Changes in macromolecular allocation in nondividing algal symbionts allow for photosynthetic acclimation in the lichen Lobaria pulmonaria

Authors

  • Scott C. Schofield,

    1. Department of Biology and Coastal Wetlands Institute, Mount Allison University, Sackville, New Brunswick, E4L 1G7, Canada;
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  • Douglas A. Campbell,

    Corresponding author
    1. Department of Biology and Coastal Wetlands Institute, Mount Allison University, Sackville, New Brunswick, E4L 1G7, Canada;
    2. Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 6E1, Canada;
      Author for correspondence: Douglas A. Campbell Tel: +1 506 364 2521 Fax: +1 506 364 2505 Email: dcampbell@mta.ca
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  • Christiane Funk,

    1. Department of Biochemistry and Umeå Plant Science Center (UPSC), Umeå University, SE-901 87 Umeå, Sweden
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  • Tyler D. B. MacKenzie

    1. Department of Biology and Coastal Wetlands Institute, Mount Allison University, Sackville, New Brunswick, E4L 1G7, Canada;
    2. Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 6E1, Canada;
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Author for correspondence: Douglas A. Campbell Tel: +1 506 364 2521 Fax: +1 506 364 2505 Email: dcampbell@mta.ca

Summary

  • •   The lichen Lobaria pulmonaria survives large seasonal environmental changes through physiological acclimation to ambient conditions.
  • •   We quantitated algal cell population, cell division and key macromolecular levels associated with photosynthesis and nitrogen metabolism in L. pulmonaria sampled from four seasons with contrasting environmental conditions in a deciduous forest.
  • •   The algal symbiont population did not vary seasonally and cell division was restricted to the newest thallus margins. Nevertheless the symbiont concentrations of chlorophyll, PsbS, PsbA, and RbcL changed significantly through the seasons in the nondividing algal cells from older thallus regions.
  • •   L. pulmonaria reversibly allocated resources toward photochemical electron generation and carbohydrate production through the spring, summer and fall, and towards photoprotective dissipation in the cold, high-light winter. Our study shows that large seasonal molecular acclimation in L. pulmonaria occurs within a nearly stable, nondividing algal cell population that maintains photosynthetic capacity through many years of changing environmental cues.

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