Publications by authors named "Diederik van Tuinen"

30 Publications

  • Page 1 of 1

Development of a taxon-discriminating molecular marker to trace and quantify a mycorrhizal inoculum in roots and soils of agroecosystems.

Folia Microbiol (Praha) 2021 Jun 3;66(3):371-384. Epub 2021 Feb 3.

Agroécologie, AgroSup Dijon, CNRS, Université Bourgogne, INRAE, Université Bourgogne Franche-Comté, 21000, Dijon, France.

Crop inoculation with Glomus cubense isolate (INCAM-4, DAOM-241198) promotes yield in banana, cassava, forages, and others. Yield improvements range from 20 to 80% depending on crops, nutrient supply, and edaphoclimatic conditions. However, it is difficult to connect yield effects with G. cubense abundance in roots due to the lack of an adequate methodology to trace this taxon in the field. It is necessary to establish an accurate evaluation framework of its contribution to root colonization separated from native arbuscular mycorrhizal fungi (AMF). A taxon-discriminating primer set was designed based on the ITS nrDNA marker and two molecular approaches were optimized and validated (endpoint PCR and quantitative real-time PCR) to trace and quantify the G. cubense isolate in root and soil samples under greenhouse and environmental conditions. The detection limit and specificity assays were performed by both approaches. Different 18 AMF taxa were used for endpoint PCR specificity assay, showing that primers specifically amplified the INCAM-4 isolate yielding a 370 bp-PCR product. In the greenhouse, Urochloa brizantha plants inoculated with three isolates (Rhizophagus irregularis, R. clarus, and G. cubense) and environmental root and soil samples were successfully traced and quantified by qPCR. The AMF root colonization reached 41-70% and the spore number 4-128 per g of soil. This study demonstrates for the first time the feasibility to trace and quantify the G. cubense isolate using a taxon-discriminating ITS marker in roots and soils. The validated approaches reveal their potential to be used for the quality control of other mycorrhizal inoculants and their relative quantification in agroecosystems.
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http://dx.doi.org/10.1007/s12223-020-00844-yDOI Listing
June 2021

Correction to: Tracing Rhizophagus irregularis isolate IR27 in Ziziphus mauritiana roots under field conditions.

Mycorrhiza 2020 01;30(1):171

Laboratoire des Symbioses Tropicales et Méditerranéennes UMR113 INRA/AGRO-M/CIRAD/IRD/UM2-TA10/J, Campus International de Baillarguet, 34398, Montpellier, France.

The authors of the above-mentioned published article inadvertently omitted Dirk Redecker, Dioumacor Fall and Diaminatou Sanogo from the list of authors. The names and their affiliations presented in this paper.
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http://dx.doi.org/10.1007/s00572-020-00935-1DOI Listing
January 2020

Trading on the arbuscular mycorrhiza market: from arbuscules to common mycorrhizal networks.

New Phytol 2019 08 1;223(3):1127-1142. Epub 2019 Apr 1.

Agroécologie, AgroSup Dijon, CNRS, Univ. Bourgogne, INRA, Univ. Bourgogne Franche-Comté, F-21000, Dijon, France.

Arbuscular mycorrhiza (AM) symbiosis occurs between obligate biotrophic fungi of the phylum Glomeromycota and most land plants. The exchange of nutrients between host plants and AM fungi (AMF) is presumed to be the main benefit for the two symbiotic partners. In this review article, we outline the current concepts of nutrient exchanges within this symbiosis (mechanisms and regulation). First, we focus on phosphorus and nitrogen transfer from the fungal partner to the host plant, and on the reciprocal transfer of carbon compounds, with a highlight on a possible interplay between nitrogen and phosphorus nutrition during AM symbiosis. We further discuss potential mechanisms of regulation of these nutrient exchanges linked to membrane dynamics. The review finally addresses the common mycorrhizal networks formed AMF, which interconnect plants from similar and/or different species. Finally the best way to integrate this knowledge and the ensuing potential benefits of AM into sustainable agriculture is discussed.
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http://dx.doi.org/10.1111/nph.15775DOI Listing
August 2019

Tracing Rhizophagus irregularis isolate IR27 in Ziziphus mauritiana roots under field conditions.

Mycorrhiza 2019 Jan 21;29(1):77-83. Epub 2018 Nov 21.

Laboratoire des Symbioses Tropicales et Méditerranéennes UMR113 INRA/AGRO-M/CIRAD/IRD/UM2-TA10/J, Campus International de Baillarguet, 34398, Montpellier, France.

Arbuscular mycorrhizal fungi (AMF) play a major role as biofertilizer for sustainable agriculture. Nevertheless, it is still poorly documented whether inoculated AMF can successfully establish in field soils as exotic AMF and improve plant growth and productivity. Further, the fate of an exogenous inoculum is still poorly understood. Here, we pre-inoculated two cultivars (Tasset and Gola) of the fruit tree Ziziphus mauritiana (jujube) with the exotic AM fungus Rhizophagus irregularis isolate IR27 before transplantation in the field. In two experiments, tracking and quantification of R. irregularis IR27 were assessed in a 13-month-old jujube and an 18-month-old jujube in two fields located in Senegal. Our results showed that the inoculant R. irregularis IR27 was quantitatively traced and discriminated from native R. irregularis isolates in roots by using a qPCR assay targeting a fragment of the RNA polymerase II gene (RPB1), and that the inoculum represented only fractions ranging from 11 to 15% of the Rhizophagus genus in the two plantations 13 and 18 months after transplantation, respectively. This study validates the use of the RPB1 gene as marker for a relative quantification of a mycorrhizal inoculant fungus isolate in the field.
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http://dx.doi.org/10.1007/s00572-018-0875-3DOI Listing
January 2019

Differential Signaling and Sugar Exchanges in Response to Avirulent Pathogen- and Symbiont-Derived Molecules in Tobacco Cells.

Front Microbiol 2017 20;8:2228. Epub 2017 Nov 20.

Agroécologie, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, Dijon, France.

Plants interact with microbes whose ultimate aim is to exploit plant carbohydrates for their reproduction. Plant-microbe interactions (PMIs) are classified according to the nature of their trophic exchanges: while mutualistic microbes trade nutrients with plants, pathogens unilaterally divert carbohydrates. The early responses following microbe recognition and the subsequent control of plant sugar distribution are still poorly understood. To further decipher PMI functionality, we used tobacco cells treated with microbial molecules mimicking pathogenic or mutualistic PMIs, namely cryptogein, a defense elicitor, and chitotetrasaccharide (CO4), which is secreted by mycorrhizal fungi. CO4 was perceived by tobacco cells and triggered widespread transient signaling components such as a sharp cytosolic Ca elevation, NtrbohD-dependent HO production, and MAP kinase activation. These CO4-induced events differed from those induced by cryptogein, i.e., sustained events leading to cell death. Furthermore, cryptogein treatment inhibited glucose and sucrose uptake but not fructose uptake, and promoted the expression of and sugar transporters, whereas CO4 had no effect on sugar uptake and only a slight effect on expression. Our results suggest that microbial molecules induce different signaling responses that reflect microbial lifestyle and the subsequent outcome of the interaction.
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http://dx.doi.org/10.3389/fmicb.2017.02228DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5701941PMC
November 2017

Impact of a pesticide cocktail (fenhexamid, folpel, deltamethrin) on the abundance of Glomeromycota in two agricultural soils.

Sci Total Environ 2017 Jan 4;577:84-93. Epub 2016 Nov 4.

Agroécologie, AgroSup Dijon, INRA, Univ. Bourgogne Franche-Comté, Dijon, France.

Pesticide contamination of the environment can result from agricultural practices. Persistence of pesticide residues is a threat to the soil biota including plant roots and beneficial microorganisms, which support an important number of soil ecosystem services. Arbuscular mycorrhizal fungi (AMF) are key symbiotic microorganisms contributing to plant nutrition. In the present study, we assessed whether AMF could indicate eventual side effects of pesticides when directly applied to field soils. We evaluated the ecotoxicological impact of a cocktail of three commonly used agricultural pesticides (fenhexamid, folpel, deltamethrin) on the abundance and composition of the AMF community in vineyard (Montagne de Saint-Emilion) and arable (Martincourt) soils subjected to different agricultural practices. The dissipation of applied pesticides was monitored by multiresidual analyses to determine the scenario of exposure of the AMF community. Diversity analysis before application of the pesticide cocktail showed that the AMF communities of vineyard soils, subjected to mechanical weeding or grass cover, and of the arable soil subjected to intensive agriculture, were dominated by Glomerales. Ribotypes specific to each soil and to each agricultural practice in the same soil were found, with the highest abundance and diversity of AMF being observed in the vineyard soil with a grass-cover. The abundance of the global AMF community (Glomeromycota) and of three taxa of AMF (Funneliformis mosseae, Claroideoglomus etunicatum/C. claroideum) was evaluated after pesticide application. The abundance of Glomeromycota decreased in both soils after pesticide application while the abundance of Claroideoglomus and F. mosseae decreased only in the arable soil. These results show that higher doses of pesticide exposure did not affect the global abundance, but altered the composition, of the AMF community. Resilience of the AMF community composition was observed only in the vineyard soil, where F. mosseae was the most tolerant taxon to pesticide exposure.
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http://dx.doi.org/10.1016/j.scitotenv.2016.10.098DOI Listing
January 2017

Transcriptional responses of Medicago truncatula upon sulfur deficiency stress and arbuscular mycorrhizal symbiosis.

Front Plant Sci 2014 2;5:680. Epub 2014 Dec 2.

UMR 1347 Agroécologie, Pôle Interactions Plantes-Microorganismes - ERL 6300 CNRS, Université de Bourgogne Dijon, France.

Sulfur plays an essential role in plants' growth and development and in their response to various abiotic and biotic stresses despite its leachability and its very low abundance in the only form that plant roots can uptake (sulfate). It is part of amino acids, glutathione (GSH), thiols of proteins and peptides, membrane sulfolipids, cell walls and secondary products, so reduced availability can drastically alter plant growth and development. The nutritional benefits of symbiotic interactions can help the plant in case of S deficiency. In particular the arbuscular mycorrhizal (AM) interaction improves N, P, and S plant nutrition, but the mechanisms behind these exchanges are not fully known yet. Although the transcriptional changes in the leguminous model plant Medicago truncatula have been already assessed in several biotic and/or abiotic conditions, S deficiency has not been considered so far. The aim of this work is to get a first overview on S-deficiency responses in the leaf and root tissues of plants interacting with the AM fungus Rhizophagus irregularis. Several hundred genes displayed significantly different transcript accumulation levels. Annotation and GO ID association were used to identify biological processes and molecular functions affected by sulfur starvation. Beside the beneficial effects of AM interaction, plants were greatly affected by the nutritional status, showing various differences in their transcriptomic footprints. Several pathways in which S plays an important role appeared to be differentially affected according to mycorrhizal status, with a generally reduced responsiveness to S deficiency in mycorrhized plants.
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http://dx.doi.org/10.3389/fpls.2014.00680DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4251294PMC
December 2014

The membrane proteome of Medicago truncatula roots displays qualitative and quantitative changes in response to arbuscular mycorrhizal symbiosis.

J Proteomics 2014 Aug 10;108:354-68. Epub 2014 Jun 10.

Environmental and Agro-Biotechnologies Department, Centre de Recherche Public-Gabriel Lippmann, 41, rue du Brill, Belvaux L-4422, Luxembourg. Electronic address:

Unlabelled: Arbuscular mycorrhizal (AM) symbiosis that associates roots of most land plants with soil-borne fungi (Glomeromycota), is characterized by reciprocal nutritional benefits. Fungal colonization of plant roots induces massive changes in cortical cells where the fungus differentiates an arbuscule, which drives proliferation of the plasma membrane. Despite the recognized importance of membrane proteins in sustaining AM symbiosis, the root microsomal proteome elicited upon mycorrhiza still remains to be explored. In this study, we first examined the qualitative composition of the root membrane proteome of Medicago truncatula after microsome enrichment and subsequent in depth analysis by GeLC-MS/MS. The results obtained highlighted the identification of 1226 root membrane protein candidates whose cellular and functional classifications predispose plastids and protein synthesis as prevalent organelle and function, respectively. Changes at the protein abundance level between the membrane proteomes of mycorrhizal and nonmycorrhizal roots were further monitored by spectral counting, which retrieved a total of 96 proteins that displayed a differential accumulation upon AM symbiosis. Besides the canonical markers of the periarbuscular membrane, new candidates supporting the importance of membrane trafficking events during mycorrhiza establishment/functioning were identified, including flotillin-like proteins. The data have been deposited to the ProteomeXchange with identifier PXD000875.

Biological Significance: During arbuscular mycorrhizal symbiosis, one of the most widespread mutualistic associations in nature, the endomembrane system of plant roots is believed to undergo qualitative and quantitative changes in order to sustain both the accommodation process of the AM fungus within cortical cells and the exchange of nutrients between symbionts. Large-scale GeLC-MS/MS proteomic analysis of the membrane fractions from mycorrhizal and nonmycorrhizal roots of M. truncatula coupled to spectral counting retrieved around one hundred proteins that displayed changes in abundance upon mycorrhizal establishment. The symbiosis-related membrane proteins that were identified mostly function in signaling/membrane trafficking and nutrient uptake regulation. Besides extending the coverage of the root membrane proteome of M. truncatula, new candidates involved in the symbiotic program emerged from the current study, which pointed out a dynamic reorganization of microsomal proteins during the accommodation of AM fungi within cortical cells.
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http://dx.doi.org/10.1016/j.jprot.2014.05.028DOI Listing
August 2014

The Medicago truncatula hypermycorrhizal B9 mutant displays an altered response to phosphate and is more susceptible to Aphanomyces euteiches.

Plant Cell Environ 2015 Jan 2;38(1):73-88. Epub 2014 Jun 2.

INRA/AgroSup/Université de Bourgogne UMR1347 Agroécologie, ERL CNRS 6300, Dijon, F-21065, France.

Inorganic phosphate (Pi) plays a key role in the development of arbuscular mycorrhizal (AM) symbiosis, which is favoured when Pi is limiting in the environment. We have characterized the Medicago truncatula hypermycorrhizal B9 mutant for its response to limiting (P/10) and replete (P2) Pi. On P2, mycorrhization was significantly higher in B9 plants than in wild-type (WT). The B9 mutant displayed hallmarks of Pi-limited plants, including higher levels of anthocyanins and lower concentrations of Pi in shoots than WT plants. Transcriptome analyses of roots of WT and B9 plants cultivated on P2 or on P/10 confirmed the Pi-limited profile of the mutant on P2 and highlighted its altered response to Pi on P/10. Furthermore, the B9 mutant displayed a higher expression of defence/stress-related genes and was more susceptible to infection by the root oomycete pathogen Aphanomyces euteiches than WT plants. We propose that the hypermycorrhizal phenotype of the B9 mutant is linked to its Pi-limited status favouring AM symbiosis in contrast to WT plants in Pi-replete conditions, and discuss the possible links between the altered response of the B9 mutant to Pi, mycorrhization and infection by A. euteiches.
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http://dx.doi.org/10.1111/pce.12370DOI Listing
January 2015

Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis.

Proc Natl Acad Sci U S A 2013 Dec 25;110(50):20117-22. Epub 2013 Nov 25.

Institut National de la Recherche Agronomique, Unité Mixte de Recherche 1136, Interactions Arbres/Microorganismes, Centre de Nancy, Université de Lorraine, 54280 Champenoux, France.

The mutualistic symbiosis involving Glomeromycota, a distinctive phylum of early diverging Fungi, is widely hypothesized to have promoted the evolution of land plants during the middle Paleozoic. These arbuscular mycorrhizal fungi (AMF) perform vital functions in the phosphorus cycle that are fundamental to sustainable crop plant productivity. The unusual biological features of AMF have long fascinated evolutionary biologists. The coenocytic hyphae host a community of hundreds of nuclei and reproduce clonally through large multinucleated spores. It has been suggested that the AMF maintain a stable assemblage of several different genomes during the life cycle, but this genomic organization has been questioned. Here we introduce the 153-Mb haploid genome of Rhizophagus irregularis and its repertoire of 28,232 genes. The observed low level of genome polymorphism (0.43 SNP per kb) is not consistent with the occurrence of multiple, highly diverged genomes. The expansion of mating-related genes suggests the existence of cryptic sex-related processes. A comparison of gene categories confirms that R. irregularis is close to the Mucoromycotina. The AMF obligate biotrophy is not explained by genome erosion or any related loss of metabolic complexity in central metabolism, but is marked by a lack of genes encoding plant cell wall-degrading enzymes and of genes involved in toxin and thiamine synthesis. A battery of mycorrhiza-induced secreted proteins is expressed in symbiotic tissues. The present comprehensive repertoire of R. irregularis genes provides a basis for future research on symbiosis-related mechanisms in Glomeromycota.
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http://dx.doi.org/10.1073/pnas.1313452110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3864322PMC
December 2013

Fungal genes related to calcium homeostasis and signalling are upregulated in symbiotic arbuscular mycorrhiza interactions.

Fungal Biol 2013 Jan 30;117(1):22-31. Epub 2012 Nov 30.

College of Life Science and Technology, State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China.

Fluctuations in intracellular calcium levels generate signalling events and regulate different cellular processes. Whilst the implication of Ca(2+) in plant responses during arbuscular mycorrhiza (AM) interactions is well documented, nothing is known about the regulation or role of this secondary messenger in the fungal symbiont. The spatio-temporal expression pattern of putatively Ca(2+)-related genes of Glomus intraradices BEG141 encoding five proteins involved in membrane transport and one nuclear protein kinase, was investigated during the AM symbiosis. Expression profiles related to successful colonization of host roots were observed in interactions of G. intraradices with roots of wild-type Medicago truncatula (line J5) compared to the mycorrhiza-defective mutant dmi3/Mtsym13. Symbiotic fungal activity was monitored using stearoyl-CoA desaturase and phosphate transporter genes. Laser microdissection based-mapping of fungal gene expression in mycorrhizal root tissues indicated that the Ca(2+)-related genes were differentially upregulated in arbuscules and/or in intercellular hyphae. The spatio-temporal variations in gene expression suggest that the encoded proteins may have different functions in fungal development or function during symbiosis development. Full-length cDNA obtained for two genes with interesting expression profiles confirmed a close similarity with an endoplasmic reticulum P-type ATPase and a Vcx1-like vacuolar Ca(2+) ion transporter functionally characterized in other fungi and involved in the regulation of cell calcium pools. Possible mechanisms are discussed in which Ca(2+)-related proteins G. intraradices BEG141 may play a role in mobilization and perception of the intracellular messenger by the AM fungus during symbiotic interactions with host roots.
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http://dx.doi.org/10.1016/j.funbio.2012.11.002DOI Listing
January 2013

Influence of arbuscular mycorrhizal colonisation on cadmium induced Medicago truncatula root isoflavonoid accumulation.

Plant Physiol Biochem 2012 Nov 5;60:233-9. Epub 2012 Sep 5.

UMR Agroécologie INRA 1347/Agrosup/Université de Bourgogne, Pôle Interactions Plantes Microorganismes, ERL 6300 CNRS, BP 86510, 21065 Dijon Cedex, France.

Cadmium is a serious environmental pollution threats to the planet. Its accumulation in plants affects many cellular functions, resulting in growth and development inhibition, whose mechanisms are not fully understood. However, some fungi forming arbuscular mycorrhizal symbiosis with the majority of plant species have the capacity to buffer the deleterious effect of this heavy metal. In the present work we investigated the capacity of Rhizophagus irregularis (syn. Glomus irregularis) to alleviate cadmium stress in Medicago truncatula. In spite of a reduction in all mycorrhizal parameters, plants colonized for 21 days by R. irregularis and treated by 2 mg kg⁻¹ cadmium displayed less growth inhibition in comparison to plants grown without cadmium. Cadmium strongly increased the accumulation of some isoflavonoids and their derivates: formononetin, malonylononin, medicarpin 3-O-β-(6'-malonylglucoside), medicarpin and coumestrol. Interestingly, in plants colonized by R. irregularis we noticed a strong reduction of the cadmium-induced accumulation of root isoflavonoids, a part for medicarpin and coumestrol. Moreover, transcripts of chalcone reductase, a protein that we reported previously as being down-regulated in R. irregularis-colonized M. truncatula roots, revealed a similar expression pattern with a strong increase in response to cadmium and a reduced expression in cadmium-treated mycorrhizal roots.
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http://dx.doi.org/10.1016/j.plaphy.2012.08.014DOI Listing
November 2012

The Medicago truncatula sucrose transporter family: characterization and implication of key members in carbon partitioning towards arbuscular mycorrhizal fungi.

Mol Plant 2012 Nov 28;5(6):1346-58. Epub 2012 Aug 28.

UMR INRA 1347, Agrosup, Université de Bourgogne, Agroécologie, Pôle Interactions Plantes Microorganismes ERL CNRS 6300, BP 86510, 21065 Dijon Cedex, France.

We identified de novo sucrose transporter (SUT) genes involved in long-distance transport of sucrose from photosynthetic source leaves towards sink organs in the model leguminous species Medicago truncatula. The identification and functional analysis of sugar transporters provide key information on mechanisms that underlie carbon partitioning in plant-microorganism interactions. In that way, full-length sequences of the M. truncatula SUT (MtSUT) family were retrieved and biochemical characterization of MtSUT members was performed by heterologous expression in yeast. The MtSUT family now comprises six genes which distribute among Dicotyledonous clades. MtSUT1-1 and MtSUT4-1 are key members in regard to their expression profiles in source leaves and sink roots and were characterized as functional H(+)/sucrose transporters. Physiological and molecular responses to phosphorus supply and inoculation by the arbuscular mycorrhizal fungus (AMF) Glomus intraradices was studied by gene expression and sugar quantification analyses. Sucrose represents the main sugar transport form in M. truncatula and the expression profiles of MtSUT1-1, MtSUT2, and MtSUT4-1 highlight a fine-tuning regulation for beneficial sugar fluxes towards the fungal symbiont. Taken together, these results suggest distinct functions for proteins from the SUT1, SUT2, and SUT4 clades in plant and in biotrophic interactions.
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http://dx.doi.org/10.1093/mp/sss079DOI Listing
November 2012

Local and systemic mycorrhiza-induced protection against the ectoparasitic nematode Xiphinema index involves priming of defence gene responses in grapevine.

J Exp Bot 2012 Jun 9;63(10):3657-72. Epub 2012 Mar 9.

UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, Dijon, France.

The ectoparasitic dagger nematode (Xiphinema index), vector of Grapevine fanleaf virus (GFLV), provokes gall formation and can cause severe damage to the root system of grapevines. Mycorrhiza formation by Glomus (syn. Rhizophagus) intraradices BEG141 reduced both gall formation on roots of the grapevine rootstock SO4 (Vitis berlandieri×V. riparia) and nematode number in the surrounding soil. Suppressive effects increased with time and were greater when the nematode was post-inoculated rather than co-inoculated with the arbuscular mycorrhizal (AM) fungus. Using a split-root system, decreased X. index development was shown in mycorrhizal and non-mycorrhizal parts of mycorrhizal root systems, indicating that both local and systemic induced bioprotection mechanisms were active against the ectoparasitic nematode. Expression analyses of ESTs (expressed sequence tags) generated in an SSH (subtractive suppressive hybridization) library, representing plant genes up-regulated during mycorrhiza-induced control of X. index, and of described grapevine defence genes showed activation of chitinase 1b, pathogenesis-related 10, glutathione S-transferase, stilbene synthase 1, 5-enolpyruvyl shikimate-3-phosphate synthase, and a heat shock proein 70-interacting protein in association with the observed local and/or systemic induced bioprotection against the nematode. Overall, the data suggest priming of grapevine defence responses by the AM fungus and transmission of a plant-mediated signal to non-mycorrhizal tissues. Grapevine gene responses during AM-induced local and systemic bioprotection against X. index point to biological processes that are related either to direct effects on the nematode or to protection against nematode-imposed stress to maintain root tissue integrity.
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http://dx.doi.org/10.1093/jxb/ers046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3388824PMC
June 2012

Arbuscular mycorrhizal fungi associated with Artemisia umbelliformis Lam, an endangered aromatic species in Southern French Alps, influence plant P and essential oil contents.

Mycorrhiza 2011 Aug 18;21(6):523-535. Epub 2011 Jan 18.

UMR INRA 1088/CNRS 5184/Université Bourgogne, Plante-Microbe-Environnement, INRA-CMSE, 17 rue Sully, BP 86510, 21065, Dijon Cedex, France.

Root colonization by arbuscular mycorrhizal (AM) fungi of Artemisia umbelliformis, investigated in natural and cultivated sites in the Southern Alps of France, showed typical structures (arbuscules, vesicles, hyphae) as well as spores and mycelia in its rhizosphere. Several native AM fungi belonging to different Glomeromycota genera were identified as colonizers of A. umbelliformis roots, including Glomus tenue, Glomus intraradices, G. claroideum/etunicatum and a new Acaulospora species. The use of the highly mycorrhizal species Trifolium pratense as a companion plant impacted positively on mycorrhizal colonization of A. umbelliformis under greenhouse conditions. The symbiotic performance of an alpine microbial community including native AM fungi used as inoculum on A. umbelliformis was evaluated in greenhouse conditions by comparison with mycorrhizal responses of two other alpine Artemisia species, Artemisia glacialis and Artemisia genipi Weber. Contrary to A. genipi Weber, both A. umbelliformis and A. glacialis showed a significant increase of P concentration in shoots. Volatile components were analyzed by GC-MS in shoots of A. umbelliformis 6 months after inoculation. The alpine microbial inoculum increased significantly the percentage of E-β-ocimene and reduced those of E-2-decenal and (E,E)-2-4-decadienal indicating an influence of alpine microbial inoculum on essential oil production. This work provides practical indications for the use of native AM fungi for A. umbelliformis field culture.
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http://dx.doi.org/10.1007/s00572-010-0354-yDOI Listing
August 2011

Arbuscular mycorrhizal symbiosis elicits proteome responses opposite of P-starvation in SO4 grapevine rootstock upon root colonisation with two Glomus species.

Mycorrhiza 2011 Aug 6;21(6):473-493. Epub 2011 Jan 6.

UMR INRA 1088, CNRS 5184, U. Bourgogne, PME, INRA, BP 86510, 21065, Dijon Cedex, France.

Although plant biotisation with arbuscular mycorrhizal fungi (AMF) is a promising strategy for improving plant health, a better knowledge regarding the molecular mechanisms involved is required. In this context, we sought to analyse the root proteome of grapevine rootstock Selection Oppenheim 4 (SO4) upon colonisation with two AMF. As expected, AMF colonisation stimulates plant biomass. At the proteome level, changes in protein amounts due to AMF colonisation resulted in 39 differentially accumulated two-dimensional electrophoresis spots in AMF roots relative to control. Out of them, 25 were co-identified in SO4 roots upon colonisation by Glomus irregulare and Glomus mosseae supporting the existence of conserved plant responses to AM symbiosis in a woody perennial species. Among the 18 proteins whose amount was reduced in AMF-colonised roots were proteins involved in glycolysis, protein synthesis and fate, defence and cell rescue, ethylene biosynthesis and purine and pyrimidine salvage degradation. The six co-identified proteins whose amount was increased had functions in energy production, signalling, protein synthesis and fate including proteases. Altogether these data confirmed that a part of the accommodation program of AMF previously characterized in annual plants is maintained within roots of the SO4 rootstock cuttings. Nonetheless, particular responses also occurred involving proteins of carbon metabolism, development and root architecture, defence and cell rescue, anthocyanin biosynthesis and P remobilization, previously reported as induced upon P-starvation. This suggests the occurrence of P reprioritization upon AMF colonization in a woody perennial plant species with agronomical interest.
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http://dx.doi.org/10.1007/s00572-010-0352-0DOI Listing
August 2011

Stimulation of defense reactions in Medicago truncatula by antagonistic lipopeptides from Paenibacillus sp. strain B2.

Appl Environ Microbiol 2010 Nov 24;76(22):7420-8. Epub 2010 Sep 24.

UMR INRA 1088, CNRS 5184, Université de Bourgogne Plante-Microbe-Environnement CMSE-INRA, 17 Rue Sully, BP 86510, 21065 Dijon Cedex, France.

With the aim of obtaining new strategies to control plant diseases, we investigated the ability of antagonistic lipopolypeptides (paenimyxin) from Paenibacillus sp. strain B2 to elicit hydrogen peroxide (H₂O₂) production and several defense-related genes in the model legume Medicago truncatula. For this purpose, M. truncatula cell suspensions were used and a pathosystem between M. truncatula and Fusarium acuminatum was established. In M. truncatula cell cultures, the induction of H₂O₂ reached a maximum 20 min after elicitation with paenimyxin, whereas concentrations higher than 20 μM inhibited H₂O₂ induction and this was correlated with a lethal effect. In plant roots incubated with different concentrations of paenimyxin for 24 h before inoculation with F. acuminatum, paenimyxin at a low concentration (ca. 1 μM) had a protective effect and suppressed 95% of the necrotic symptoms, whereas a concentration higher than 10 μM had an inhibitory effect on plant growth. Gene responses were quantified in M. truncatula by semiquantitative reverse transcription-PCR (RT-PCR). Genes involved in the biosynthesis of phytoalexins (phenylalanine ammonia-lyase, chalcone synthase, chalcone reductase), antifungal activity (pathogenesis-related proteins, chitinase), or cell wall (invertase) were highly upregulated in roots or cells after paenimyxin treatment. The mechanisms potentially involved in plant protection are discussed.
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http://dx.doi.org/10.1128/AEM.00171-10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2976201PMC
November 2010

Agroecology: the key role of arbuscular mycorrhizas in ecosystem services.

Mycorrhiza 2010 Nov 10;20(8):519-30. Epub 2010 Aug 10.

UMR INRA 1088/CNRS 5184/Université Bourgogne, Plante-Microbe-Environnement, INRA-CMSE, BP 86510, 21065, Dijon Cedex, France.

The beneficial effects of arbuscular mycorrhizal (AM) fungi on plant performance and soil health are essential for the sustainable management of agricultural ecosystems. Nevertheless, since the 'first green revolution', less attention has been given to beneficial soil microorganisms in general and to AM fungi in particular. Human society benefits from a multitude of resources and processes from natural and managed ecosystems, to which AM make a crucial contribution. These resources and processes, which are called ecosystem services, include products like food and processes like nutrient transfer. Many people have been under the illusion that these ecosystem services are free, invulnerable and infinitely available; taken for granted as public benefits, they lack a formal market and are traditionally absent from society's balance sheet. In 1997, a team of researchers from the USA, Argentina and the Netherlands put an average price tag of US $33 trillion a year on these fundamental ecosystem services. The present review highlights the key role that the AM symbiosis can play as an ecosystem service provider to guarantee plant productivity and quality in emerging systems of sustainable agriculture. The appropriate management of ecosystem services rendered by AM will impact on natural resource conservation and utilisation with an obvious net gain for human society.
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http://dx.doi.org/10.1007/s00572-010-0333-3DOI Listing
November 2010

Transcription of two blue copper-binding protein isogenes is highly correlated with arbuscular mycorrhizal development in Medicago truncatula.

Mol Plant Microbe Interact 2010 Sep;23(9):1175-83

UMR 1088 INRA/5184 CNRS/Université de Bourgogne, Plante-Microbe-Environnement, INRA-CMSE, Dijon BP 86510, 21065 Dijon Cedex, France.

Expression profiling of two paralogous arbuscular mycorrhizal (AM)-specific blue copper-binding gene (MtBcp1a and MtBcp1b) isoforms was performed by real-time quantitative polymerase chain reaction in wild-type Medicago truncatula Jemalong 5 (J5) during the mycorrhizal development with Glomus intraradices for up to 7 weeks. Time-course analysis in J5 showed that expression of both MtBcp1 genes increased continuously and correlated strongly with the colonization intensity and arbuscule content. MtPT4, selected as a reference gene of the functional plant-fungus association, showed a weaker correlation to mycorrhizal development. In a second experiment, a range of mycorrhizal mutants of the wild-type J5 was assessed. Strictly AM-penetration-defective TRV25-C and TRV25-D (dmi3, Mtsym13), hypomycorrhizal TR25 and TR89 (dmi2, Mtsym2) mutants, and a hypermycorrhizal mutant TRV17 (sunn, Mtsym12) were compared with J5 3 and 7 weeks after inoculation. No MtBcp1 transcripts were detected in the mutants blocked at the appressoria stage. Conversely, TR25, TR89, and J5 showed a gradual increase of the expression of both MtBcp1 genes in 3- and 7-week-old plants, similar to the increase in colonization intensity and arbuscule abundance. The strong correlation between the expression level of AM-specific blue copper-binding protein-encoding genes and AM colonization may imply a basic role in symbiotic functioning for these genes, which may serve as new molecular markers of arbuscule development in M. truncatula.
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http://dx.doi.org/10.1094/MPMI-23-9-1175DOI Listing
September 2010

Symbiosis-related pea genes modulate fungal and plant gene expression during the arbuscule stage of mycorrhiza with Glomus intraradices.

Mycorrhiza 2010 Aug 22;20(6):427-43. Epub 2010 Jan 22.

UMR 1088 INRA/5184 CNRS/Université de Bourgogne Plante-Microbe-Environnement, INRA-CMSE, 21065 Dijon Cedex, France.

The arbuscular mycorrhiza association results from a successful interaction between genomes of the plant and fungal symbiotic partners. In this study, we analyzed the effect of inactivation of late-stage symbiosis-related pea genes on symbiosis-associated fungal and plant molecular responses in order to gain insight into their role in the functional mycorrhizal association. The expression of a subset of ten fungal and eight plant genes, previously reported to be activated during mycorrhiza development, was compared in Glomus intraradices-inoculated wild-type and isogenic genotypes of pea mutated for the PsSym36, PsSym33, and PsSym40 genes where arbuscule formation is inhibited or fungal turnover modulated, respectively. Microdissection was used to corroborate arbuscule-related fungal gene expression. Molecular responses varied between pea genotypes and with fungal development. Most of the fungal genes were downregulated when arbuscule formation was defective, and several were upregulated with more rapid fungal development. Some of the plant genes were also affected by inactivation of the PsSym36, PsSym33, and PsSym40 loci, but in a more time-dependent way during root colonization by G. intraradices. Results indicate a role of the late-stage symbiosis-related pea genes not only in mycorrhiza development but also in the symbiotic functioning of arbuscule-containing cells.
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http://dx.doi.org/10.1007/s00572-009-0292-8DOI Listing
August 2010

Development and activity of Glomus intraradices as affected by co-existence with Glomus claroideum in one root system.

Mycorrhiza 2009 Aug 18;19(6):393-402. Epub 2009 Apr 18.

UMR 1088 INRA/5184 CNRS/Université de Bourgogne, Plante-Microbe-Environnement, BP 86510, 21065, Dijon Cedex, France.

The co-existence of two arbuscular mycorrhizal fungal (AMF) species, Glomus intraradices and Glomus claroideum, in the root systems of plants was investigated in a greenhouse experiment aimed at reconstructing interactions during an early stage of primary succession on a coal-mine spoil bank in Central Europe. Two plant species, Tripleurospermum inodorum and Calamagrostis epigejos, were inoculated either with one or both AMF species. Fungal development, determined by trypan blue and alkaline phosphatase staining as well as by PCR amplification of rRNA genes with species-specific primers, and the expression of five genes with different metabolic functions in the intraradical structures of G. intraradices were followed after 6 and 9 weeks of cultivation. The two AMF closely co-existed in the root systems of both plants possibly through similar colonisation rates and competitivity. Inoculation with the two fungi, however, did not bring any additional benefit to the host plants in comparison with single inoculation; moreover, plant growth depression observed after inoculation with G. claroideum persisted also in mixed inoculation. The expression of all the assayed G. intraradices genes was affected either by host plant or by co-inoculation with G. claroideum. The effects of both factors depended on the time of sampling, which underlines the importance of addressing this topic in time-course studies.
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http://dx.doi.org/10.1007/s00572-009-0243-4DOI Listing
August 2009

Symbiosis-related plant genes modulate molecular responses in an arbuscular mycorrhizal fungus during early root interactions.

Mol Plant Microbe Interact 2009 Mar;22(3):341-51

UMR 1088 INRA/5184 CNRS/Université de Bourgogne, Plante-Microbe-Environnement, INRA-CMSE, BP 86510, 21065 Dijon Cedex, France.

To gain further insight into the role of the plant genome in arbuscular mycorrhiza (AM) establishment, we investigated whether symbiosis-related plant genes affect fungal gene expression in germinating spores and at the appressoria stage of root interactions. Glomus intraradices genes were identified in expressed sequence tag libraries of mycorrhizal Medicago truncatula roots by in silico expression analyses. Transcripts of a subset of genes, with predicted functions in transcription, protein synthesis, primary or secondary metabolism, or of unknown function, were monitored in spores and germinating spores and during interactions with roots of wild-type or mycorrhiza-defective (Myc-) mutants of M. truncatula. Not all the fungal genes were active in quiescent spores but all were expressed when G. intraradices spores germinated in wild-type M. truncatula root exudates or when appressoria or arbuscules were formed in association with wild-type M. truncatula roots. Most of the fungal genes were upregulated or induced at the stage of appressorium development. Inactivation of the M. truncatula genes DMI1, DMI2/MtSYM2, or DMI3/MtSYM13 was associated with altered fungal gene expression (nonactivation or inhibition), modified appressorium structure, and plant cell wall responses, providing first evidence that cell processes modified by symbiosis-related plant genes impact on root interactions by directly modulating AM fungal activity.
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http://dx.doi.org/10.1094/MPMI-22-3-0341DOI Listing
March 2009

An STE12 gene identified in the mycorrhizal fungus Glomus intraradices restores infectivity of a hemibiotrophic plant pathogen.

New Phytol 2009 16;181(3):693-707. Epub 2008 Dec 16.

UMR INRA 1088/CNRS 5184/Université de Bourgogne, Plante-Microbe-Environnement, 17 Rue Sully - BP 86510 - 21065 Dijon Cedex, France.

Mechanisms of root penetration by arbuscular mycorrhizal (AM) fungi are unknown and investigations are hampered by the lack of transformation systems for these unculturable obligate biotrophs. Early steps of host infection by hemibiotrophic fungal phytopathogens, sharing common features with those of AM fungal colonization, depend on the transcription factor STE12. Using degenerated primers and rapid amplification of cDNA ends, we isolated the full-length cDNA of an STE12-like gene, GintSTE, from Glomus intraradices and profiled GintSTE expression by real-time and in situ RT-PCR. GintSTE activity and function were investigated by heterologous complementation of a yeast ste12Delta mutant and a Colletotrichum lindemuthianum clste12Delta mutant. * Sequence data indicate that GintSTE is similar to STE12 from hemibiotrophic plant pathogens, especially Colletotrichum spp. Introduction of GintSTE into a noninvasive mutant of C. lindemuthianum restored fungal infectivity of plant tissues. GintSTE expression was specifically localized in extraradicular fungal structures and was up-regulated when G. intraradices penetrated roots of wild-type Medicago truncatula as compared with an incompatible mutant. Results suggest a possible role for GintSTE in early steps of root penetration by AM fungi, and that pathogenic and symbiotic fungi may share common regulatory mechanisms for invasion of plant tissues.
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http://dx.doi.org/10.1111/j.1469-8137.2008.02696.xDOI Listing
March 2009

Preferential colonization of Solanum tuberosum L. roots by the fungus Glomus intraradices in arable soil of a potato farming area.

Appl Environ Microbiol 2008 Sep 1;74(18):5776-83. Epub 2008 Aug 1.

Dipartimento di Scienze dell'Ambiente e della Vita, Università del Piemonte Orientale Amedeo Avogadro, via Bellini 25/G, 15100 Alessandria, Italy.

The symbiosis between plant roots and arbuscular mycorrhizal (AM) fungi has been shown to affect both the diversity and productivity of agricultural communities. In this study, we characterized the AM fungal communities of Solanum tuberosum L. (potato) roots and of the bulk soil in two nearby areas of northern Italy, in order to verify if land use practices had selected any particular AM fungus with specificity to potato plants. The AM fungal large-subunit (LSU) rRNA genes were subjected to nested PCR, cloning, sequencing, and phylogenetic analyses. One hundred eighty-three LSU rRNA sequences were analyzed, and eight monophyletic ribotypes, belonging to Glomus groups A and B, were identified. AM fungal communities differed between bulk soil and potato roots, as one AM fungal ribotype, corresponding to Glomus intraradices, was much more frequent in potato roots than in soils (accounting for more than 90% of sequences from potato samples and less than 10% of sequences from soil samples). A semiquantitative heminested PCR with specific primers was used to confirm and quantify the AM fungal abundance observed by cloning. Overall results concerning the biodiversity of AM fungal communities in roots and in bulk soils from the two studied areas suggested that potato roots were preferentially colonized by one AM fungal species, G. intraradices.
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http://dx.doi.org/10.1128/AEM.00719-08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2547043PMC
September 2008

Impact of a new biopesticide produced by Paenibacillus sp. strain B2 on the genetic structure and density of soil bacterial communities.

Pest Manag Sci 2007 Mar;63(3):269-75

UMR INRA 1088/CNRS 5184/Université de Bourgogne, Plante-Microbe-Environnement CMSE-INRA, 17 rue Sully, BP 86510, 21065 Dijon Cedex, France.

The effect of paenimyxin, a new biopesticide produced by Paenibacillus sp. strain B2, on the density of soil bacterial communities was assessed by colony counting and by 16S rDNA and nirK quantitative polymerase chain reaction (PCR). Paenimyxin had a negative effect on the bacterial colony-forming unit (CFU) number, which was significantly reduced 2 and 4 days after treatment. The effect of paenimyxin on cultivatable bacteria was negligible 7 days after treatment. Approximately 10(7) 16S rDNA sequences per gram of soil (dry weight) were detected by quantitative PCR in all samples. Paenimyxin did not affect the quantification of 16S rDNA or of the denitrifying bacterial community. In addition, RISA fingerprinting showed that the genetic structure of the bacterial communities was significantly modified 2 days after paenimyxin application at 50 microM and 4 days after treatment at lower concentrations (0.5 and 5 microM). The impact of paenimyxin treatment on the genetic structure of soil bacterial communities was transient, as no effect could be observed after 7, 14 and 28 days when compared with the untreated control.
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http://dx.doi.org/10.1002/ps.1335DOI Listing
March 2007

Repetitive DNA sequences include retrotransposons in genomes of the Glomeromycota.

Genetica 2006 Sep-Nov;128(1-3):455-69

UMR 1088 INRA/5184 CNRS/Université de Bourgogne Plante-Microbe-Environnement, INRA-CMSE, BP 86510, 21065 Dijon Cedex, France.

Twenty-five repetitive elements are first described in the genomes of the arbuscular mycorrhizal (AM) fungi Gigaspora margarita, Gig. rosea and Glomus mosseae. Nineteen repetitive DNA sequences isolated by genomic library screening and four by self-priming PCR had no homology to known DNA sequences, except for two Gig. margarita sequences and one Gig. rosea sequence which showed amino acid similarity to retrotransposons. Part of the Gig. rosea sequence was also similar to a DNA transposon. Two other retrotransposon sequences were isolated using PCR targeting of reverse transcriptase and ribonuclease H domains. Evidence is provided for three gypsy-like LTR retrotransposon and two non-LTR retrotransposon sequences in the AM fungal genomes. Four contain stop codons indicating that they cannot be active. Expression of three retrotransposons was not detected in germinating spores or intraradical hyphae of Gig. margarita. Southern blot analyses indicated that these three sequences are dispersed in the genome and that two are methylated. Sequence analysis of different GmarLTR1 copies showed they have undergone mutations by transitions, which may have been induced by cytosine methylation. Transposable elements may have played a major role in shaping genome structure and size during evolution of the Glomeromycota.
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http://dx.doi.org/10.1007/s10709-006-0019-0DOI Listing
January 2007

Molecular changes in Pisum sativum L. roots during arbuscular mycorrhiza buffering of cadmium stress.

Mycorrhiza 2005 Dec 11;16(1):51-60. Epub 2005 Nov 11.

UMR 1088 INRA/5184 CNRS/U., Bourgogne Plante-Microbe-Environnement, INRA-CMSE, BP 86510, 21065, Dijon Cédex, France.

Molecular responses to cadmium (Cd) stress were studied in mycorrhizal and non-mycorrhizal Pisum sativum L. cv. Frisson inoculated with Glomus intraradices. Biomass decreases caused by the heavy metal were significantly less in mycorrhizal than in non-mycorrhizal plants. Real-time reverse transcriptase-polymerase chain reaction showed that genes implicated in pathways of Cd detoxification varied in response to mycorrhiza development or Cd application. Expression of a metallothionein-encoding gene increased strongly in roots of Cd-treated non-mycorrhizal plants. Genes encoding gamma-glutamylcysteine synthetase and glutathione (GSH) synthetase, responsible for the synthesis of the phytochelatin (PC) precursor GSH, were activated by Cd in mycorrhizal and non-mycorrhizal plants. Cd stress decreased accumulation of GSH/homoglutathione (hGSH) and increased thiol groups in pea roots, whether mycorrhizal or not, suggesting synthesis of PCs and/or homophytochelatins. An hGSH synthetase gene, involved in hGSH synthesis, did not respond to Cd alone but was activated by mycorrhizal development in the presence of Cd. Transcript levels of a glutathione reductase gene were only increased in non-mycorrhizal roots treated with Cd. Studies of three stress-related genes showed that a heat-shock protein gene was activated in mycorrhizal roots or by Cd and chitinase gene transcripts increased under Cd stress to a greater extent in mycorrhizal roots, whilst a chalcone isomerase gene was only up-regulated by Cd. Results indicate that although heavy metal chelation pathways contribute to Cd stress responses in pea, they may not make a major contribution to Cd tolerance strategies operating in the arbuscular mycorrhizal symbiosis.
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http://dx.doi.org/10.1007/s00572-005-0016-7DOI Listing
December 2005

Construction and validation of cDNA-based Mt6k-RIT macro- and microarrays to explore root endosymbioses in the model legume Medicago truncatula.

J Biotechnol 2004 Mar;108(2):95-113

Lehrstuhl für Genetik, Fakultät für Biologie, Universität Bielefeld, Postfach 100131, Bielefeld D-33501, Germany.

To construct macro- and microarray tools suitable for expression profiling in root endosymbioses of the model legume Medicago truncatula, we PCR-amplified a total of 6048 cDNA probes representing genes expressed in uninfected roots, mycorrhizal roots and young root nodules [Nucleic Acids Res. 30 (2002) 5579]. Including additional probes for either tissue-specific or constitutively expressed control genes, 5651 successfully amplified gene-specific probes were used to grid macro- and to spot microarrays designated Mt6k-RIT (M. truncatula 6k root interaction transcriptome). Subsequent to a technical validation of microarray printing, we performed two pilot expression profiling experiments using Cy-labeled targets from Sinorhizobium meliloti-induced root nodules and Glomus intraradices-colonized arbuscular mycorrhizal roots. These targets detected marker genes for nodule and arbuscular mycorrhiza development, amongst them different nodule-specific leghemoglobin and nodulin genes as well as a mycorrhiza-specific phosphate transporter gene. In addition, we identified several dozens of genes that have so far not been reported to be differentially expressed in nodules or arbuscular mycorrhiza thus demonstrating that Mt6k-RIT arrays serve as useful tools for an identification of genes relevant for legume root endosymbioses. A comprehensive profiling of such candidate genes will be very helpful to the development of breeding strategies and for the improvement of cultivation management targeted at increasing legume use in sustainable agricultural systems.
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http://dx.doi.org/10.1016/j.jbiotec.2003.11.011DOI Listing
March 2004

Diversity of arbuscular mycorrhizal fungi colonising roots of the grass species Agrostis capillaris and Lolium perenne in a field experiment.

Mycorrhiza 2004 Apr 24;14(2):111-7. Epub 2003 May 24.

Scottish Agricultural College, Crop Science Department, West Mains Road, Edinburgh EH9 3JG, UK.

Analysis of arbuscular mycorrhizal (AM) fungal diversity through morphological characters of spores and intraradicular hyphae has suggested previously that preferential associations occur between plants and AM fungi. A field experiment was established to investigate whether AM fungal diversity is affected by different host plants in upland grasslands. Indigenous vegetation from plots in an unimproved pasture was replaced with monocultures of either Agrostis capillaris or Lolium perenne. Modification of the diversity of AM fungi in these plots was evaluated by analysis of partial sequences in the large subunit (LSU) ribosomal RNA (rDNA) genes. General primers for AM fungi were designed for the PCR amplification of partial sequences using DNA extracted from root tissues of A. capillaris and L. perenne. PCR products were used to construct LSU rDNA libraries. Sequencing of randomly selected clones indicated that plant roots were colonised by AM fungi belonging to the genera Glomus, Acaulospora and Scutellospora. There was a difference in the diversity of AM fungi colonising roots of A. capillaris and L. perenne that was confirmed by PCR using primers specific for each sequence group. These molecular data suggest the existence of a selection pressure of plants on AM fungal communities.
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http://dx.doi.org/10.1007/s00572-003-0244-7DOI Listing
April 2004

Exploring root symbiotic programs in the model legume Medicago truncatula using EST analysis.

Nucleic Acids Res 2002 Dec;30(24):5579-92

Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, CNRS-INRA, Laboratoire de Biométrie et Intelligence Artificielle, INRA, 31326 Castanet-Tolosan Cedex, France.

We report on a large-scale expressed sequence tag (EST) sequencing and analysis program aimed at characterizing the sets of genes expressed in roots of the model legume Medicago truncatula during interactions with either of two microsymbionts, the nitrogen-fixing bacterium Sinorhizobium meliloti or the arbuscular mycorrhizal fungus Glomus intraradices. We have designed specific tools for in silico analysis of EST data, in relation to chimeric cDNA detection, EST clustering, encoded protein prediction, and detection of differential expression. Our 21 473 5'- and 3'-ESTs could be grouped into 6359 EST clusters, corresponding to distinct virtual genes, along with 52 498 other M.truncatula ESTs available in the dbEST (NCBI) database that were recruited in the process. These clusters were manually annotated, using a specifically developed annotation interface. Analysis of EST cluster distribution in various M.truncatula cDNA libraries, supported by a refined R test to evaluate statistical significance and by 'electronic northern' representation, enabled us to identify a large number of novel genes predicted to be up- or down-regulated during either symbiotic root interaction. These in silico analyses provide a first global view of the genetic programs for root symbioses in M.truncatula. A searchable database has been built and can be accessed through a public interface.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC140066PMC
http://dx.doi.org/10.1093/nar/gkf685DOI Listing
December 2002
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