, Physiological; D000531:Altitude; D029681:Arabidopsis Proteins / Q000378:metabolism*; D029792:Arctostaphylos / Q000378:metabolism / Q000502:physiology*; D003080:Cold Temperature; D004591:Electrophoresis, Polyacrylamide Gel; D005453:Fluorescence; D008027:Light; D045342:Light-Harvesting Protein Complexes; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D012621:Seasons
chemical_list: D029681:Arabidopsis Proteins; D045342:Light-Harvesting Protein Complexes; C489731:NPQ4 protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex