title: Microcystin-tolerant Rhizobium protects plants and improves nitrogen assimilation in Vicia faba irrigated with microcystin-containing waters.
abstract: Irrigation of crops with microcystins (MCs)-containing waters-due to cyanobacterial blooms-affects plant productivity and could be a way for these potent toxins entering the food chain. This study was performed to establish whether MC-tolerant rhizobia could benefit growth, nodulation, and nitrogen metabolism of faba bean plants irrigated with MC-containing waters. For that, three different rhizobial strains-with different sensitivity toward MCs-were used: RhOF96 (most MC-sensitive strain), RhOF125 (most MC-tolerant strain), or Vicz1.1 (reference strain). As a control, plants grown without rhizobia and fertilized by NH4NO3 were included in the study. MC exposure decreased roots (30-37 %) and shoots (up to 15 %) dry weights in un-inoculated plants, whereas inoculation with rhizobia protects plants toward the toxic effects of MCs. Nodulation and nitrogen content were significantly impaired by MCs, with the exception of plants inoculated with the most tolerant strain RhOF125. In order to deep into the effect of inoculation on nitrogen metabolism, the nitrogen assimilatory enzymes (glutamine synthetase (GS) and glutamate synthase (GOGAT)) were investigated: Fertilized plants showed decreased levels (15-30 %) of these enzymes, both in shoots and roots. By contrast, inoculated plants retained the levels of these enzymes in shoots and roots, as well as the levels of NADH-GOGAT activity in nodules. We conclude that the microcystin-tolerant Rhizobium protects faba bean plants and improves nitrogen assimilation when grown in the presence of MCs.
authors: Laboratory of Biology and Biotechnology of Microorganisms, Environmental Microbiology and Toxicology Unit, Faculty of Sciences Semlalia, Cadi Ayyad University, PO Box 2390, Marrakech, Morocco.|Technische Universität Dresden, Institut für Genetik, Helmholtzstr. 10, D-01069, Dresden, Germany.|Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain.
authors: Majida
authors: M
authors: Lahrouni
authors: Laboratory of Biology and Biotechnology of Microorganisms, Environmental Microbiology and Toxicology Unit, Faculty of Sciences Semlalia, Cadi Ayyad University, PO Box 2390, Marrakech, Morocco.
authors: Khalid
authors: K
authors: Oufdou
authors: Laboratory of Biology and Biotechnology of Microorganisms, Environmental Microbiology and Toxicology Unit, Faculty of Sciences Semlalia, Cadi Ayyad University, PO Box 2390, Marrakech, Morocco.|University Hassan 1st. Polydisciplinary Faculty of Khouribga, BP. 145, 25000, Khouribga, Morocco.
authors: Fatima
authors: F
authors: El Khalloufi
authors: Laboratory of Biology and Biotechnology of Microorganisms, Environmental Microbiology and Toxicology Unit, Faculty of Sciences Semlalia, Cadi Ayyad University, PO Box 2390, Marrakech, Morocco.
authors: Loubna
authors: L
authors: Benidire
authors: Technische Universität Dresden, Institut für Genetik, Helmholtzstr. 10, D-01069, Dresden, Germany.
authors: Susann
authors: S
authors: Albert
authors: Technische Universität Dresden, Institut für Genetik, Helmholtzstr. 10, D-01069, Dresden, Germany.
authors: Michael
authors: M
authors: Göttfert
authors: Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain.
authors: Miguel A
authors: MA
authors: Caviedes
authors: Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain.
authors: Ignacio D
authors: ID
authors: Rodriguez-Llorente
authors: Laboratory of Biology and Biotechnology of Microorganisms, Environmental Microbiology and Toxicology Unit, Faculty of Sciences Semlalia, Cadi Ayyad University, PO Box 2390, Marrakech, Morocco.
authors: Brahim
authors: B
authors: Oudra
authors: Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain. epajuelo@us.es.
authors: Eloísa
authors: E
authors: Pajuelo
mesh_terms: D005308:Fertilizers; D005970:Glutamate Synthase / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D052998:Microcystins / Q000633:toxicity*; D009566:Nitrates / Q000494:pharmacology; D009584:Nitrogen / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D012231:Rhizobium; D013559:Symbiosis / Q000187:drug effects; D031307:Vicia faba / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology*; D014873:Water Pollutants / Q000633:toxicity*
chemical_list: D005308:Fertilizers; D052998:Microcystins; D009566:Nitrates; D010940:Plant Proteins; D014873:Water Pollutants; D005970:Glutamate Synthase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen; C006568:ammonium nitrate
keywords: Cyanotoxins; Faba bean; Glutamate synthase; Glutamine synthetase; Nitrogen assimilation; Rhizobia