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@article{635688, author = {Hájek, Josef and Barták, Miloš and Dubová, Jaroslava}, article_location = {Dordrecht}, article_number = {4}, keywords = {photosynthesis; water potential; dehydration; Lasallia pustulata; Umbilicaria hirsuta; sucrose; chlorophyll fluorescence; thallus anatomy}, language = {eng}, issn = {0006-3134}, journal = {Biologia Plantarum}, note = {accepted 17 October 2005}, title = {Inhibition of photosynthetic processes in foliose lichens induced by temperature and osmotic stress.}, volume = {50}, year = {2006} }
TY - JOUR ID - 635688 AU - Hájek, Josef - Barták, Miloš - Dubová, Jaroslava PY - 2006 TI - Inhibition of photosynthetic processes in foliose lichens induced by temperature and osmotic stress. JF - Biologia Plantarum VL - 50 IS - 4 SP - 624-634 EP - 624-634 PB - KLUWER ACADEMIC PUBLISHERS SN - 00063134 N1 - accepted 17 October 2005 KW - photosynthesis KW - water potential KW - dehydration KW - Lasallia pustulata KW - Umbilicaria hirsuta KW - sucrose KW - chlorophyll fluorescence KW - thallus anatomy N2 - Negative effects of osmotically-induced dehydration of two foliose lichen species, Lasallia pustulata and Umbilicaria hirsuta, was studied at physiological (22 deg C), low (5 deg C) and freezing temperature (-10 deg C), using chlorophyll (Chl) fluorescence. In both species, exposition to increasing sucrose concentrations led to a pronounced decrease in potential (FV/FM), and actual (Fi2) quantum yields of photochemical processes in photosystem 2. Lasallia pustulata was more sensitive to osmotic stress, because comparable osmotic dehydration inhibited FV/FM, Fi2 more than in Umbilicaria hirsuta. In our study, critical concentration of sucrose that fully inhibited photochemical processes of photosynthesis was 2.5 M, which represented water potential (ŁZ) of ĄV18.8 MPa. Decrease in background Chl fluorecsence (F0) and increase in non-photochemical quenching (qN) revealed two phases of osmotic stress in lichens: phase I with no change (ŁZ 0 to -6.6 MPa) and phase II (ŁZ -11.3 to -18.8 MPa) typical by substantial change in Chl fluorescence parameters. Effects of thallus anatomy on species-specific response to osmotic dehydration is discussed and attributed to results obtained by optical microscopy and Chl fluorescence imaging technique. ER -
HÁJEK, Josef, Miloš BARTÁK and Jaroslava DUBOVÁ. Inhibition of photosynthetic processes in foliose lichens induced by temperature and osmotic stress. \textit{Biologia Plantarum}. Dordrecht: KLUWER ACADEMIC PUBLISHERS, 2006, vol.~50, No~4, p.~624-634, 10 pp. ISSN~0006-3134.
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