title: Low induction of non-photochemical quenching and high photochemical efficiency in the annual desert plant Anastatica hierochuntica.
abstract: Non-photochemical quenching (NPQ) plays a major role in photoprotection. Anastatica hierochuntica is an annual desert plant found in hot deserts. We compared A. hierochuntica to three other different species: Arabidopsis thaliana, Eutrema salsugineum and Helianthus annuus, which have different NPQ and photosynthetic capacities. Anastatica hierochuntica plants had very different induction kinetics of NPQ and, to a lesser extent, of photosystem II electron transport rate (PSII ETR), in comparison to all other plants species in the experiments. The major components of the unusual photosynthetic and photoprotective response in A. hierochuntica were: (1) Low NPQ at the beginning of the light period, at various light intensities and CO2 concentrations. The described low NPQ cannot be explained by low leaf absorbance or by low energy distribution to PSII, but was related to the de-epoxidation state of xanthophylls. (2) Relatively high PSII ETR at various CO2 concentrations in correlation with low NPQ. PSII ETR responded positively to the increase of CO2 concentrations. At low CO2 concentrations PSII ETR was mostly O2 dependent. At moderate and high CO2 concentrations the high PSII ETR in A. hierochuntica was accompanied by relatively high CO2 assimilation rates. We suggest that A. hierochuntica have an uncommon NPQ and PSII ETR response. These responses in A. hierochuntica might represent an adaptation to the short growing season of an annual desert plant.
authors.affiliation: The Albert Katz School for Desert Studies, The Jacob Blaustein Institute for Desert for Desert Research, French Associates Institute for Agriculture and Biotechnology of Drylands, Ben-Gurion university of the Negev, Beersheba, Israel.
authors.forename: Amir
authors.initials: A
authors.lastname: Eppel
authors.forename: Ruth
authors.initials: R
authors.lastname: Shaked
authors.forename: Gil
authors.initials: G
authors.lastname: Eshel
authors.forename: Simon
authors.initials: S
authors.lastname: Barak
authors.forename: Shimon
authors.initials: S
authors.lastname: Rachmilevitch
mesh_terms: D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000494:pharmacology; D019069:Cell Respiration / Q000187:drug effects / Q000528:radiation effects; D003889:Desert Climate; D004579:Electron Transport / Q000187:drug effects / Q000528:radiation effects; D007557:Israel; D008027:Light; D055668:Photochemical Processes / Q000187:drug effects / Q000528:radiation effects; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D027824:Rosaceae / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D024341:Xanthophylls; D002245:Carbon Dioxide; D002244:Carbon