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Saint-Étienne, France

Gerbore J.,CNRS Agroecology Lab | Gerbore J.,University of Pau and Pays de lAdour | Vallance J.,CNRS Agroecology Lab | Vallance J.,University of Bordeaux 1 | And 8 more authors.
FEMS Microbiology Ecology

This study focused on one oomycete, Pythium oligandrum, well-known for its plant protection abilities, which thrives in microbial environment where bacteria and fungal communities are also present. The genetic structures and dynamics of fungal and bacterial communities were studied in three Bordeaux subregions with various types of soil, using single-strand conformation polymorphism. The structure of the fungal communities colonizing the rhizosphere of vines planted in sandy-stony soils was markedly different from that those planted in silty and sandy soils; such differences were not observed for bacteria. In our 2-year experiment, the roots of all the vine samples were also colonized by echinulated oospore Pythium species, with P. oligandrum predominating. Cytochrome oxidase I and tubulin gene sequencings showed that P. oligandrum strains clustered into three groups. Based on elicitin-like genes coding for proteins able to induce plant resistance, six populations were identified. However, none of these groups was assigned to a particular subregion of Bordeaux vineyards, suggesting that these factors do not shape the genetic structure of P. oligandrum populations. Results showed that different types of rootstock and weeding management both influence root colonization by P. oligandrum. These results should prove particularly useful in improving the management of potentially plant-protective microorganisms. Pythium oligandrum strains with elicitor genes frequently colonize grapevine rhizosphere and the genetic structure of strains is not shaped by the abiotic and biotic factors studied in three Bordeaux sub-regions. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved. Source

Gerbore J.,CNRS Agroecology Lab | Gerbore J.,University of Pau and Pays de lAdour | Vallance J.,CNRS Agroecology Lab | Vallance J.,University of Bordeaux 1 | And 5 more authors.
Environmental Science and Pollution Research

The management of certain plant beneficial microorganisms [biological control agents (BCAs)] seems to be a promising and environmental friendly method to control plant pathogens. However, applications are still limited because of the lack of consistency of BCAs when they are applied in the field. In the present paper, the advantages and limitations of BCAs are seen through the example of Pythium oligandrum, an oomycete that has received much attention in the last decade. The biological control exerted by P. oligandrum is the result of a complex process, which includes direct effects through the control of pathogens and/or indirect effects mediated by P. oligandrum, i.e. induction of resistance and growth promotion. P. oligandrum antagonism is a multifaceted and target fungus-dependent process. Interestingly, it does not seem to disrupt microflora biodiversity on the roots. P. oligandrum has an atypical relationship with the plant because it rapidly penetrates into the root tissues but it cannot stay alive in planta. After root colonisation, because of the elicitation by P. oligandrum of the plant-defence system, plants are protected from a range of pathogens. The management of BCAs, here P. oligandrum, is discussed with regard to its interactions with the incredibly complex agrosystems. © 2013 Springer-Verlag Berlin Heidelberg. Source

Yacoub A.,CNRS Agroecology Lab | Yacoub A.,University of Bordeaux 1 | Yacoub A.,University of Pau and Pays de lAdour | Gerbore J.,BIOVITIS | And 10 more authors.
Biological Control

Biological control of Phaeomoniella chlamydospora, a pathogen involved in Esca, a grapevine trunk wood disease, was performed using the oomycete, Pythium oligandrum. Three 4-month greenhouse assays showed that necrosis of Vitis vinifera L. cv. Cabernet Sauvignon cuttings caused by P. chlamydospora was significantly reduced (40-50%) when P. oligandrum colonized the plant root systems. The expression of a set of 22 grapevine defense genes was then quantified by real-time polymerase chain reaction to determine plant responses in the interaction between P. oligandrum/. V. vinifera L./. P. chlamydospora. In the trunk, specific grapevine responses to the different treatments (control, P. oligandrum, P. chlamydospora and P. oligandrum+. P. chlamydospora treatments) were significantly differentiated. Expression levels of 6 genes associated with P. chlamydospora infection showed higher induction than when plants were pre-treated with P. oligandrum. These genes are involved in various pathways (PR proteins, phenylpropanoid pathways, oxylipin and oxydo-reduction systems). © 2015 Elsevier Inc. Source

Bouchiat R.,University of the Littoral Opal Coast | Veignie E.,University of the Littoral Opal Coast | Grizard D.,BIOVITIS | Soebert C.,BIOVITIS | And 2 more authors.
Desalination and Water Treatment

This study was conducted to investigate biodegradation of four emergent water priority pollutants, di(2-ethylhexyl)phthalate (DEHP), fluoranthene, aminomethylphosphonic acid (AMPA), and estrone (EST), by filamentous fungi (Fusarium oxysporum, Geotrichum galactomyces, Trichoderma harzianum, and Fusarium solani). These pollutants are commonly found at high occurrence in French wastewater treatment plants. In acute toxicity tests, a weak sensitivity of fungal growth to the pollutants was observed with F. oxysporum showing the greatest growth inhibition (19.3%) in the presence of DEHP after four days of incubation. In addition, degradation experiments were conducted in mineral medium for each pollutant incubated with each filamentous fungus for 10 d. With the exception of EST, which was not degraded by any fungal isolate tested, the fungi degraded these emergent water priority pollutants, with F. solani and T. harzianum degrading 100% of DEHP and 69% of AMPA, respectively. © 2015 Balaban Desalination Publications. All rights reserved. Source

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