title: Phytotoxicity of cobalt ions on the duckweed Lemna minor - Morphology, ion uptake, and starch accumulation.
abstract: Cobalt (Co2+) inhibits vegetative growth of Lemna minor gradually from 1 μM to 100 μM. Fronds accumulated up to 21 mg Co2+ g(-1) dry weight at 10 μM external Co2+ indicating hyperaccumulation. Interestingly, accumulation of Co2+ did not decrease the iron (Fe) content in fronds, highlighting L. minor as a suitable system for studying effects of Co2+ undisturbed by Fe deficiency symptoms unlike most other plants. Digital image analysis revealed the size distribution of fronds after Co2+ treatment and also a reduction in pigmentation of newly formed daughter fronds unlike the mother fronds during the 7-day treatment. Neither chlorophyll nor photosystem II fluorescence changed significantly during the initial 4d, indicating effective photosynthesis. During the later phase of the 7-day treatment, however, chlorophyll content and photosynthetic efficiency decreased in the Co2+-treated daughter fronds, indicating that Co2+ inhibits the biosynthesis of chlorophyll rather than leading to the destruction of pre-existing pigment molecules. In addition, during the first 4d of Co2+ treatment starch accumulated in the fronds and led to the transition of chloroplasts to chloro-amyloplasts and amylo-chloroplasts, while starch levels strongly decreased thereafter.
authors.affiliation: Amity University Uttar Pradesh, Amity Institute of Microbial Technology, Noida, India.
authors.forename: K Sowjanya
authors.initials: KS
authors.lastname: Sree
authors.affiliation: Eötvös Loránd University, Department of Plant Anatomy, Budapest, Hungary.
authors.forename: Áron
authors.initials: Á
authors.lastname: Keresztes
authors.affiliation: University of Potsdam, Molecular Biology, Potsdam, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Mueller-Roeber
authors.affiliation: University of Jena, Institute of Plant Physiology, Jena, Germany; Leibniz Institute of Plant Genetics and Crop Plant Research, Stadt Seeland, Germany.
authors.forename: Ronny
authors.initials: R
authors.lastname: Brandt
authors.affiliation: LemnaTec GmbH, Aachen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Eberius
authors.affiliation: University of Jena, Institute of Plant Physiology, Jena, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Fischer
authors.affiliation: University of Jena, Institute of Plant Physiology, Jena, Germany. Electronic address: Klaus.Appenroth@uni-jena.de.
authors.forename: Klaus-J
authors.initials: KJ
authors.lastname: Appenroth
mesh_terms: D029064:Araceae / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism*; D050260:Carbohydrate Metabolism / Q000187:drug effects; D003035:Cobalt / Q000633:toxicity*; D007477:Ions / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D013213:Starch / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D007477:Ions; D014874:Water Pollutants, Chemical; D003035:Cobalt; D013213:Starch
keywords: Chloroplast; Cobalt; Lemna minor; Lemnaceae; Phytotoxicity; Starch accumulation