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New Phytol - Comparative genomics of Rhizophagus irregularis, R. cerebriforme, R. diaphanus and Gigaspora rosea highlights specific genetic features in Glomeromycotina

New Phytol - Comparative genomics of Rhizophagus irregularis, R. cerebriforme, R. diaphanus and Gigaspora rosea highlights specific genetic features in Glomeromycotina | LRSV Publications | Scoop.it

 Glomeromycotina is a lineage of early diverging Fungi establishing arbuscular mycorrhizal (AM) symbiosis with land plants. Despite their major ecological role, genetic bases of their obligate mutualism are largely unknown, hindering our understanding of their evolution and biology.

• We compared the genomes of Glomerales (Rhizophagus irregularis, Rhizophagus diaphanus, Rhizophagus cerebriforme) and Diversisporales (Gigaspora rosea)species, together with those of saprotrophic Mucoromycota, to identify gene families and processes associated with these lineages and to understand the molecular underpinning of their symbiotic lifestyle.

• Genomic features in Glomeromycotina appear to be very similar with a very high content in transposons and protein‐coding genes, extensive duplications of protein kinase genes, and loss of genes coding for lignocellulose degradation, thiamin biosynthesis and cytosolic fatty acid synthase. Most symbiosis‐related genes in R. irregularis and G. rosea are specific to Glomeromycotina. We also confirmed that the present species have a homokaryotic genome organization.

• The high interspecific diversity of Glomeromycotina gene repertoires, affecting all known protein domains, as well as symbiosis‐related orphan genes, may explain the known adaptation of Glomeromycotina to a wide range of environmental settings. Our findings contribute to an increasingly detailed portrait of genomic features defining the biology of AM fungi.

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New Phytol - Arbuscular mycorrhizal fungi possess a CLAVATA3/Endosperm surrounding region‐related gene that positively regulates symbiosis

The arbuscular mycorrhizal (AM) symbiosis is a beneficial association established between land plants and the members of a subphylum of fungi, the Glomeromycotina. How the two symbiotic partners regulate their association is still enigmatic. Secreted fungal peptides are candidates for regulating this interaction.

We searched for fungal peptides with similarities with known plant signaling peptides.

We identified CLAVATA (CLV)/EMBRYO SURROUNDING REGION (ESR)‐RELATED PROTEIN (CLE) genes in phylogenetically distant AM fungi: four Rhizophagus species and one Gigaspora species. These CLE genes encode a signal peptide for secretion and the conserved CLE C‐terminal motif. They seem to be absent in the other fungal clades. R. irregularis and G. rosea CLE genes (RiCLE1 and GrCLE1) are transcriptionally induced in symbiotic versus asymbiotic conditions. Exogenous application of synthetic RiCLE1 peptide on Medicago truncatula affects root architecture, by slowing the apical growth of primary roots and stimulating the formation of lateral roots. In addition, pre‐treatement of seedlings with RiCLE1 peptide stimulates mycorrhization.

Our findings demonstrate for the first time that in addition to plants and nematodes, AM fungi also possess CLE genes. These results pave the way for deciphering new mechanisms by which AM fungi modulate plant cellular responses during the establishment of AM symbiosis.

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Proteomics - Cell Wall Proteome Investigation of Bread Wheat (Triticum Aestivum) Developing Grain in Endosperm and Outer Layers

The remodeling of cell wall polysaccharides is controlled by cell wall proteins (CWPs) during the development of wheat grain. This work describes for the first time the cell wall proteomes of the endosperm and outer layers of the wheat developing grain, which have distinct physiological functions and technological uses. Altogether 636 nonredundant predicted CWPs are identified with 337 proteins in the endosperm and 594 proteins in the outer layers, among which 295 proteins are present in both tissues, suggesting both common and tissue specific remodeling activities. These proteins are distributed into eight functional classes. Approximatively a quarter of them were predicted to act on cell wall polysaccharides, with many glycosylhydrolases and also expansin, lyases, and carbohydrate esterases. Therefore, these results provide crucial data to go further in the understanding of relationship between tissue‐specific morphogenesis and cell wall remodeling in cereals. Data are available via ProteomeXchange with identifier PXD010367.

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New Phytol - Lipo‐chitooligosaccharide signalling blocks a rapid pathogen‐induced ROS burst without impeding immunity

Molecular signals released by microbes at the surface of plant roots and leaves largely determine host responses, notably by triggering either immunity or symbiosis. How these signalling pathways cross‐talk upon coincident perception of pathogens and symbionts is poorly described in plants forming symbiosis.

Nitrogen fixing symbiotic Rhizobia spp. and Arbuscular Mycorrhizal fungi produce Lipo‐chitooligosaccharides (LCOs) to initiate host symbiotic programs. In Medicago truncatula roots, the perception of LCOs leads to reduced efflux of Reactive Oxygen Species (ROS). In contrast, pathogen perception generally triggers a strong ROS burst and activates defence gene expression.

Here we show that incubation of M. truncatula seedlings with culture filtrate (CF) of the legume pathogen Aphanomyces euteiches alone or simultaneously with Sinorhizobium meliloti LCOs, resulted in a strong ROS release. However, this response was completely inhibited if CF was added after pre‐incubation of seedlings with LCOs. In contrast, expression of immunity‐associated genes in response to CF and disease resistance to A. euteiches remained unaffected by LCO treatment of M. truncatula roots.

Our findings suggest that symbiotic plants evolved ROS inhibition response to LCOs to facilitate early steps of symbiosis whilst maintaining parallel defence mechanisms toward pathogens.

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PLoS Biology - Nitrogen fixation in a landrace of maize is supported by a mucilage-associated diazotrophic microbiota

PLoS Biology - Nitrogen fixation in a landrace of maize is supported by a mucilage-associated diazotrophic microbiota | LRSV Publications | Scoop.it

Plants are associated with a complex microbiota that contributes to nutrient acquisition, plant growth, and plant defense. Nitrogen-fixing microbial associations are efficient and well characterized in legumes but are limited in cereals, including maize. We studied an indigenous landrace of maize grown in nitrogen-depleted soils in the Sierra Mixe region of Oaxaca, Mexico. This landrace is characterized by the extensive development of aerial roots that secrete a carbohydrate-rich mucilage. Analysis of the mucilage microbiota indicated that it was enriched in taxa for which many known species are diazotrophic, was enriched for homologs of genes encoding nitrogenase subunits, and harbored active nitrogenase activity as assessed by acetylene reduction and 15N2 incorporation assays. Field experiments in Sierra Mixe using 15N natural abundance or 15N-enrichment assessments over 5 years indicated that atmospheric nitrogen fixation contributed 29%–82% of the nitrogen nutrition of Sierra Mixe maize.

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Nature Plants - Fern genomes elucidate land plant evolution and cyanobacterial symbioses

Nature Plants - Fern genomes elucidate land plant evolution and cyanobacterial symbioses | LRSV Publications | Scoop.it

Ferns are the closest sister group to all seed plants, yet little is known about their genomes other than that they are generally colossal. Here, we report on the genomes of Azolla filiculoides and Salvinia cucullata(Salviniales) and present evidence for episodic whole-genome duplication in ferns—one at the base of ‘core leptosporangiates’ and one specific to Azolla. One fern-specific gene that we identified, recently shown to confer high insect resistance, seems to have been derived from bacteria through horizontal gene transfer. Azolla coexists in a unique symbiosis with N2-fixing cyanobacteria, and we demonstrate a clear pattern of cospeciation between the two partners. Furthermore, the Azolla genome lacks genes that are common to arbuscular mycorrhizal and root nodule symbioses, and we identify several putative transporter genes specific to Azolla–cyanobacterial symbiosis. These genomic resources will help in exploring the biotechnological potential of Azolla and address fundamental questions in the evolution of plant life.

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Nature Plants - Oak genome reveals facets of long lifespan

Nature Plants - Oak genome reveals facets of long lifespan | LRSV Publications | Scoop.it

Oaks are an important part of our natural and cultural heritage. Not only are they ubiquitous in our most common landscapes1 but they have also supplied human societies with invaluable services, including food and shelter, since prehistoric times2. With 450 species spread throughout Asia, Europe and America3, oaks constitute a critical global renewable resource. The longevity of oaks (several hundred years) probably underlies their emblematic cultural and historical importance. Such long-lived sessile organisms must persist in the face of a wide range of abiotic and biotic threats over their lifespans. We investigated the genomic features associated with such a long lifespan by sequencing, assembling and annotating the oak genome. We then used the growing number of whole-genome sequences for plants (including tree and herbaceous species) to investigate the parallel evolution of genomic characteristics potentially underpinning tree longevity. A further consequence of the long lifespan of trees is their accumulation of somatic mutations during mitotic divisions of stem cells present in the shoot apical meristems. Empirical4 and modelling5 approaches have shown that intra-organismal genetic heterogeneity can be selected for6and provides direct fitness benefits in the arms race with short-lived pests and pathogens through a patchwork of intra-organismal phenotypes7. However, there is no clear proof that large-statured trees consist of a genetic mosaic of clonally distinct cell lineages within and between branches. Through this case study of oak, we demonstrate the accumulation and transmission of somatic mutations and the expansion of disease-resistance gene families in trees.

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BMC Biology - Genomics analysis of Aphanomyces spp. identifies a new class of oomycete effector associated with host adaptation 

Oomycetes are a group of filamentous eukaryotic microorganisms that have colonized all terrestrial and oceanic ecosystems, and they include prominent plant pathogens. The Aphanomyces genus is unique in its ability to infect both plant and animal species, and as such exemplifies oomycete versatility in adapting to different hosts and environments. Dissecting the underpinnings of oomycete diversity provides insights into their specificity and pathogenic mechanisms. By carrying out genomic analyses of the plant pathogen A. euteiches and the crustacean pathogen A. astaci, we show that host specialization is correlated with specialized secretomes that are adapted to the deconstruction of the plant cell wall in A. euteiches and protein degradation in A. astaci. The A. euteiches genome is characterized by a large repertoire of small secreted protein (SSP)-encoding genes that are highly induced during plant infection, and are not detected in other oomycetes. Functional analysis revealed an SSP from A. euteiches containing a predicted nuclear-localization signal which shuttles to the plant nucleus and increases plant susceptibility to infection. Collectively, our results show that Aphanomyces host adaptation is associated with evolution of specialized secretomes and identify SSPs as a new class of putative oomycete effectors.
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Chemosphere - Influence of arbuscular mycorrhizal fungi on antimony phyto-uptake and compartmentation in vegetables cultivated in urban gardens

Chemosphere - Influence of arbuscular mycorrhizal fungi on antimony phyto-uptake and compartmentation in vegetables cultivated in urban gardens | LRSV Publications | Scoop.it
1. Context Urban areas are often contaminated with various forms of persistent metal (loid) and emerging contaminants such as antimony (Sb). Thus, in the context of urban agriculture where sustainable practices such as biofertilizers application (arbuscular mycorrhizal fungi, AMF) could improve nutrient transfer from the soil to the vegetables, the effect of AMF on metal (loid) mobility and human bioaccessibility is still poorly known. 

 2. Methods The role of AMF in Sb uptake by lettuce and carrot grown in artificial substrate spiked with different Sb chemical species was investigated. Plants were grown under hydroponic conditions and half of the treatments received a concentrated spore solution to obtain mycorrhized and non-mycorrhized plants. Three weeks before harvest, plants were exposed to 10 mg.L−1 of either Sb2O3 or KSbO-tartrate (KSb). 

 3. Results The presence of AMF significantly increased its accumulation in carrots (all organs) with higher accumulation in roots. In lettuce, accumulation appeared to be dependent on the Sb chemical species. Moreover, it was observed for the first time that AMF changed the human bioaccessible fraction of Sb in edible organs. 

 4. Implications The present results highlight a possible risk of Sb transfer from soil to edible plants cultivated in soil naturally containing AMF propagules, or when AMF are added as biofertilizers. After validating the influence of soil environment and AMF on Sb behavior in the field, these results should be considered in health risk assessments.
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GigaScience - 10KP: A Phylodiverse Genome Sequencing Plan 

GigaScience - 10KP: A Phylodiverse Genome Sequencing Plan  | LRSV Publications | Scoop.it

Understanding plant evolution and diversity in a phylogenomic context is an enormous challenge, due in part to limited availability of genome-scale data across phylodiverse species. The 10KP (10,000 Plants) Genome Sequencing Project will sequence and characterize representative genomes from every major clade of embryophytes, green algae, and protists (excluding fungi) within the next five years. By implementing (and continuously improving) leading-edge sequencing technologies and bioinformatics tools, 10KP will catalogue the genome content of plant and protist diversity, and make these data freely available as an enduring foundation for future scientific discovery and application. 10KP is structured as an international consortium, open to the global community, including botanical gardens, plant research institutes, universities, and private industry. Our immediate goal is to establish a policy framework for this endeavour, the principles of which are outlined here.

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New Phytol - High intraspecific genome diversity in the model arbuscular mycorrhizal symbiont Rhizophagus irregularis

New Phytol - High intraspecific genome diversity in the model arbuscular mycorrhizal symbiont Rhizophagus irregularis | LRSV Publications | Scoop.it

Arbuscular mycorrhizal fungi (AMF) are known to improve plant fitness through the establishment of mycorrhizal symbioses. Genetic and phenotypic variations among closely related AMF isolates can significantly affect plant growth, but the genomic changes underlying this variability are unclear. To address this issue, we improved the genome assembly and gene annotation of the model strain Rhizophagus irregularis DAOM197198, and compared its gene content with five isolates of R. irregularis sampled in the same field. All isolates harbor striking genome variations, with large numbers of isolate-specific genes, gene family expansions, and evidence of interisolate genetic exchange. The observed variability affects all gene ontology terms and PFAM protein domains, as well as putative mycorrhiza-induced small secreted effector-like proteins and other symbiosis differentially expressed genes. High variability is also found in active transposable elements. Overall, these findings indicate a substantial divergence in the functioning capacity of isolates harvested from the same field, and thus their genetic potential for adaptation to biotic and abiotic changes. Our data also provide a first glimpse into the genome diversity that resides within natural populations of these symbionts, and open avenues for future analyses of plant–AMF interactions that link AMF genome variation with plant phenotype and fitness.

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Current Protein & Peptide Science: Plant Cell Wall Proteomics as a Strategy to Reveal Candidate Proteins Involved in Extracellular Lipid Metabolism

Current Protein & Peptide Science: Plant Cell Wall Proteomics as a Strategy to Reveal Candidate Proteins Involved in Extracellular Lipid Metabolism | LRSV Publications | Scoop.it

Plant cell walls are composite structures surrounding cells and involved in both mechanical support and perception of their environment. They are mainly composed of polysaccharides (90-95% of their mass) and proteins (5-10%). The cell wall proteins (CWPs) contribute to the arrangements and modifications of polymer networks and to cell-to-cell communication. The structure and composition of cell walls are not uniform in the whole plants, but rather specialized in different cell types to fulfil different functions. As examples, two kinds of cells are covered with extracellular structures composed of lipids: epidermal cells of aerial organs synthesize a cuticle on their outside surface whereas endodermal root cells form a suberin surrounding strip. In both cases, these particular hydrophobic layers contribute to the protection of the cells against attacks by pathogens or abiotic stresses and regulate physiological processes. If the intracellular biosynthesis of the molecules forming these layers starts to be welldescribed, the mechanisms of their assembly beyond the plasma membrane remain largely unknown. In this review, this issue is addressed on the basis on cell wall proteomics data which has allowed the identification of many CWPs possibly related to lipid metabolism during the last years, in particular in Arabidopsis thaliana and tomato. These data are combined with transcriptomics and genetics studies. The main known roles of extracellular proteins related to lipid metabolism are discussed.

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J Exp Bot - Medicago truncatula GRAS protein RAD1 supports arbuscular mycorrhiza symbiosis and Phytophthora palmivora susceptibility 

J Exp Bot - Medicago truncatula  GRAS protein RAD1 supports arbuscular mycorrhiza symbiosis and  Phytophthora palmivora  susceptibility  | LRSV Publications | Scoop.it

The roots of most land plants are colonized by symbiotic arbuscular mycorrhiza (AM) fungi. To facilitate this symbiosis, plant genomes encode a set of genes required for microbial perception and accommodation. However, the extent to which infection by filamentous root pathogens also relies on some of these genes remains an open question. Here, we used genome-wide association mapping to identify genes contributing to colonization of Medicago truncatula roots by the pathogenic oomycete Phytophthora palmivora. Single-nucleotide polymorphism (SNP) markers most significantly associated with plant colonization response were identified upstream of RAD1, which encodes a GRAS transcription regulator first negatively implicated in root nodule symbiosis and recently identified as a positive regulator of AM symbiosis. RAD1 transcript levels are up-regulated both in response to AM fungus and, to a lower extent, in infected tissues by P. palmivora where its expression is restricted to root cortex cells proximal to pathogen hyphae. Reverse genetics showed that reduction of RAD1 transcript levels as well as a rad1 mutant are impaired in their full colonization by AM fungi as well as by P. palmivora. Thus, the importance of RAD1 extends beyond symbiotic interactions, suggesting a general involvement in M. truncatula microbe-induced root development and interactions with unrelated beneficial and detrimental filamentous microbes.

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ACS Synthetic Biology - A standardized synthetic Eucalyptus transcription factor and promoter panel for re-engineering secondary cell wall regulation in biomass and bioenergy crops

ACS Synthetic Biology - A standardized synthetic Eucalyptus transcription factor and promoter panel for re-engineering secondary cell wall regulation in biomass and bioenergy crops | LRSV Publications | Scoop.it

Re-engineering transcriptional networks regulating secondary cell wall formation may allow the improvement of plant biomass in widely grown plantation crops such as Eucalyptus. However, there is currently a scarcity of freely available standardized biological parts (e.g. Phytobricks) compatible with Type IIS assembly approaches from forest trees, and there is a need to accelerate transcriptional network inference in non-model biomass crops. Here we describe the design and synthesis of a versatile three-panel biological parts collection of 221 secondary cell wall-related Eucalyptus grandis transcription factor coding sequences and 65 promoters that are compatible with GATEWAY, Golden Gate, MoClo and GoldenBraid DNA assembly methods and generally conform to accepted Phytobrick syntaxes. This freely available resource is intended to accelerate synthetic biology applications in multiple plant biomass crops and enable reconstruction of secondary cell wall transcriptional networks using high-throughput assays such as DNA Affinity Purification sequencing (DAP-seq) and enhanced yeast one-hybrid (eY1H) screening.

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Dev Cell - Pectin Demethylesterification Generates Platforms that Anchor Peroxidases to Remodel Plant Cell Wall Domains

Dev Cell - Pectin Demethylesterification Generates Platforms that Anchor Peroxidases to Remodel Plant Cell Wall Domains | LRSV Publications | Scoop.it

 

Plant cell walls are made of polysaccharidic-proteinaceous complex matrices. Molecular interactions governing their organization remain understudied. We take advantage of the highly dynamic cell walls of Arabidopsis seed mucilage secretory cells to propose a hierarchical multi-molecular interaction model within a cell wall domain. We show that the PECTINMETHYLESTERASE INHIBITOR6 activity creates a partially demethylesterified pectin pattern acting as a platform allowing positioning of PEROXIDASE36 in a remote primary cell wall domain during early development. This allows triggering the loosening of this domain during later development, in turn leading to proper physiological function upon mature seed imbibition and germination. We anticipate that this pioneer example of molecular scaffold within a cell wall domain is more widespread through other combinations of the individual molecular players all belonging to large multigenic families. These results highlight the role of cell wall polysaccharide-protein interactions in the organization of cell wall domains.
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New Phytol - Lipo‐chitooligosaccharides promote lateral root formation and modify auxin homeostasis in Brachypodium distachyon

Lipo‐chitooligosaccharides (LCOs) are microbial symbiotic signals that also influence root growth. In Medicago truncatula, LCOs stimulate lateral root formation (LRF) synergistically with auxin. However, the molecular mechanisms of this phenomenon and whether it is restricted to legume plants are not known.

We have addressed the capacity of the model monocot Brachypodium distachyon(Brachypodium) to respond to LCOs and auxin for LRF. For this, we used a combination of root phenotyping assays, live‐imaging and auxin quantification, and analysed the regulation of auxin homeostasis genes.

We show that LCOs and a low dose of the auxin precursor indole‐3‐butyric acid (IBA) stimulated LRF in Brachypodium, while a combination of LCOs and IBA led to different regulations. Both LCO and IBA treatments locally increased endogenous indole‐3‐acetic acid (IAA) content, whereas the combination of LCO and IBA locally increased the endogenous concentration of a conjugated form of IAA (IAA‐Ala). LCOs, IBA and the combination differentially controlled expression of auxin homeostasis genes.

These results demonstrate that LCOs are active on Brachypodium roots and stimulate LRF probably through regulation of auxin homeostasis. The interaction between LCO and auxin treatments observed in Brachypodium on root architecture opens interesting avenues regarding their possible combined effects during the arbuscular mycorrhizal symbiosis.

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ESPR - Vermicompost addition influences symbiotic fungi communities associated with leek cultivated in metal-rich soils

ESPR - Vermicompost addition influences symbiotic fungi communities associated with leek cultivated in metal-rich soils | LRSV Publications | Scoop.it

In the context of urban agriculture, where soils are frequently contaminated with metal(loid)s (TM), we studied the influence of vermicompost amendments on symbiotic fungal communities associated with plants grown in two metal-rich soils. Leek (Allium porrum L.) plants were grown with or without vermicompost in two metal-rich soils characterized by either geogenic or anthropogenic TM sources, to assess the influence of pollutant origin on soil-plant transfer. Fungal communities associated with the leek roots were identified by high throughput Illumina MiSeq and TM contents were measured using mass spectrometry. Vermicompost addition led to a dramatic change in the fungal community with a loss of diversity in the two tested soils. This effect could partially explain the changes in metal transfer at the soil-AMF-plant interface. Our results suggest being careful while using composts when growing edibles in contaminated soils. More generally, this study highlights the need for further research in the field of fungal communities to refine practical recommendations to gardeners.

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Cell - The Chara Genome: Secondary Complexity and Implications for Plant Terrestrialization

Cell - The Chara Genome: Secondary Complexity and Implications for Plant Terrestrialization | LRSV Publications | Scoop.it

 

Land plants evolved from charophytic algae, among which Charophyceae possess the most complex body plans. We present the genome of Chara braunii; comparison of the genome to those of land plants identified evolutionary novelties for plant terrestrialization and land plant heritage genes. C. braunii employs unique xylan synthases for cell wall biosynthesis, a phragmoplast (cell separation) mechanism similar to that of land plants, and many phytohormones. C. braunii plastids are controlled via land-plant-like retrograde signaling, and transcriptional regulation is more elaborate than in other algae. The morphological complexity of this organism may result from expanded gene families, with three cases of particular note: genes effecting tolerance to reactive oxygen species (ROS), LysM receptor-like kinases, and transcription factors (TFs). Transcriptomic analysis of sexual reproductive structures reveals intricate control by TFs, activity of the ROS gene network, and the ancestral use of plant-like storage and stress protection proteins in the zygote.

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New Phytol - Arbuscular mycorrhizal fungi: intraspecific diversity and pangenomes

New Phytol - Arbuscular mycorrhizal fungi: intraspecific diversity and pangenomes | LRSV Publications | Scoop.it

Arbuscular mycorrhizal fungi (AMF) are ubiquitous plant symbionts with an intriguing population biology. Conspecific AMF strains can vary substantially at the genetic and phenotypic levels, leading to direct and quantifiable variation in plant growth. Recent studies have shown that high intraspecific diversity is very common in AMF, and not only found in model species. Studies have also revealed how the phenotype of conspecific isolates varies depending on the plant host, highlighting the functional relevance of intraspecific phenotypic plasticity for the AMF ecology and mycorrhizal symbiosis. Recent work has also demonstrated that conspecific isolates of the model AMF Rhizophagus irregularis harbor large and highly variable pangenomes, highlighting the potential role of intraspecific genome diversity for the ecological adaptation of these symbionts.

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Science - Phylogenomics reveals multiple losses of nitrogen-fixing root nodule symbiosis

Science - Phylogenomics reveals multiple losses of nitrogen-fixing root nodule symbiosis | LRSV Publications | Scoop.it
The root nodule symbiosis of plants with nitrogen-fixing bacteria impacts global nitrogen cycles and food production but is restricted to a subset of genera within a single clade of flowering plants. To explore the genetic basis for this scattered occurrence, we sequenced the genomes of ten plant species covering the diversity of nodule morphotypes, bacterial symbionts and infection strategies. In a genome-wide comparative analysis of a total of 37 plant species, we discovered signatures of multiple independent loss-of-function events in the indispensable symbiotic regulator NODULE INCEPTION ( NIN ) in ten out of 13 genomes of non-nodulating species within this clade. The discovery that multiple independent losses shaped the present day distribution of nitrogen-fixing root nodule symbiosis in plants reveals a phylogenetically wider distribution in evolutionary history and a so far underestimated selection pressure against this symbiosis.
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Current Opinion in Plant Biology - Symbiosis genes for immunity and vice versa

Current Opinion in Plant Biology - Symbiosis genes for immunity and vice versa | LRSV Publications | Scoop.it
Highlights 
• Several LysM receptor proteins have a dual function in symbiosis and immunity. 
• Symbiotic transcription factors can also control pathogen infection. • Genes of hormonal pathways regulate both pathogen and symbiont colonisation. 
• Crosstalk between symbiosis and immunity also occurs within the flavonoid pathway. 

Basic molecular knowledge on plant–pathogen interactions has largely been gained from reverse and forward genetics in Arabidopsis thaliana. However, as this model plant is unable to establish endosymbiosis with mycorrhizal fungi or rhizobia, plant responses to mutualistic symbionts have been studied in parallel in other plant species, mainly legumes. The resulting analyses led to the identification of gene networks involved in various functions, from microbe recognition to signalling and plant responses, thereafter assigned to either mutualistic symbiosis or immunity, according to the nature of the initially inoculated microbe. The increasing development of new pathosystems and genetic resources in model legumes and the implementation of reverse genetics in plants such as rice and tomato that interact with both mycorrhizal fungi and pathogens, have highlighted the dual role of plant genes previously thought to be specific to mutualistic or pathogenic interactions. The next challenges will be to determine whether such genes have similar functions in both types of interaction and if not, whether the perception of microbial compounds or the involvement of specific plant signalling components is responsible for the appropriate plant responses to the encountered microorganisms.
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Current Opinion in Plant Biology - What have we learnt from studying the evolution of the arbuscular mycorrhizal symbiosis?

Current Opinion in Plant Biology - What have we learnt from studying the evolution of the arbuscular mycorrhizal symbiosis? | LRSV Publications | Scoop.it
Highlights 
• The molecular mechanisms governing the ability of plants to engage in the AM symbiosis originated in the first land plants. 
• A core set of symbiotic genes has been conserved in all studied AM host plants. 
• Loss of a core set of symbiotic genes correlates with the irreversible loss of the AM symbiosis. 
• AM loss could be linked to the evolution of novel nutrient acquisition strategies. 

The arbuscular mycorrhizal (AM) symbiosis is a nearly ubiquitous association formed by most land plants. Numerous insights into the molecular mechanisms governing this symbiosis have been obtained in recent years leading to the identification of a core set of plant genes essential for successful formation of the AM symbiosis by angiosperm hosts. Recent phylogenetic analyses indicate that while the origin of some of these symbiotic genes predated the first land plants, the rest appeared through processes including de novo evolution and gene duplication that occurred specifically in the land plants. Purifying selection on this core gene set has been maintained over millions of years of plant evolution to conserve the AM symbiosis. However, several independent losses of this association have been recorded in numerous embryophyte lineages. In these lineages, potential compensatory mechanisms have been identified that could have helped these plants overcome the adversities imposed by the loss of the AM symbiosis. This review will focus on the processes governing the conservation of the AM symbiosis in the land plant lineage.
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Proteomics - Cell Wall Proteome of Sugarcane Young and Mature Leaves and Stems

Proteomics - Cell Wall Proteome of Sugarcane Young and Mature Leaves and Stems | LRSV Publications | Scoop.it
By characterizing the cell wall proteomes of different sugarcane organs (leaves and stems) at two developmental stages (young vs mature/apical vs basal), it is possible to address unique characteristics in each of them. Four-month-old leaves show a higher proportion of oxido-reductases and proteins related to lipid metabolism (LM), besides a lower proportion of proteins acting on polysaccharides, in comparison to 4-month-old internodes. It is possible to note that sugarcane leaves and young stems have the highest LM rate than all species, which is assumed to be linked to cuticle formation. The data generated enrich the number of cell wall proteins (CWPs) identified in sugarcane, reaching 277. To our knowledge, sugarcane has now the second higher coverage of monocot CWP in plants.
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Biofouling - Metabolome and proteome changes between biofilm and planktonic phenotypes of the marine bacterium Pseudoalteromonas lipolytica TC8

A number of bacteria adopt various lifestyles such as planktonic free-living or sessile biofilm stages. This enables their survival and development in a wide range of contrasting environments. With the aim of highlighting specific metabolic shifts between these phenotypes and to improve the overall understanding of marine bacterial adhesion, a dual metabolomics/proteomics approach was applied to planktonic and biofilm cultures of the marine bacterium Pseudoalteromonas lipolytica TC8. The liquid chromatography mass spectrometry (LC-MS) based metabolomics study indicated that membrane lipid composition was highly affected by the culture mode: phosphatidylethanolamine (PEs) derivatives were over-produced in sessile cultures while ornithine lipids (OLs) were more specifically synthesized in planktonic samples. In parallel, differences between proteomes revealed that peptidases, oxidases, transcription factors, membrane proteins and the enzymes involved in histidine biosynthesis were over-expressed in biofilms while proteins involved in heme production, nutrient assimilation, cell division and arginine/ornithine biosynthesis were specifically up-regulated in free-living cells.
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J Exp Bot - Plant extracellular vesicles are incorporated by a fungal pathogen and inhibit its growth

J Exp Bot - Plant extracellular vesicles are incorporated by a fungal pathogen and inhibit its growth | LRSV Publications | Scoop.it

Extracellular vesicles (EV) are membrane particles released by cells into their environment and are considered to be key players in intercellular communication. EV are produced by all domains of life but limited knowledge about EV in plants is available, although their implication in plant defense has been suggested. We have characterized sunflower EV and tested whether they could interact with fungal cells. EV were isolated from extracellular fluids of seedlings and characterized by transmission electron microscopy and proteomic analysis. These nanovesicles appeared to be enriched in cell wall remodeling enzymes and defense proteins. Membrane-labeled EV were prepared and their uptake by the phytopathogenic fungus Sclerotinia sclerotiorum was verified. Functional tests further evaluated the ability of EV to affect fungal growth. Spores treated with plant EV showed growth inhibition, morphological changes, and cell death. Conclusive evidence on the existence of plant EV is presented and we demonstrate their ability to interact with and kill fungal cells. Our results introduce the concept of cell-to-cell communication through EV in plants.

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