Toxic effects of arsenic on Sinorhizobium-Medicago sativa symbiotic interaction.
Recently, the Rhizobium-legume symbiotic interaction has been proposed as an interesting tool in bioremediation. However, little is known about the effect of most common contaminants on this process. The phytotoxic effects of arsenic on nodulation of Medicago sativa have been examined in vitro using the highly arsenic resistant and symbiotically effective Sinorhizobium sp. strain MA11. The bacteria were able to grow on plates containing As concentrations as high as 10 mM. Nevertheless, as little as 25-35 microM arsenite produced a 75% decrease in the total number of nodules, due to a 90% reduction in the number of rhizobial infections, as could be determined using the strain MA11 carrying a lacZ reporter gene. This effect was associated to root hair damage and a shorter infective root zone. However, once nodulation was established nodule development seemed to continue normally, although earlier senescence could be observed in nodules of arsenic-grown plants.
Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain.
Eloísa
E
Pajuelo
Ignacio D
ID
Rodríguez-Llorente
Mohammed
M
Dary
Antonio J
AJ
Palomares
D001151:Arsenic / Q000633:toxicity*; D001673:Biodegradation, Environmental; D002274:Carcinogens, Environmental / Q000633:toxicity*; D004463:Ecology / Q000379:methods; D000455:Medicago sativa / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology; D009586:Nitrogen Fixation; D053204:Root Nodules, Plant / Q000187:drug effects / Q000254:growth & development; D020579:Sinorhizobium / Q000187:drug effects* / Q000378:metabolism; D012989:Soil Pollutants / Q000633:toxicity*; D013559:Symbiosis / Q000187:drug effects
D002274:Carcinogens, Environmental; D012989:Soil Pollutants; D001151:Arsenic