title: Simulated soil crust conditions in a chamber system provide new insights on cyanobacterial acclimation to desiccation.
abstract: Environmental research often faces two major hurdles: (i) fluctuating spatial and temporal conditions and consequently large variability in the organisms' abundance and performance, and (ii) complex, costly logistics involved in field experiments. Measurements of physiological parameters or molecular analyses often represent single shot experiments. To study desiccation acclimation of filamentous cyanobacteria, the founders and main primary producers in desert biological soil crusts (BSC), we constructed an environmental chamber that can reproducibly and accurately simulate ambient conditions and measure microorganism performance. We show that recovery from desiccation of BSC cyanobacteria and Leptolyngbya ohadii isolated thereof are strongly affected by dehydration rate following morning dew. This effect is most pronounced in cells exposed to high light and temperature in the dry phase. Simultaneous measurements of water content, gas exchange and fluorescence were performed during dehydration. Photosynthetic performance measured by fluorescence begins declining when light intensity reaches values above 100 μmol photons m(-2) s(-1), even in fully hydrated cells. In contrast, photosynthetic rates measured using O2 evolution and CO2 uptake increased during rising irradiance to the point where the water content declined below ∼ 50%. Thus, fluorescence cannot serve as a reliable measure of photosynthesis in desert cyanobacteria. The effects of drying on gas exchange are discussed.
authors.affiliation: Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
authors.forename: Hagai
authors.initials: H
authors.lastname: Raanan
authors.affiliation: Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
authors.forename: Nadav
authors.initials: N
authors.lastname: Oren
authors.affiliation: Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
authors.forename: Haim
authors.initials: H
authors.lastname: Treves
authors.affiliation: Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.|Arid Ecosystems Research Center, Edmond J. Safra Campus, Givat Ram, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Berkowicz
authors.affiliation: Institut für Biowissenschaften, Abteilung Pflanzenphysiologie, Universität Rostock, A.-Einstein-Str. 3, Rostock, D-18059, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Hagemann
authors.affiliation: Institut für Biowissenschaften, Abteilung Pflanzenphysiologie, Universität Rostock, A.-Einstein-Str. 3, Rostock, D-18059, Germany.
authors.forename: Nadin
authors.initials: N
authors.lastname: Pade
authors.affiliation: Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Keren
authors.affiliation: Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.|Arid Ecosystems Research Center, Edmond J. Safra Campus, Givat Ram, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
authors.forename: Aaron
authors.initials: A
authors.lastname: Kaplan
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D001692:Biological Transport; D000458:Cyanobacteria / Q000502:physiology*; D003681:Dehydration / Q000378:metabolism*; D003889:Desert Climate; D003890:Desiccation; D005453:Fluorescence; D008027:Light; D010788:Photosynthesis / Q000502:physiology*; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013696:Temperature; D014199:Trehalose / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D012987:Soil; D014867:Water; D014199:Trehalose