Laboratory of Biology and Biotechnology of Microorganisms, Environmental Microbiology and Toxicology Unit, Cadi Ayyad University, Faculty of Sciences Semlalia, P.O. Box 2390, Marrakech, Morocco.
Ecotoxicol Environ Saf. 2011 Mar;74(3):431-8. doi: 10.1016/j.ecoenv.2010.10.006. Epub 2010 Oct 27.
The eutrophication of water leads to massive blooms of cyanobacteria potentially producers of highly toxic substances: cyanotoxins, especially microcystins (MC). The contamination of water used for irrigation by these toxins, can cause several adverse effects on plants and microorganisms. In this work, we report the phytotoxic effects of microcystins on the development of symbiosis between the leguminous plant Medicago sativa (Alfalfa) and rhizobia strains. The exposure of rhizobial strains to three different concentrations 0.01, 0.05 and 0.1 μg MC ml(-1) led to decrease on the bacteria growth. The strains of rhizobia Rh L1, Rh L2, Rh L3 and Rh L4 reduced their growth to, respectively, 20.85%, 20.80%, 33.19% and 25.65%. The chronic exposure of alfalfa seeds and seedlings to different MC concentrations affects the whole stages of plant development. The germination process has also been disrupted with an inhibition, which reaches 68.34% for a 22.24 μg MC ml(-1). Further, seedlings growth and photosynthetic process were also disrupted. The toxins reduced significantly the roots length and nodule formation and leads to an oxidative stress. Thus, the MCs contained in lake water and used for irrigation affect the development of symbiosis between M. sativa and Rhizobia.
水体富营养化导致蓝藻大量繁殖，这些蓝藻可能产生剧毒物质：微囊藻毒素（MC）。这些毒素污染灌溉用水会对植物和微生物造成多种不良影响。在这项工作中，我们报告了微囊藻毒素对豆科植物紫花苜蓿（苜蓿）和根瘤菌菌株共生关系发展的植物毒性作用。将根瘤菌菌株暴露于三种不同浓度（0.01、0.05 和 0.1μg MC ml(-1)）下，会导致细菌生长减少。根瘤菌 Rh L1、Rh L2、Rh L3 和 Rh L4 的生长分别减少了 20.85%、20.80%、33.19%和 25.65%。苜蓿种子和幼苗长期暴露于不同的 MC 浓度会影响植物发育的各个阶段。发芽过程也受到了抑制，对于 22.24μg MC ml(-1)的浓度，抑制率达到了 68.34%。此外，幼苗的生长和光合作用也受到了干扰。毒素显著减少了根长和根瘤的形成，并导致氧化应激。因此，湖泊水中所含的 MC 用于灌溉会影响 M. sativa 和 Rhizobia 之间的共生关系的发展。
