title: Lead uptake increases drought tolerance of wild type and transgenic poplar (Populus tremula x P. alba) overexpressing gsh 1.
abstract: Growth and development of plants largely depends on their adaptation ability in a changing climate. This is particularly true on heavy metal contaminated soils, but the interaction of heavy metal stress and climate on plant performance has not been intensively investigated. The aim of the present study was to elucidate if transgenic poplars (Populus tremula x P. alba) with enhanced glutathione content possess an enhanced tolerance to drought and lead (Pb) exposure (single and in combination) and if they are good candidates for phytoremediation of Pb contaminated soil. Lead exposure reduced growth and biomass accumulation only in above-ground tissue of wild type poplar, although most of lead accumulated in the roots. Drought caused a decline of the water content rather than reduced biomass production, while Pb counteracted this decline in the combined exposure. Apparently, metals such as Pb possess a protective function against drought, because they interact with abscisic acid dependent stomatal closure. Lead exposure decreased while drought increased glutathione content in leaves of both plant types. Lead accumulation was higher in the roots of transgenic plants, presumably as a result of chelation by glutathione. Water deprivation enhanced Pb accumulation in the roots, but Pb was subject to leakage out of the roots after re-watering. Transgenic plants showed better adaptation under mild drought plus Pb exposure partially due to improved glutathione synthesis. However, the transgenic plants cannot be considered as a good candidate for phytoremediation of Pb, due to its small translocation to the shoots and its leakage out of the roots upon re-watering.
authors.affiliation: Chair of Tree Physiology, Faculty of Environment and Natural Resources, University of Freiburg, Georges-Koehler-Allee 53, 79110 Freiburg, Germany.
authors.forename: Sladjana
authors.initials: S
authors.lastname: Samuilov
authors.affiliation: Chair of Soil Ecology, Faculty of Environment and Natural Resources, University of Freiburg, Bertoldstr. 17, 79098 Freiburg, Germany.
authors.forename: Friedericke
authors.initials: F
authors.lastname: Lang
authors.affiliation: Chair of Landscape Horticulture, Faculty of Forestry, University of Belgrade, Kneza Višeslava 1, 11000 Belgrade, Serbia.
authors.forename: Matilda
authors.initials: M
authors.lastname: Djukic
authors.affiliation: Chair of Landscape Horticulture, Faculty of Forestry, University of Belgrade, Kneza Višeslava 1, 11000 Belgrade, Serbia.
authors.forename: Danijela
authors.initials: D
authors.lastname: Djunisijevic-Bojovic
authors.affiliation: Chair of Tree Physiology, Faculty of Environment and Natural Resources, University of Freiburg, Georges-Koehler-Allee 53, 79110 Freiburg, Germany; King Saud University, P.O. Box 2454, Riyadh 11451, Saudi Arabia.
authors.forename: Heinz
authors.initials: H
authors.lastname: Rennenberg
mesh_terms: D000222:Adaptation, Physiological; D001673:Biodegradation, Environmental; D018533:Biomass; D055864:Droughts; D005978:Glutathione; D007854:Lead / Q000737:chemistry / Q000378:metabolism*; D019216:Metals, Heavy / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D018515:Plant Leaves / Q000254:growth & development; D018517:Plant Roots / Q000254:growth & development; D030821:Plants, Genetically Modified; D032107:Populus / Q000235:genetics / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D014867:Water / Q000378:metabolism*
chemical_list: D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D014867:Water; D007854:Lead; D005978:Glutathione
keywords: Glutathione; Pb; Phytoremediation; ROS; Re-watering; Water deprivation