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Systematic Analysis of Zn2Cys6 Transcription Factors Required for Development and Pathogenicity by High-Throughput Gene Knockout in the Rice Blast Fungus

Systematic Analysis of Zn2Cys6 Transcription Factors Required for Development and Pathogenicity by High-Throughput Gene Knockout in the Rice Blast Fungus | MycorWeb Plant-Microbe Interactions | Scoop.it

Because of great challenges and workload in deleting genes on a large scale, the functions of most genes in pathogenic fungi are still unclear. In this study, we developed a high-throughput gene knockout system using a novel yeast-Escherichia-Agrobacterium shuttle vector, pKO1B, in the rice blast fungus Magnaporthe oryzae. Using this method, we deleted 104 fungal-specific Zn2Cys6 transcription factor (TF) genes in M. oryzae. We then analyzed the phenotypes of these mutants with regard to growth, asexual and infection-related development, pathogenesis, and 9 abiotic stresses. The resulting data provide new insights into how this rice pathogen of global significance regulates important traits in the infection cycle through Zn2Cys6TF genes. A large variation in biological functions of Zn2Cys6TF genes was observed under the conditions tested. Sixty-one of 104 Zn2Cys6 TF genes were found to be required for fungal development. In-depth analysis of TF genes revealed that TF genes involved in pathogenicity frequently tend to function in multiple development stages, and disclosed many highly conserved but unidentified functional TF genes of importance in the fungal kingdom. We further found that the virulence-required TF genes GPF1 and CNF2 have similar regulation mechanisms in the gene expression involved in pathogenicity. These experimental validations clearly demonstrated the value of a high-throughput gene knockout system in understanding the biological functions of genes on a genome scale in fungi, and provided a solid foundation for elucidating the gene expression network that regulates the development and pathogenicity of M. oryzae.

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The fungal perspective of arbuscular mycorrhizal colonization in ‘nonmycorrhizal’ plants

The fungal perspective of arbuscular mycorrhizal colonization in ‘nonmycorrhizal’ plants | MycorWeb Plant-Microbe Interactions | Scoop.it
Arbuscular mycorrhiza (AM) is arguably the most abundant symbiosis on Earth. It involves fungi in the Glomeromycota and c. 70% of vascular plants (Brundrett, 2009), in which the fungal partner aids in nutrient uptake, pathogen protection and possibly other services in exchange for plant carbon (C) (Smith & Read, 2008). A smaller, but not insignificant, number of plant species are considered to be nonmycorrhizal, especially those within the families Amaranthaceae, Chenopodiaceae, Carophyllaceae and Brassicaceae (Brundrett, 2009). However, fungal colonization that resembles AM is often observed in these ‘nonmycorrhizal’ plants when they co-occur with mycorrhizal plants (Hirrel et al., 1978; Miller et al., 1983), although arbuscules are rarely if ever present (Meney et al., 1993; Muthukumar et al., 1996; Sengupta & Chaudhuri, 2002). Because arbuscules are the structures where AM fungi deliver phosphorus (P) to plants (Smith & Read, 2008), and since the hyphal and vesicular colonization is often observed in old or dying roots (Brundrett, 2004), the function of this symbiosis has been questioned (Hirrel et al., 1978; Koide & Schreiner, 1992; Brundrett, 2004). Nonetheless, responses to AM fungal inoculations by these plants range from negative (Allen et al., 1989) to positive (Williams et al., 1974), which suggests that mycorrhizal associations are not always asymptomatic, and that the distinction between mycorrhizal and nonmycorrhizal plants is more subtle than sometimes believed. Acknowledging its limitation, we will use the term ‘nonhost’ here to refer to plants that are thought to be nonmycorrhizal but often appear to be colonized by AM fungi.

Via Christophe Jacquet, Stéphane Hacquard
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Coming of age: orphan genes in plants

Coming of age: orphan genes in plants | MycorWeb Plant-Microbe Interactions | Scoop.it
Sizable minorities of protein-coding genes from every sequenced eukaryotic and prokaryotic genome are unique to the species. These so-called ‘orphan genes’ may evolve de novo from non-coding sequence or be derived from older coding material. They are often associated with environmental stress responses and species-specific traits or regulatory patterns. However, difficulties in studying genes where comparative analysis is impossible, and a bias towards broadly conserved genes, have resulted in underappreciation of their importance. We review here the identification, possible origins, evolutionary trends, and functions of orphans with an emphasis on their role in plant biology. We exemplify several evolutionary trends with an analysis of Arabidopsis thaliana and present QQS as a model orphan gene.
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Breaking new ground at the interface of dendroecology and mycology

Breaking new ground at the interface of dendroecology and mycology | MycorWeb Plant-Microbe Interactions | Scoop.it
New insight on the mycorrhizal fungus–host association, expected to emerge from combining dendrochronology, wood anatomy and mycology, may help to understanding better and disentangle biotic, abiotic, and combined edaphic factors of the mutualistic relation between ectomycorrhizal fungi and their perennial partners.
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« Les mycorhizes : la nouvelle révolution verte » de J André FORTIN, Christian PLENCHETTE et Yves PICHE.

« Les mycorhizes : la nouvelle révolution verte » de J André FORTIN, Christian PLENCHETTE et Yves PICHE. | MycorWeb Plant-Microbe Interactions | Scoop.it

Ce livre vise à la fois à comprendre la biologie des mycorhizes et à montrer comment en tirer profit dans de très nombreux aspects de la culture des plantes et de leur protection, tout en assurant le maintien des équilibres naturels. J. André FORTIN a enseigné à l’université Laval et à l’Université de Montréal et est reconnu internationalement pour ses travaux sur les mycorhises.


Via Isabelle Pélissié, Christophe Jacquet
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Jean-Michel Ané's curator insight, October 8, 2014 11:22 PM
A good book... in French!
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A Secreted Protein with Plant-Specific Cysteine-Rich Motif Functions as a Mannose-Binding Lectin That Exhibits Antifungal Activity

A Secreted Protein with Plant-Specific Cysteine-Rich Motif Functions as a Mannose-Binding Lectin That Exhibits Antifungal Activity | MycorWeb Plant-Microbe Interactions | Scoop.it
Plants have a variety of mechanisms for defending against plant pathogens and tolerating environmental stresses such as drought and high salinity. Ginkbilobin2 (Gnk2) is a seed storage protein in gymnosperm that possesses antifungal activity and a plant-specific cysteine-rich motif (domain of unknown function26 [DUF26]). The Gnk2-homologous sequence is also observed in an extracellular region of cysteine-rich repeat receptor-like kinases that function in response to biotic and abiotic stresses. Here, we report the lectin-like molecular function of Gnk2 and the structural basis of its monosaccharide recognition. Nuclear magnetic resonance experiments showed that mannan was the only yeast (Saccharomyces cerevisiae) cell wall polysaccharide that interacted with Gnk2. Gnk2 also interacted with mannose, a building block of mannan, with a specificity that was similar to those of mannose-binding legume lectins, by strictly recognizing the configuration of the hydroxy group at the C4 position of the monosaccharide. The crystal structure of Gnk2 in complex with mannose revealed that three residues (asparagine-11, arginine-93, and glutamate-104) recognized mannose by hydrogen bonds, which defined the carbohydrate-binding specificity. These interactions were directly related to the ability of Gnk2 to inhibit the growth of fungi, including the plant pathogenic Fusarium spp., which were disrupted by mutation of arginine-93 or the presence of yeast mannan in the assay system. In addition, Gnk2 did not inhibit the growth of a yeast mutant strain lacking the α1,2-linked mannose moiety. These results provide insights into the molecular basis of the DUF26 protein family
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Differential expression of metallothioneins in response to heavy metals and their involvement in metal tolerance in the symbiotic basidiomycete Laccaria bicolor

Differential expression of metallothioneins in response to heavy metals and their involvement in metal tolerance in the symbiotic basidiomycete Laccaria bicolor | MycorWeb Plant-Microbe Interactions | Scoop.it

Cysteine-rich peptides such as metallothioneins (MTs) are involved in metal homeostasis and detoxification in many eukaryotes. We report the characterization and expression of two MT genes, LbMT1 and LbMT2 from the ectomycorrhizal fungus Laccaria bicolor under metal stress conditions. LbMT1and LbMT2 differ with respect to the length of the encoded peptides (58 versus 37 aa, respectively) and also by their expression patterns in response to metals. The expression levels of both LbMT1 and LbMT2 increased as a function of increased external Cu concentration, the expression levels for LbMT2 were always significantly higher compared with those of LbMT1. Only LbMT1, but not LbMT2, responded to Cd supply in the range of 25–100 µM while Zn did not affect the transcription of either LbMT1 or LbMT2. Both genes also responded to oxidative stress, but to a lesser extent compared to their responses to either Cu or Cd stress. Heterologous complementation assays in metal-sensitive yeast mutants indicated that both LbMT1 and LbMT2 encode peptides capable of conferring higher tolerance to both Cu and Cd. The present study identified LbMTs as potential determinants of the response of this mycorrhizal fungus to Cu and Cd stress.

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Novel findings on the role of signal exchange in arbuscular and ectomycorrhizal symbioses

Novel findings on the role of signal exchange in arbuscular and ectomycorrhizal symbioses | MycorWeb Plant-Microbe Interactions | Scoop.it

The availability of genome sequences from both arbuscular and ectomycorrhizal fungi and their hosts has, together with elegant biochemical and molecular biological analyses, provided new information on signal exchange between the partners in mycorrhizal associations. The progress in understanding cellular processes has been more rapid in arbuscular than ectomycorrhizal symbiosis due to its similarities of early processes with Rhizobium-legume symbiosis. In ectomycorrhiza, the role of auxin and ethylene produced by both fungus and host plant is becoming understood at the molecular level, although the actual ligands and receptors leading to ectomycorrhizal symbiosis have not yet been discovered. For both systems, the functions of small effector proteins secreted from the respective fungus and taken up into the plant cell may be pivotal in understanding the attenuation of host defense. We review the subject by comparing cross-talk between fungal and plant partners during formation and establishment of arbuscular and ectomycorrhizal symbioses.

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2015 DOE JGI’s Science Portfolio Delves Deeper into the Earth’s Data Mine - DOE Joint Genome Institute

2015 DOE JGI’s Science Portfolio Delves Deeper into the Earth’s Data Mine - DOE Joint Genome Institute | MycorWeb Plant-Microbe Interactions | Scoop.it
The U.S. Department of Energy Joint Genome Institute (DOE JGI), a DOE Office of Science user facility, has announced that 32 new projects have been selected for the 2015 Community Science Program (CSP). From sampling Antarctic lakes to Caribbean waters, and from plant root micro-ecosystems, to the subsurface underneath the water table in forested watersheds,...
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Identification and Characterisation of a Hyper-Variable Apoplastic Effector Gene Family of the Potato Cyst Nematodes

Identification and Characterisation of a Hyper-Variable Apoplastic Effector Gene Family of the Potato Cyst Nematodes | MycorWeb Plant-Microbe Interactions | Scoop.it

Sedentary endoparasitic nematodes are obligate biotrophs that modify host root tissues, using a suite of effector proteins to create and maintain a feeding site that is their sole source of nutrition. Using assumptions about the characteristics of genes involved in plant-nematode biotrophic interactions to inform the identification strategy, we provide a description and characterisation of a novel group of hyper-variable extracellular effectors termed HYP, from the potato cyst nematode Globodera pallida. HYP effectors comprise a large gene family, with a modular structure, and have unparalleled diversity between individuals of the same population: no two nematodes tested had the same genetic complement of HYP effectors. Individuals vary in the number, size, and type of effector subfamilies. HYP effectors are expressed throughout the biotrophic stages in large secretory cells associated with the amphids of parasitic stage nematodes as confirmed by in situ hybridisation. The encoded proteins are secreted into the host roots where they are detectable by immunochemistry in the apoplasm, between the anterior end of the nematode and the feeding site. We have identified HYP effectors in three genera of plant parasitic nematodes capable of infecting a broad range of mono- and dicotyledon crop species. In planta RNAi targeted to all members of the effector family causes a reduction in successful parasitism.


Via Christophe Jacquet
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Population genomics of Populus trichocarpa identifies signatures of selection and adaptive trait associations : Nature Genetics

Population genomics of Populus trichocarpa identifies signatures of selection and adaptive trait associations : Nature Genetics | MycorWeb Plant-Microbe Interactions | Scoop.it
Forest trees are dominant components of terrestrial ecosystems that have global ecological and economic importance. Despite distributions that span wide environmental gradients, many tree populations are locally adapted, and mechanisms underlying this adaptation are poorly understood. Here we use a combination of whole-genome selection scans and association analyses of 544 Populus trichocarpa trees to reveal genomic bases of adaptive variation across a wide latitudinal range. Three hundred ninety-seven genomic regions showed evidence of recent positive and/or divergent selection and enrichment for associations with adaptive traits that also displayed patterns consistent with natural selection. These regions also provide unexpected insights into the evolutionary dynamics of duplicated genes and their roles in adaptive trait variation.
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Detecting short spatial scale local adaptation and epistatic selection in climate-related candidate genes in European beech (Fagus sylvatica) populations

Detecting short spatial scale local adaptation and epistatic selection in climate-related candidate genes in European beech (Fagus sylvatica) populations | MycorWeb Plant-Microbe Interactions | Scoop.it

Detecting signatures of selection in tree populations threatened by climate change is currently a major research priority. Here, we investigated the signature of local adaptation over a short spatial scale using 96 European beech (Fagus sylvatica L.) individuals originating from two pairs of populations on the northern and southern slopes of Mont Ventoux (south-eastern France). We performed both single and multilocus analysis of selection based on 53 climate-related candidate genes containing 546 SNPs. FST outlier methods at the SNP level revealed a weak signal of selection, with three marginally significant outliers in the northern populations. At the gene level, considering haplotypes as alleles, two additional marginally significant outliers were detected, one on each slope. To account for the uncertainty of haplotype inference, we averaged the Bayes factors over many possible phase reconstructions. Epistatic selection offers a realistic multilocus model of selection in natural populations. Here, we used a test suggested by Ohta based on the decomposition of the variance of linkage disequilibrium. Overall populations, 0.23% of the SNP pairs (haplotypes) showed evidence of epistatic selection, with nearly 80% of them being within genes. One of the between gene epistatic selection signals arose between an FST outlier and a nonsynonymous mutation in a drought response gene. Additionally, we identified haplotypes containing selectively advantageous allele combinations which were unique to high or low elevations and northern or southern populations. Several haplotypes contained nonsynonymous mutations situated in genes with known functional importance for adaptation to climatic factors.

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MinION USB stick gene sequencer finally comes to market

MinION USB stick gene sequencer finally comes to market | MycorWeb Plant-Microbe Interactions | Scoop.it
Oxford Nanopore Technologies has finally delivered on its promise to bring personalized genome sequencing to the desktop. It is now time to see what their MinIon USB device can do.

Via Jean-Michel Ané
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Jean-Michel Ané's curator insight, September 26, 2014 1:03 AM

Watch the video... Now you know what I want for Christmas!

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A first look at the Oxford Nanopore MinION sequencer

A first look at the Oxford Nanopore MinION sequencer | MycorWeb Plant-Microbe Interactions | Scoop.it

Oxford Nanopore's third-generation single-molecule sequencing platform promises to decrease costs for reagents and instrumentation. After a 2-year hiatus following the initial announcement, the first devices have been released as part of an early access program. We explore the performance of this platform by resequencing the lambda phage genome, and amplicons from a snake venom gland transcriptome. Although the handheld MinION sequencer can generate more than 150 megabases of raw data in one run, at most a quarter of the resulting reads map to the reference, with less than average 10% identity. Much of the sequence consists of insertion/deletion errors, or is seemingly without similarity to the template. Using the lambda phage data as an example, although the reads are long, averaging 5 kb, at best 890 ± 1932 bases per mapped read could be matched to the reference without soft clipping. In the course of a 36 h run on the MinION, it was possible to resequence the 48 kb lambda phage reference at 16× coverage. Currently, substantially larger projects would not be feasible using the MinION. Without increases in accuracy, which would be required for applications such as genome scaffolding and phasing, the current utility of the MinION appears limited. Library preparation requires access to a molecular laboratory, and is of similar complexity and cost to that of other next-generation sequencing platforms. The MinION is an exciting step in a new direction for single-molecule sequencing, though it will require dramatic decreases in error rates before it lives up to its promise.


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New Phytol: Community assembly of ectomycorrhizal fungi along a subtropical secondary forest succession

New Phytol: Community assembly of ectomycorrhizal fungi along a subtropical secondary forest succession | MycorWeb Plant-Microbe Interactions | Scoop.it

Environmental selection and dispersal limitation are two of the primary processes structuring biotic communities in ecosystems, but little is known about these processes in shaping soil microbial communities during secondary forest succession. We examined the communities of ectomycorrhizal (EM) fungi in young, intermediate and old forests in a Chinese subtropical ecosystem, using 454 pyrosequencing. The EM fungal community consisted of 393 operational taxonomic units (OTUs), belonging to 21 EM fungal lineages, in which three EM fungal lineages and 11 EM fungal OTUs showed significantly biased occurrence among the young, intermediate and old forests. The EM fungal community was structured by environmental selection and dispersal limitation in old forest, but only by environmental selection in young, intermediate, and whole forests. Furthermore, the EM fungal community was affected by different factors in the different forest successional stages, and the importance of these factors in structuring EM fungal community dramatically decreased along the secondary forest succession series. This study suggests that different assembly mechanisms operate on the EM fungal community at different stages in secondary subtropical forest succession.


Via Stéphane Hacquard
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Nutrient transfer in plant–fungal symbioses

Nutrient transfer in plant–fungal symbioses | MycorWeb Plant-Microbe Interactions | Scoop.it

Almost all plant species form symbioses with soil fungi, and nutrient transfer to plants is largely mediated through this partnership. Studies of fungal nutrient transfer to plants have largely focused on the transfer of limiting soil nutrients, such as nitrogen and phosphorous, by mycorrhizal fungi. However, certain fungal endophytes, such as Metarhizium and Beauveria, are also able to transfer nitrogen to their plant hosts. Here, we review recent studies that have identified genes and their encoded transporters involved in the movement of nitrogen, phosphorous, and nonlimiting soil nutrients between symbionts. These recent advances in our understanding could lead to applications in agricultural and horticultural settings, and to the development of model fungal systems that could further elucidate the role of fungi in these symbioses.

  
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Long-distance endosome trafficking drives fungal effector production during plant infection

Long-distance endosome trafficking drives fungal effector production during plant infection | MycorWeb Plant-Microbe Interactions | Scoop.it

To cause plant disease, pathogenic fungi can secrete effector proteins into plant cells to suppress plant immunity and facilitate fungal infection. Most fungal pathogens infect plants using very long strand-like cells, called hyphae, that secrete effectors from their tips into host tissue. How fungi undergo long-distance cell signalling to regulate effector production during infection is not known. Here we show that long-distance retrograde motility of early endosomes (EEs) is necessary to trigger transcription of effector-encoding genes during plant infection by the pathogenic fungus Ustilago maydis. We demonstrate that motor-dependent retrograde EE motility is necessary for regulation of effector production and secretion during host cell invasion. We further show that retrograde signalling involves the mitogen-activated kinase Crk1 that travels on EEs and participates in control of effector production. Fungal pathogens therefore undergo long-range signalling to orchestrate host invasion.


Via Kamoun Lab @ TSL
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Environmental drivers of ectomycorrhizal communities in Europe's temperate oak forests

Environmental drivers of ectomycorrhizal communities in Europe's temperate oak forests | MycorWeb Plant-Microbe Interactions | Scoop.it

Ectomycorrhizal fungi are major ecological players in temperate forests but they are rarely used in measures of forest condition because large-scale, high-resolution, standardized and replicated belowground data is scarce. We carried out an analysis of ectomycorrhizas at 22 intensively-monitored long-term oak plots, across nine European countries, covering complex natural and anthropogenic environmental gradients. We found that at large scales mycorrhizal richness and evenness declined with decreasing soil pH and root density, and with increasing atmospheric nitrogen deposition. Shifts in mycorrhizas with different functional traits were detected; mycorrhizas with structures specialized for long-distance transport related differently to most environmental variables than those without. The dominant oak-specialist Lactarius quietus, with limited soil exploration, responds positively to increasing N inputs and decreasing pH. In contrast, Tricholoma,Cortinarius and Piloderma species, with medium-distance soil exploration, show a consistently negative response. We also determined N critical loads for moderate (9.5 – 13.5 kg N ha−1 yr−1) and drastic (17 kg N ha−1 yr−1) changes in belowground mycorrhizal root communities in temperate oak forests. Overall, we generated the first baseline data for ectomycorrhizal fungi in the oak forests sampled, identified nitrogen pollution as one of their major drivers at large scales, and revealed fungi that individually and/or in combination with others can be used as belowground indicators of environmental characteristics.

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The Largest Subunit of RNA Polymerase II as a New Marker Gene to Study Assemblages of Arbuscular Mycorrhizal Fungi in the Field

The Largest Subunit of RNA Polymerase II as a New Marker Gene to Study Assemblages of Arbuscular Mycorrhizal Fungi in the Field | MycorWeb Plant-Microbe Interactions | Scoop.it
Due to the potential of arbuscular mycorrhizal fungi (AMF, Glomeromycota) to improve plant growth and soil quality, the influence of agricultural practice on their diversity continues to be an important research question. Up to now studies of community diversity in AMF have exclusively been based on nuclear ribosomal gene regions, which in AMF show high intra-organism polymorphism, seriously complicating interpretation of these data. We designed specific PCR primers for 454 sequencing of a region of the largest subunit of RNA polymerase II gene, and established a new reference dataset comprising all major AMF lineages. This gene is known to be monomorphic within fungal isolates but shows an excellent barcode gap between species. We designed a primer set to amplify all known lineages of AMF and demonstrated its applicability in combination with high-throughput sequencing in a long-term tillage experiment. The PCR primers showed a specificity of 99.94% for glomeromycotan sequences. We found evidence of significant shifts of the AMF communities caused by soil management and showed that tillage effects on different AMF taxa are clearly more complex than previously thought. The high resolving power of high-throughput sequencing highlights the need for quantitative measurements to efficiently detect these effects.
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Microbial genome-enabled insights into plant-microorganism interactions

Microbial genome-enabled insights into plant-microorganism interactions | MycorWeb Plant-Microbe Interactions | Scoop.it
Advances in genome-based studies on plant-associated microorganisms have transformed our understanding of many plant pathogens and are beginning to greatly widen our knowledge of plant interactions with mutualistic and commensal microorganisms. Pathogenomics has revealed how pathogenic microorganisms adapt to particular hosts, subvert innate immune responses and change host range, as well as how new pathogen species emerge. Similarly, culture-independent community profiling methods, coupled with metagenomic and metatranscriptomic studies, have provided the first insights into the emerging field of research on plant-associated microbial communities. Together, these approaches have the potential to bridge the gap between plant microbial ecology and plant pathology, which have traditionally been two distinct research fields.

Via Jean-Michel Ané
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Lulwoana sp., a dark septate endophyte in roots of Posidonia oceanica seagrass

Lulwoana sp., a dark septate endophyte in roots of Posidonia oceanica seagrass | MycorWeb Plant-Microbe Interactions | Scoop.it
Posidonia oceanica is the most common, widespread and important monocotyledon seagrass in the Mediterranean Basin, and hosts a large biodiversity of species, including microorganisms with key roles in the marine environment. In this study, we ascertain the presence of a fungal endophyte in the roots of P. oceanica growing on different substrata (rock, sand and matte) in two Sicilian marine meadows. Staining techniques on root fragments and sections, in combination with microscope observations, were used to visualise the fungal presence and determine the percentage of fungal colonisation (FC) in this tissue. In root fragments, statistical analysis of the FC showed a higher mean in roots anchored on rock than on matte and sand. In root sections, an inter- and intracellular septate mycelium, producing intracellular microsclerotia, was detected from the rhizodermis to the vascular cylinder. Using isolation techniques, we obtained, from both sampling sites, sterile, slow-growing fungal colonies, dark in colour, with septate mycelium, belonging to the dark septate endophytes (DSEs). DNA sequencing of the internal transcribed spacer (ITS) region identified these colonies as Lulwoana sp. To our knowledge, this is the first report of Lulwoana sp. as DSE in roots of P. oceanica. Moreover, the highest fungal colonisation, detected in P. oceanica roots growing on rock, suggests that the presence of the DSE may help the host in several ways, particularly in capturing mineral nutrients through lytic activity.
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1K FG project: Protocols for fruiting body sampling

1K FG project: Protocols for fruiting body sampling | MycorWeb Plant-Microbe Interactions | Scoop.it

Recently 1KFG has begun exploring using fresh fruiting body sampled tissue to obtain DNA rather than requiring pure culture-based samples only. This can be problematic for a variety of reasons including the heterokaryon nature of fruiting tissue, possible contamination with bacteria, insects, or other fungi, and the limitations to return to the exact sample for additional sampling since it will either be destroyed in the sampling or only have a small amount left for a voucher specimen.

 
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Different shades of JAZ during plant growth and defense

Different shades of JAZ during plant growth and defense | MycorWeb Plant-Microbe Interactions | Scoop.it
Simplified model of how interactions between JASMONATE ZIM-domain proteins (JAZs) and DELLA proteins mediate crosstalk between shade-triggered elongation growth and jasmonate (JA)-dependent defenses. (a) Under conditions of high red : far-red (R : FR) light ratios (no shade), gibberellin (GA) concentrations are relatively low, allowing DELLAs to interact with Phytochrome Interacting Factors (PIFs) and JAZs. As a result, the cellular capacity of JAZs to inhibit the activity of MYCs and other transcription factors is relatively low. Induction of JA biosynthesis, for example, upon insect herbivory or infection by a necrotrophic pathogen, results in degradation of JAZs via the 26S proteasome, leading to a relatively high level of JA-dependent defenses against insect herbivores and necrotrophic pathogens. (b) During growth of plants in dense vegetation stands, the resulting low R : FR ratios of the light spectrum are sensed by the phytochrome photoreceptors (predominantly phyB), which initiate GA biosynthesis and signaling. Consequently, DELLAs are degraded by the 26S proteasome. On the one hand, this leads to the release of PIF transcription factors that activate GA-responsive growth-promoting genes that are associated with rapid elongation growth towards the light, which helps the plant to outcompete its neighboring vegetation; and on the other hand, JAZ–DELLA protein complexes become cured from DELLAs, resulting in enhanced binding of MYCs and other transcription factors to JAZs. In addition, JAZs become stabilized while MYCs are more rapidly turned over. Consequently, JA-induced defenses are suppressed, resulting in enhanced susceptibility to insect herbivores and necrotrophic pathogens.
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Phylogenetic trait conservation in the partner choice of a group of ectomycorrhizal trees

Phylogenetic trait conservation in the partner choice of a group of ectomycorrhizal trees | MycorWeb Plant-Microbe Interactions | Scoop.it
Ecological interactions are frequently conserved across evolutionary time. In the case of mutualisms, these conserved interactions may play a large role in structuring mutualist communities. We hypothesized that phylogenetic trait conservation could play a key role in determining patterns of association in the ectomycorrhizal symbiosis, a globally important trophic mutualism. We used the association between members of the pantropical plant tribe Pisonieae and its fungal mutualist partners as a model system to test the prediction that Pisonieae-associating ectomycorrhizal fungi will be more closely related than expected by chance, reflecting a conserved trait. We tested this prediction using previously published and newly generated sequences in a Bayesian framework incorporating phylogenetic uncertainty. We report that phylogenetic trait conservation does exist in this association. We generated a five-marker phylogeny of members of the Pisonieae and used this phylogeny in a Bayesian relaxed molecular clock analysis. We established that the most recent common ancestors of Pisonieae species and Pisonieae-associating fungi sharing phylogenetic conservation of their patterns of ectomycorrhizal association occurred no more recently than 14.2 Ma. We therefore suggest that phylogenetic trait conservation in the Pisonieae ectomycorrhizal mutualism association represents an inherited syndrome which has existed for at least 14 Myr.
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Two are better than one: combining landscape genomics and common gardens for detecting local adaptation in forest trees

Two are better than one: combining landscape genomics and common gardens for detecting local adaptation in forest trees | MycorWeb Plant-Microbe Interactions | Scoop.it

Predicting likely species responses to an alteration of their local environment is key to decision-making in resource management, ecosystem restoration and biodiversity conservation practice in the face of global human-induced habitat disturbance. This is especially true for forest trees which are a dominant life form on Earth and play a central role in supporting diverse communities and structuring a wide range of ecosystems. In Europe, it is expected that most forest tree species will not be able to migrate North fast enough to follow the estimated temperature isocline shift given current predictions for rapid climate warming. In this context, a topical question for forest genetics research is to quantify the ability for tree species to adapt locally to strongly altered environmental conditions (Kremer et al. 2012). Identifying environmental factors driving local adaptation is, however, a major challenge for evolutionary biology and ecology in general but is particularly difficult in trees given their large individual and population size and long generation time. Empirical evaluation of local adaptation in trees has traditionally relied on fastidious long-term common garden experiments (provenance trials) now supplemented by reference genome sequence analysis for a handful of economically valuable species. However, such resources have been lacking for most tree species despite their ecological importance in supporting whole ecosystems. In this issue of Molecular Ecology, De Kort et al. (2014) provide original and convincing empirical evidence of local adaptation to temperature in black alder, Alnus glutinosaL. Gaertn, a surprisingly understudied keystone species supporting riparian ecosystems. Here, De Kort et al. (2014) use an innovative empirical approach complementing state-of-the-art landscape genomics analysis of A. glutinosa populations sampled in natura across a regional climate gradient with phenotypic trait assessment in a common garden experiment (Fig. 1). By combining the two methods, De Kort et al. (2014) were able to detect unequivocal association between temperature and phenotypic traits such as leaf size as well as with genetic loci putatively under divergent selection for temperature. The research by De Kort et al. (2014) provides valuable insight into adaptive response to temperature variation for an ecologically important species and demonstrates the usefulness of an integrated approach for empirical evaluation of local adaptation in nonmodel species (Sork et al. 2013).

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