Publications by authors named "Vivienne Gianinazzi-Pearson"

34 Publications

Life's rich tapestry : A tribute to Sally E. Smith (1941-2019).

Mycorrhiza 2020 Jan;30(1):1-3

SACCA SARL, 7 rue Bernard Courtois, 21000, Dijon, France.

With the recent passing away of Emeritus Professor Sally (Sarah) E. Smith, the mycorrhiza research community has lost one of its most outstanding members. Sally's contribution to knowledge in the fields of soil microbiology and root physiology will continue to be an inspiration to present and future scientists.
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http://dx.doi.org/10.1007/s00572-020-00936-0DOI Listing
January 2020

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

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

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 symbiosis elicits shoot proteome changes that are modified during cadmium stress alleviation in Medicago truncatula.

BMC Plant Biol 2011 May 5;11:75. Epub 2011 May 5.

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

Background: Arbuscular mycorrhizal (AM) fungi, which engage a mutualistic symbiosis with the roots of most plant species, have received much attention for their ability to alleviate heavy metal stress in plants, including cadmium (Cd). While the molecular bases of Cd tolerance displayed by mycorrhizal plants have been extensively analysed in roots, very little is known regarding the mechanisms by which legume aboveground organs can escape metal toxicity upon AM symbiosis. As a model system to address this question, we used Glomus irregulare-colonised Medicago truncatula plants, which were previously shown to accumulate and tolerate heavy metal in their shoots when grown in a substrate spiked with 2 mg Cd kg(-1).

Results: The measurement of three indicators for metal phytoextraction showed that shoots of mycorrhizal M. truncatula plants have a capacity for extracting Cd that is not related to an increase in root-to-shoot translocation rate, but to a high level of allocation plasticity. When analysing the photosynthetic performance in metal-treated mycorrhizal plants relative to those only Cd-supplied, it turned out that the presence of G. irregulare partially alleviated the negative effects of Cd on photosynthesis. To test the mechanisms by which shoots of Cd-treated mycorrhizal plants avoid metal toxicity, we performed a 2-DE/MALDI/TOF-based comparative proteomic analysis of the M. truncatula shoot responses upon mycorrhization and Cd exposure. Whereas the metal-responsive shoot proteins currently identified in non-mycorrhizal M. truncatula indicated that Cd impaired CO2 assimilation, the mycorrhiza-responsive shoot proteome was characterised by an increase in photosynthesis-related proteins coupled to a reduction in glugoneogenesis/glycolysis and antioxidant processes. By contrast, Cd was found to trigger the opposite response coupled the up-accumulation of molecular chaperones in shoot of mycorrhizal plants relative to those metal-free.

Conclusion: Besides drawing a first picture of shoot proteome modifications upon AM symbiosis and/or heavy metal stress in legume plants, the current work argues for allocation plasticity as the main driving force for Cd extraction in aboveground tissues of M. truncatula upon mycorrhization. Additionally, according to the retrieved proteomic data, we propose that shoots of mycorrhizal legume plants escape Cd toxicity through a metabolic shift implying the glycolysis-mediated mobilization of defence mechanisms at the expense of the photosynthesis-dependent symbiotic sucrose sink.
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http://dx.doi.org/10.1186/1471-2229-11-75DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3112074PMC
May 2011

Expression profiling of fungal genes during arbuscular mycorrhiza symbiosis establishment using direct fluorescent in situ RT-PCR.

Methods Mol Biol 2010 ;638:137-52

UMR INRA/CNRS /Université Bourgogne Plante-Microbe-Environnement, Dijon Cedex, France.

Expression profiling of fungal genes in the arbuscular mycorrhiza (AM) symbiosis has been based on studies of RNA extracted from fungal tissue or mycorrhizal roots, giving only a general picture of overall transcript levels in the targeted tissues. Information about the spatial distribution of transcripts within AM fungal structures during different developmental stages is essential to a better understanding of fungal activity in symbiotic interactions with host roots and to determine molecular events involved in establishment and functioning of the AM symbiosis. The obligate biotrophic nature of AM fungi is a challenge for developing new molecular methods to identify and localize their activity in situ. The direct fluorescent in situ (DIFIS) RT-PCR procedure described here represents a novel tool for spatial mapping of AM fungal gene expression simultaneously prior to root penetration, within fungal tissues in the host root and in the extraradical stage of fungal development.In order to enhance detection sensitivity of the in situ RT-PCR technique and enable localization of low abundance mRNA, we have adopted direct fluorescent labeling of primers for the amplification step to overcome the problem of low detection associated with digoxigenin or biotin-labeled primers and to avoid the multiplicity of steps associated with immunological detection. Signal detection has also been greatly improved by eliminating autofluorescence of AM fungal and root tissues using confocal microscopy.
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http://dx.doi.org/10.1007/978-1-60761-611-5_10DOI Listing
June 2010

Identification of in planta-expressed arbuscular mycorrhizal fungal proteins upon comparison of the root proteomes of Medicago truncatula colonised with two Glomus species.

Fungal Genet Biol 2010 Jul 11;47(7):608-18. Epub 2010 Mar 11.

UMR 1088 INRA/CNRS 5184/UB Plante-Microbe-Environnement, INRA-CMSE, BP86510, 21065 Dijon Cedex, France.

In the absence of sequenced genomes for arbuscular mycorrhizal (AM) fungi, their obligatory biotrophy makes their intra-radical biology especially recalcitrant to functional analyses. Because tandem mass spectrometry-based proteomics enables fungal gene product identifications in phyla lacking genomic information, we have compared as a way to enlarge the coverage of in planta expressed-mycorrhiza-related proteins, the root proteome responses of Medicago truncatula upon colonisation with two AM fungi, Glomus mosseae and G. intraradices, using two-dimensional electrophoresis. In contrast to phosphate fertilization, mycorrhization led to specific changes in the abundance of 99 spots, including 42 overlapping modifications between G. mosseae- and G. intraradices-colonised roots. The 32 confident identifications that could be retrieved following tandem mass spectrometry encompassed 21 fungal proteins whose homology-inferred functions were found to complement the working models so far proposed for the intra-radical functioning of AM fungi with regard to carbon utilization, energy generation, redox homeostasis and protein turnover-related processes.
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http://dx.doi.org/10.1016/j.fgb.2010.03.003DOI Listing
July 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

A Medicago truncatula mutant hyper-responsive to mycorrhiza and defective for nodulation.

Mycorrhiza 2009 Aug 4;19(6):435-441. Epub 2009 Apr 4.

UMR Génétique et Ecophysiologie des Légumineuses à Graines, INRA, BP 86510, 21065, Dijon Cedex, France.

One key strategy for the identification of plant genes required for mycorrhizal development is the use of plant mutants affected in mycorrhizal colonisation. In this paper, we report a new Medicago truncatula mutant defective for nodulation but hypermycorrhizal for symbiosis development and response. This mutant, called B9, presents a poor shoot and, especially, root development with short laterals. Inoculation with Glomus intraradices results in significantly higher root colonisation of the mutant than the wild-type genotype A17 (+20% for total root length, +16% for arbuscule frequency in the colonised part of the root, +39% for arbuscule frequency in the total root system). Mycorrhizal effects on shoot and root biomass of B9 plants are about twofold greater than in the wild-type genotype. The B9 mutant of M. truncatula is characterised by considerably higher root concentrations of the phytoestrogen coumestrol and by the novel synthesis of the coumestrol conjugate malonyl glycoside, absent from roots of wild-type plants. In conclusion, this is the first time that a hypermycorrhizal plant mutant affected negatively for nodulation (Myc(++), Nod (-/+) phenotype) is reported. This mutant represents a new tool for the study of plant genes differentially regulating mycorrhiza and nodulation symbioses, in particular, those related to autoregulation mechanisms.
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http://dx.doi.org/10.1007/s00572-009-0242-5DOI 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

From the editors.

Mycorrhiza 2009 Mar;19(3):219

, 625 SE 14th Court, Gresham, OR, 97080, USA.

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http://dx.doi.org/10.1007/s00572-008-0226-xDOI 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

Fungal proteins in the extra-radical phase of arbuscular mycorrhiza: a shotgun proteomic picture.

New Phytol 2009 Jan;181(2):248-260

Unité Mixte de Recherche Plante-Microbe-Environnement INRA 1088/CNRS 5184/Université de Bourgogne. INRA-CMSE. BP 86510. 21065 Dijon Cedex, France;Unité de Recherche 1268 Biopolymères- Interactions-Assemblages, Spectrométrie de Masse, INRA, rue de la Géraudière. BP 71627, 44316 Nantes Cedex 3, France.

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http://dx.doi.org/10.1111/j.1469-8137.2008.02659.xDOI Listing
January 2009

Mycorrhiza 2009.

Mycorrhiza 2009 Feb;19(2):67

, 625 SE 14th Court, Gresham, OR, 97080, USA.

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http://dx.doi.org/10.1007/s00572-008-0214-1DOI Listing
February 2009

On the mechanisms of cadmium stress alleviation in Medicago truncatula by arbuscular mycorrhizal symbiosis: a root proteomic study.

Proteomics 2009 Jan;9(2):420-33

UMR 1088 INRA/CNRS 5184/UB Plante-Microbe-Environnement, INRA-CMSE, Dijon, France.

The arbuscular mycorrhizal (AM) symbiosis belongs to the strategies plants have developed to cope with adverse environmental conditions including contamination by heavy metals such as cadmium (Cd). In the present work, we report on the protective effect conferred by AM symbiosis to the model legume Medicago truncatula grown in presence of Cd, and on the 2-D-based proteomic approach further used to compare the proteomes of M. truncatula roots either colonised or not with the AM fungus Glomus intraradices in Cd-free and Cd-contaminated substrates. The results indicated that at the proteome level, 9 out of the 15 cadmium-induced changes in nonmycorrhizal roots were absent or inverse in those Cd-treated and colonized by G. intraradices, including the G. intraradices-dependent down-accumulation of Cd stress-responsive proteins. Out of the twenty-six mycorrhiza-related proteins that were identified, only six displayed changes in abundance upon Cd exposure, suggesting that part of the symbiotic program, which displays low sensitivity to Cd, may be recruited to counteract Cd toxicity through the mycorrhiza-dependent synthesis of proteins having functions putatively involved in alleviating oxidative damages, including a cyclophilin, a guanine nucleotide-binding protein, an ubiquitin carboxyl-terminal hydrolase, a thiazole biosynthetic enzyme, an annexin, a glutathione S-transferase (GST)-like protein, and a S-adenosylmethionine (SAM) synthase.
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http://dx.doi.org/10.1002/pmic.200800336DOI Listing
January 2009

Effect of 2,4-diacetylphloroglucinol on pythium: cellular responses and variation in sensitivity among propagules and species.

Phytopathology 2003 Aug;93(8):966-75

ABSTRACT The antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) plays an important role in the suppression of plant pathogens by several strains of Pseudomonas spp. Based on the results of this study, there is variation within and among Pythium spp. to 2,4-DAPG. Also, various propagules of Pythium ultimum var. sporangiiferum, that are part of the asexual stage of the life cycle, differ considerably in their sensitivity to 2,4-DAPG. Mycelium was the most resistant structure, followed by zoosporangia, zoospore cysts, and zoospores. Additionally, we report for the first time that pH has a significant effect on the activity of 2,4-DAPG, with a higher activity at low pH. Furthermore, the level of acetylation of phloroglucinols is also a major determinant of their activity. Transmission electron microscopy studies revealed that 2,4-DAPG causes different stages of disorganization in hyphal tips of Pythium ultimum var. sporangiiferum, including alteration (proliferation, retraction, and disruption) of the plasma membrane, vacuolization, and cell content disintegration. The implications of these results for the efficacy and consistency of biological control of plant-pathogenic Pythium spp. by 2,4-DAPG-producing Pseudomonas spp. are discussed.
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http://dx.doi.org/10.1094/PHYTO.2003.93.8.966DOI Listing
August 2003

Spatial monitoring of gene activity in extraradical and intraradical developmental stages of arbuscular mycorrhizal fungi by direct fluorescent in situ RT-PCR.

Fungal Genet Biol 2008 Aug 11;45(8):1155-65. Epub 2008 May 11.

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

Gene expression profiling based on tissue extracts gives only limited information about genes associated with complex developmental processes such as those implicated in fungal interactions with plant roots during arbuscular mycorrhiza development and function. To overcome this drawback, a direct fluorescent in situ RT-PCR methodology was developed for spatial mapping of gene expression in different presymbiotic and symbiotic structures of an arbuscular mycorrhizal fungus. Transcript detection was optimized by targeting the LSU rRNA gene of Glomus intraradices and monitoring expression of a stearoyl-CoA-desaturase gene that is consistently expressed at high levels in spores, hyphae, arbuscules and vesicles. This method was further validated by localizing expression of fungal peptidylprolyl isomerase and superoxide dismutase genes, which are expressed to different extents in fungal structures. Direct fluorescent in situ RT-PCR offers new perspectives for the sensitive analysis of fungal developmental processes that occur during functional differentiation in symbiotic arbuscular mycorrhiza interactions.
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http://dx.doi.org/10.1016/j.fgb.2008.04.013DOI Listing
August 2008

Cadmium effects on populations of root nuclei in two pea genotypes inoculated or not with the arbuscular mycorrhizal fungus Glomus mosseae.

Mycorrhiza 2007 Mar 16;17(2):111-120. Epub 2006 Nov 16.

Department of Environmental and Life Science, University of Piemonte Orientale 'Amedeo Avogadro', Via Bellini 25G, 15100, Alessandria, Italy.

Plants possess a broad range of strategies to cope with cadmium (Cd) stress, including the arbuscular mycorrhizal (AM) symbiosis. In cell responses towards Cd, the contribution of changes in ploidy levels is still unclear. We used flow cytometry to investigate if nuclear ploidy changes are involved in response mechanisms toward Cd and to analyze the effect of the symbiotic status on populations of nuclei. The impact of Cd was investigated in roots of two pea (Pisum sativum L.) genotypes differing in their Cd-sensitivity (Cd-sensitive VIR4788 and Cd-tolerant VIR7128). In pea seedlings grown under hydropony, 25 and 250 microM Cd concentrations lead to an increase in 4 C together with a decrease in 2 C nuclei. The same genotypes, grown in soil/sand substrate, were inoculated or not with the AM fungus Glomus mosseae BEG12 and treated or not with Cd at transplanting (Cd1) or 2 weeks after (Cd2). The Cd2 increased the proportion of 6 and 8 C nuclei in the mycorrhizal VIR4788 and in the non-mycorrhizal VIR7128 genotypes. Thus, changes in ploidy levels reflect pea responses towards Cd, which are modulated by the symbiotic interaction. The Cd-induced increase in ploidy may account for changes in DNA transcription and/or translation.
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http://dx.doi.org/10.1007/s00572-006-0082-5DOI Listing
March 2007

Cooccurring plants forming distinct arbuscular mycorrhizal morphologies harbor similar AM fungal species.

Mycorrhiza 2006 Dec 15;17(1):37-49. Epub 2006 Nov 15.

Soil Science Laboratory, Faculty of Agriculture, Niigata University, 8050, Ikarashi-2, Niigata, 950-2181, Japan.

Arbuscular mycorrhizal (AM) fungal spores were isolated from field transplants and rhizosphere soil of Hedera rhombea (Miq) Bean and Rubus parvifolius L., which form Paris-type and Arum-type AM, respectively. DNA from the spore isolates was used to generate molecular markers based on partial large subunit (LSU) ribosomal RNA (rDNA) sequences to determine AM fungi colonizing field-collected roots of the two plant species. Species that were isolated as spores and identified morphologically and molecularly were Gigaspora rosea and Scutellospora erythropa from H. rhombea, Acaulospora longula and Glomus etunicatum from R. parvifolius, and Glomus claroideum from both plants. The composition of the AM fungal communities with respect to plant trap cultures was highly divergent between plant species. Analysis of partial LSU rDNA sequences amplified from field-collected roots of the two plant species with PCR primers designed for the AM fungi indicated that both plants were colonized by G. claroideum, G. etunicatum, A. longula, and S. erythropa. G. rosea was not detected in the field-collected roots of either plant species. Four other AM fungal genotypes, which were not isolated as spores in trap cultures from the two plant species, were also found in the roots of both plant species; two were closely related to Glomus intraradices and Glomus clarum. One genotype, which was most closely related to Glomus microaggregatum, was confined to R. parvifolius, whereas an uncultured Glomeromycotan fungus occurred only in roots of H. rhombea. S. erythropa was the most dominant fungus found in the roots of H. rhombea. The detection of the same AM fungal species in field-collected roots of H. rhombea and R. parvifolius, which form Paris- and Arum-type AM, respectively, shows that AM morphology in these plants is strongly influenced by the host plant genotypes as appears to be the case in many plant species in natural ecosystems, although there are preferential associations between the hosts and colonizing AM fungi in this study.
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http://dx.doi.org/10.1007/s00572-006-0079-0DOI Listing
December 2006

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

Pseudomonas fluorescens and Glomus mosseae trigger DMI3-dependent activation of genes related to a signal transduction pathway in roots of Medicago truncatula.

Plant Physiol 2005 Oct 23;139(2):1065-77. Epub 2005 Sep 23.

Unité Mixte de Recherche, Institut National de la Recherche Agronomique 1088/Centre National de la Recherche Scientifique 5184/Université de Bourgogne Plante-Microbe-Environnement, Dijon, France.

Plant genes induced during early root colonization of Medicago truncatula Gaertn. J5 by a growth-promoting strain of Pseudomonas fluorescens (C7R12) have been identified by suppressive subtractive hybridization. Ten M. truncatula genes, coding proteins associated with a putative signal transduction pathway, showed an early and transient activation during initial interactions between M. truncatula and P. fluorescens, up to 8 d after root inoculation. Gene expression was not significantly enhanced, except for one gene, in P. fluorescens-inoculated roots of a Myc(-)Nod(-) genotype (TRV25) of M. truncatula mutated for the DMI3 (syn. MtSYM13) gene. This gene codes a Ca(2+) and calmodulin-dependent protein kinase, indicating a possible role of calcium in the cellular interactions between M. truncatula and P. fluorescens. When expression of the 10 plant genes was compared in early stages of root colonization by mycorrhizal and rhizobial microsymbionts, Glomus mosseae activated all 10 genes, whereas Sinorhizobium meliloti only activated one and inhibited four others. None of the genes responded to inoculation by either microsymbiont in roots of the TRV25 mutant. The similar response of the M. truncatula genes to P. fluorescens and G. mosseae points to common molecular pathways in the perception of the microbial signals by plant roots.
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http://dx.doi.org/10.1104/pp.105.067603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1256018PMC
October 2005

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

Identification of mycorrhiza-regulated genes with arbuscule development-related expression profile.

Plant Mol Biol 2004 Jul;55(4):553-66

Max-Planck Institut für terrestrische Mikrobiologie, and Laboratorium für Mikrobiologie, Philipps-University, Karl-von-Frisch-Strasse, Marburg, Germany.

Suppressive subtractive hybridisation was applied to the analysis of late stage arbuscular mycorrhizal development in pea. 96 cDNA clones were amplified and 81, which carried fragments more than 200 nt in size, were sequence analysed. Among 67 unique fragments, 10 showed no homology and 10 were similar to sequences with unknown function. RNA accumulation of the corresponding 67 genes was analysed by hybridisation of macro-arrays. The cDNAs used as probes were derived from roots of wild type and late mutant pea genotypes, inoculated or not with the AM fungus Glomus mosseae. After calibration, a more than 2.5-fold mycorrhiza-induced RNA accumulation was detected in two independent experiments in the wild type for 25 genes, 22 of which seemed to be induced specifically during late stage AM development. Differential expression for 7 genes was confirmed by RT-PCR using RNA from mycorrhiza and from controls of a different pea cultivar. In order to confirm arbuscule-related expression, the Medicago truncatula EST data base was screened for homologous sequences with putative mycorrhiza-related expression and among a number of sequences with significant similarities, a family of trypsin inhibitor genes could be identified. Mycorrhiza-induced RNA accumulation was verified for five members by real-time PCR and arbuscule-related activation of the promoter could be shown in transgenic roots for one of the genes, MtTi 1.
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http://dx.doi.org/10.1007/s11103-004-1303-yDOI Listing
July 2004

Fungal elicitation of signal transduction-related plant genes precedes mycorrhiza establishment and requires the dmi3 gene in Medicago truncatula.

Mol Plant Microbe Interact 2004 Dec;17(12):1385-93

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

Suppressive subtractive hybridization and expressed sequence tag sequencing identified 29 plant genes which are upregulated during the appressorium stage of mycorrhiza establishment between Medicago truncatula J5 (Myc+) and Glomus mosseae. Eleven genes coding plant proteins with predicted functions in signal transduction, transcription, and translation were investigated in more detail for their relation to early events of symbiotic interactions. Expression profiling showed that the genes are activated not only from the appressorium stage up to the fully established symbiosis in the Myc+ genotype of M. truncatula, but also when the symbionts are not in direct cell contact, suggesting that diffusible fungal molecules (Myc factors) play a, role in the induction of a signal-transduction pathway. Transcript accumulation in roots of a mycorrhiza-defective Myc- dmi3 mutant of M. truncatula is not modified by appressorium formation or diffusible fungal molecules, indicating that the signal transduction pathway is required for a successful G. mosseae-M. truncatula interaction leading to symbiosis development. The symbiotic nodulating bacterium Sinorhizobium meliloti does not activate the 11 genes, which supposes early discrimination by plant roots between the microbial symbionts.
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http://dx.doi.org/10.1094/MPMI.2004.17.12.1385DOI Listing
December 2004

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

A technical trick for studying proteomics in parallel to transcriptomics in symbiotic root-fungus interactions.

Proteomics 2004 Feb;4(2):451-3

UMR 1088 INRA/CNRS 5184/U, Bourgogne (Plante-Microbe- Environnement) INRA-CMSE, Dijon, France.

We have developed a protocol in which proteins and mRNA can be analyzed from single root samples. This experimental design was validated in arbuscular mycorrhiza by comparing the proteins profiles obtained with those from a classical protein extraction process. It is a step forward to make simultaneous proteome and transcriptiome profiling possible.
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http://dx.doi.org/10.1002/pmic.200300627DOI Listing
February 2004

Targeted proteomics to identify cadmium-induced protein modifications in Glomus mosseae-inoculated pea roots.

New Phytol 2003 Mar;157(3):555-567

UMR 1088 BBCE-IPM, INRA-CMSE, BP 86510, 21065 Dijon Cedex, France.

•   Arbuscular mycorrhiza (AM) can increase plant tolerance to heavy metals. A targeted proteomic approach was used to determine the putative identity of some of the proteins induced/modulated by cadmium (Cd) and to analyse the impact of the mycorrhizal process. •   The effect of Cd (100 mg Cd kg  substrate) applied either at planting or 15 d later on two pea (Pisum sativum) genotypes, differing in sensitivity to Cd inoculated or not with the AM fungus Glomus mosseae, was studied at three levels: plant biomass production, development of G. mosseae and root differential protein display with one- and two-dimensional gel electrophoresis (1-DE and 2-DE) analyses. •   Cd-induced growth inhibition was significantly alleviated by mycorrhiza in the Cd-sensitive genotype. The AM symbiosis modulated the expression of several proteins, identified by liquid chromatography-tandem mass spectrometry, newly induced and upregulated or downregulated by Cd. •   The protective effect of AM symbiosis towards Cd stress was observed in the Cd-sensitive genotype. Our results demonstrate the usefulness of proteomics to better understand the possible role of AM symbiosis in detoxification/response mechanisms towards Cd in pea plants.
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http://dx.doi.org/10.1046/j.1469-8137.2003.00682.xDOI Listing
March 2003

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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