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AUTHOR
Jean-françois Briat
Iron acquisition from Fe-pyoverdine by Arabidopsis thaliana.
Taking into account the strong iron competition in the rhizosphere and the high affinity of pyoverdines for Fe(III), these molecules are expected to interfere with the iron nutrition of plants, as they do with rhizospheric microbes. The impact of Fe-pyoverdine on iron content of Arabidopsis thaliana was compared with that of Fe-EDTA. Iron chelated to pyoverdine was incorporated in a more efficient way than when chelated to EDTA, leading to increased plant growth of the wild type. A transgenic line of A. thaliana overexpressing ferritin showed a higher iron content than the wild type when supplemented with Fe-EDTA but a lower iron content when supplemented with Fe-pyoverdine despite its inc…
Reciprocal interactions between plants and fluorescent pseudomonads in relation to iron in the rhizosphere
SPE EA Section 15 : Engineering the rhizosphere: The "biased rhizosphere" concept Ouvrage en 2 volumes Résumé du livre : Molecular Microbial Ecology of the Rhizosphere covers current knowledge on the molecular basis of plant-microbe interactions in the rhizosphere. Also included in the book are both reviews and research-based chapters describing experimental materials and methods. Edited by a leader in the field, with contributions from authors around the world, Molecular Microbial Ecology of the Rhizosphere brings together the most up-to-date research in this expanding area, and will be a valuable resource for molecular microbiologists and plant soil scientists, as well as upper level stud…
Chapter 12 Role of Iron in Plant–Microbe Interactions
Iron is an essential micronutrient for plants and associated microorganisms. Iron nutrition of these organisms relies on the soil supply. However, bioavailability of iron in cultivated soils is low. Plants and microorganisms have thus evolved active strategies of iron uptake based on acidification, chelation, and/or reduction processes. Iron acquisition by these organisms leads to complex interactions ranging from mutualism to competition. In the rhizosphere, plants support abundant and active microbial communities through the release of rhizodeposits. Iron uptake by these microorganisms and by the host plant decrease even more the concentration of iron in solution. Therefore, there is an i…
Flux of protons released by wild type and ferritin over-expressor tobacco plants : effect of phosphorus and iron nutrition
Abstract Tobacco ( Nicotiana tabacum ) plants over-expressing the iron storage protein ferritin, either in the cytoplasm or in the plastids, were grown under various P and Fe conditions. The crossed effects of both the genotypes and the environmental conditions on iron and chlorophyll concentrations in leaves, ferric reductase (EC 1.6.99.13) and plasmalemma H + -ATPase (EC 3.6.3.6) activities in roots, and fluxes of H + released by roots were determined. The increase in leaf Fe concentration observed in plants over-expressing ferritin was accompanied by an increase in root ferric reductase and H + -ATPase activities. Iron deficient conditions induced a decrease in Fe and chlorophyll concent…
Cadmium availability at different soil pH to transgenic tobacco overexpressing ferritin
International audience; Knowledge on physiological mechanisms and plant metabolism can be used to enhance metal uptake. The capacity to uptake metals of transgenic tobaccos overexpressing ferritin in plastids (P6) or in cytoplasm (C5) and a control tobacco (A) is assessed in three polluted soils from the same soil series, with a similar Cd content, but displaying pH from 5.8 to 7 (8b2, 8b3, S11). Differences in dry leave weight were not significant between the three tobaccos growing on each soil. Iron concentration in ferritin overexpression either in P6 or in C5 tobaccos increased only on the S11 soil, which had a soil pH 7, in comparison to A tobacco. In both 8b2 and 8b3 soils at pH lower…
Chapter 4 Iron Dynamics in the Rhizosphere
Abstract Iron is an essential micronutrient for most organisms due to its role in fundamental metabolic processes. In cultivated soils, soil solution iron is mostly oxidized [Fe(III) species] unless local anoxic conditions develop. The concentration of these Fe(III) species is small in soil solution due to the low solubility of ferric oxides, oxyhydroxides, and hydroxides, which is minimal at neutral and alkaline pH. In the rhizosphere, iron concentration in the soil solution is even lower because of its uptake by aerobic organisms (plants and microorganisms), leading to a high level of competition for Fe(III). In order to face iron competition, these organisms have evolved active uptake st…
Tonoplast subcellular localization of maize cytochrome b5 reductases
Plant cytochrome b 5 reductases (b 5 R) are assumed to be part of an ER-associated redox chain that oxidizes NADH to provide electrons via cytochrome b5 (cyt b 5 ) to ER-associated fatty acyl desaturase and related hydroxylases, as in mammalian cells. Here we report on cDNA cloning of a novel maize b 5 R, NFR II, strongly related to a previously cloned cDNA, NFR I (Bagnaresi et al., 1999, Biochem, J. 338, 499-5051. Maize b 5 R isoforms are produced by a small multi-gene family. The NFR cDNAs were shown to encode active b 5 Rs by heterologous expression in yeast. Both reductases, in addition to Fe 3+ -chelates, efficiently reduced Cu 2+ -chelates. Using a polyclonal antibody able to recogniz…
Introduction à l'ouvrage "Les sols et la vie souterraine : des enjeux majeurs en agroécologie"
Cette notice concernant l'introduction de l'ouvrage :"Les sols et la vie souterraine : des enjeux majeurs en agroécologie"SPEEABIOME; Introduction à l'ouvrage "Les sols et la vie souterraine : des enjeux majeurs en agroécologie"
Implication of pyoverdines in the interactions of fluorescent pseudomonads with soil microflora and plant in the rhizosphere
International audience
Reciprocal interactions between plants and fluorescent pseudomonads in relation with iron in the rhizosphere
International audience; Iron is an essential element for plants and microbes. However, in most cultivated soils, the concentration of iron available for these living organisms is very low since its solubility is controlled by stable hydroxides, oxyhydroxides and oxides. The high demand for iron by plants and microorganisms in the rhizosphere together with its low availability in soils leads to a strong competition for this nutrient among living organisms. To face this competition, plants and microorganisms have developed active strategies of iron uptake. In non graminaceous plants (strategy I), iron uptake relies on acidification and reduction of Fe+++ in Fe++ which incorporated in the root…