Plant immunity and legume symbiosis
87.9K views | +2 today
Follow
Plant immunity and legume symbiosis
Dedicated to plant mechanisms involved in response to pathogens, pests or symbionts. This site is complementary to the Plant pathogens and pests scoop-it site  :        http://www.scoop.it/t/erbilate. The role of hormones involved in regulation of plant responses to microorganisms is also reported in the "Plant hormones " site at http://www.scoop.it/t/plant-hormones-by-christophe-jacquet .
Your new post is loading...
Your new post is loading...
Scooped by Christophe Jacquet
Scoop.it!

Resistosome and inflammasome: platforms mediating innate immunity - ScienceDirect

Resistosome and inflammasome: platforms mediating innate immunity - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
The nucleotide-binding domain (NBD) and leucine-rich repeat (LRR) containing (NLR) proteins are intracellular immune receptors that sense pathogens or stress-associated signals in animals and plants. Direct or indirect binding of these stimuli to NLRs results in formation of higher-order large protein complexes termed inflammasomes in animals and resistosomes in plants to mediate immune signaling. Here we focus on plant NLRs and discuss the activation mechanism of the ZAR1 resistosome from Arabidopsis thaliana. We also outline the analogies and differences between the ZAR1 resistosome and the NLR inflammasomes, and discuss how the structural and biochemical information available on these two large types of protein complexes sheds light on signaling mechanisms of other plant NLRs.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

The Receptor Kinases BAK1/SERK4 Regulate Ca2+ Channel-Mediated Cellular Homeostasis for Cell Death Containment - ScienceDirect

The Receptor Kinases BAK1/SERK4 Regulate Ca2+ Channel-Mediated Cellular Homeostasis for Cell Death Containment - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
Cell death is a vital and ubiquitous process that is tightly controlled in all organisms. However, the mechanisms underlying precise cell death control remain fragmented. As an important shared module in plant growth, development, and immunity, Arabidopsis thaliana BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1 (BAK1) and somatic embryogenesis receptor kinase 4 (SERK4) redundantly and negatively regulate plant cell death. By deploying an RNAi-based genetic screen for bak1/serk4 cell death suppressors, we revealed that cyclic nucleotide-gated channel 20 (CNGC20) functions as a hyperpolarization-activated Ca2+-permeable channel specifically regulating bak1/serk4 cell death. BAK1 directly interacts with and phosphorylates CNGC20 at specific sites in the C-terminal cytosolic domain, which in turn regulates CNGC20 stability. CNGC19, the closest homolog of CNGC20 with a low abundance compared with CNGC20, makes a quantitative genetic contribution to bak1/serk4 cell death only in the absence of CNGC20, supporting the biochemical data showing homo- and heteromeric assembly of the CNGC20 and CNGC19 channel complexes. Transcripts of CNGC20 and CNGC19 are elevated in bak1/serk4 compared with wild-type plants, further substantiating a critical role of homeostasis of CNGC20 and CNGC19 in cell death control. Our studies not only uncover a unique regulation of ion channel stability by cell-surface-resident receptor kinase-mediated phosphorylation but also provide evidence for fine-tuning Ca2+ channel functions in maintaining cellular homeostasis by the formation of homo- and heterotetrameric complexes.
Scooped by Christophe Jacquet
Scoop.it!

Beneficial microbes going underground of root immunity - Yu - 2019 - Plant, Cell & Environment

Beneficial microbes going underground of root immunity - Yu - 2019 - Plant, Cell & Environment | Plant immunity and legume symbiosis | Scoop.it
Plant roots interact with an enormous diversity of commensal, mutualistic, and pathogenic microbes, which poses a big challenge to roots to distinguish beneficial microbes from harmful ones. Plants can effectively ward off pathogens following immune recognition of conserved microbe‐associated molecular patterns (MAMPs). However, such immune elicitors are essentially not different from those of neutral and beneficial microbes that are abundantly present in the root microbiome. Recent studies indicate that the plant immune system plays an active role in influencing rhizosphere microbiome composition. Moreover, it has become increasingly clear that root‐invading beneficial microbes, including rhizobia and arbuscular mycorrhiza, evade or suppress host immunity to establish a mutualistic relationship with their host. Evidence is accumulating that many free‐living rhizosphere microbiota members can suppress root immune responses, highlighting root immune suppression as an important function of the root microbiome. Thus, the gate keeping functions of the plant immune system are not restricted to warding off root‐invading pathogens but also extend to rhizosphere microbiota, likely to promote colonization by beneficial microbes and prevent growth‐defense tradeoffs triggered by the MAMP‐rich rhizosphere environment.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

NODULE INCEPTION Recruits the Lateral Root Developmental Program for Symbiotic Nodule Organogenesis in Medicago truncatula - ScienceDirect

NODULE INCEPTION Recruits the Lateral Root Developmental Program for Symbiotic Nodule Organogenesis in Medicago truncatula - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
To overcome nitrogen deficiencies in the soil, legumes enter symbioses with rhizobial bacteria that convert atmospheric nitrogen into ammonium. Rhizobia are accommodated as endosymbionts within lateral root organs called nodules that initiate from the inner layers of Medicago truncatula roots in response to rhizobial perception. In contrast, lateral roots emerge from predefined founder cells as an adaptive response to environmental stimuli, including water and nutrient availability. CYTOKININ RESPONSE 1 (CRE1)-mediated signaling in the pericycle and in the cortex is necessary and sufficient for nodulation, whereas cytokinin is antagonistic to lateral root development, with cre1 showing increased lateral root emergence and decreased nodulation. To better understand the relatedness between nodule and lateral root development, we undertook a comparative analysis of these two root developmental programs. Here, we demonstrate that despite differential induction, lateral roots and nodules share overlapping developmental programs, with mutants in LOB-DOMAIN PROTEIN 16 (LBD16) showing equivalent defects in nodule and lateral root initiation. The cytokinin-inducible transcription factor NODULE INCEPTION (NIN) allows induction of this program during nodulation through activation of LBD16 that promotes auxin biosynthesis via transcriptional induction of STYLISH (STY) and YUCCAs (YUC). We conclude that cytokinin facilitates local auxin accumulation through NIN promotion of LBD16, which activates a nodule developmental program overlapping with that induced during lateral root initiation.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A complex eIF4E locus impacts the durability of va resistance to Potato virus Y in tobacco - Michel - 2019 - Molecular Plant Pathology

A complex eIF4E locus impacts the durability of va resistance to Potato virus Y in tobacco - Michel - 2019 - Molecular Plant Pathology | Plant immunity and legume symbiosis | Scoop.it
Many recessive resistances against potyviruses are mediated by eukaryotic translation initiation factor 4E (eIF4E). In tobacco, the va resistance gene commonly used to control Potato virus Y (PVY) corresponds to a large deletion affecting the eIF4E‐1 gene on chromosome 21. Here, we compared the resistance durability conferred by various types of mutations affecting eIF4E‐1 (deletions of various sizes, frameshift or nonsense mutations). The ‘large deletion’ genotypes displayed the broadest and most durable resistance, whereas frameshift and nonsense mutants displayed a less durable resistance, with rapid and frequent apparition of resistance‐breaking variants. In addition, genetic and transcriptomic analyses revealed that resistance durability is strongly impacted by a complex genetic locus on chromosome 14, which contains three other eIF4E genes. One of these, eIF4E‐3, is rearranged as a hybrid gene between eIF4E‐2 and eIF4E‐3 (eIF4E‐2‐3) in the genotypes showing the most durable resistance, while eIF4E‐2 is differentially expressed between the tested varieties. RNA‐seq and quantitative reverse transcriptase‐polymerase chain reaction experiments demonstrated that eIF4E‐2 expression level is positively correlated with resistance durability. These results suggest that besides the nature of the mutation affecting eIF4E‐1, three factors linked with a complex locus may potentially impact va durability: loss of an integral eIF4E‐3, presence of eIF4E‐2‐3 and overexpression of eIF4E‐2. This latter gene might act as a decoy in a non‐productive virus–plant interaction, limiting the ability of PVY to evolve towards resistance breaking. Taken together, these results show that va resistance durability can in large part be explained by complex redundancy effects in the eIF4E gene family.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Bacterial infection systemically suppresses stomatal density - Dutton - 2019 - Plant, Cell & Environment -

Bacterial infection systemically suppresses stomatal density - Dutton - 2019 - Plant, Cell & Environment - | Plant immunity and legume symbiosis | Scoop.it
Many plant pathogens gain entry to their host via stomata. On sensing attack, plants close these pores to restrict pathogen entry. Here, we show that plants exhibit a second longer term stomatal response to pathogens. Following infection, the subsequent development of leaves is altered via a systemic signal. This reduces the density of stomata formed, thus providing fewer entry points for pathogens on new leaves. Arabidopsis thaliana leaves produced after infection by a bacterial pathogen that infects through the stomata (Pseudomonas syringae) developed larger epidermal pavement cells and stomata and consequently had up to 20% reductions in stomatal density. The bacterial peptide flg22 or the phytohormone salicylic acid induced similar systemic reductions in stomatal density suggesting that they might mediate this effect. In addition, flagellin receptors, salicylic acid accumulation, and the lipid transfer protein AZI1 were all required for this developmental response. Furthermore, manipulation of stomatal density affected the level of bacterial colonization, and plants with reduced stomatal density showed slower disease progression. We propose that following infection, development of new leaves is altered by a signalling pathway with some commonalities to systemic acquired resistance. This acts to reduce the potential for future infection by providing fewer stomatal openings.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A set of Arabidopsis genes involved in the accommodation of the downy mildew pathogen Hyaloperonospora arabidopsidis

A set of Arabidopsis genes involved in the accommodation of the downy mildew pathogen Hyaloperonospora arabidopsidis | Plant immunity and legume symbiosis | Scoop.it
The intracellular accommodation structures formed by plant cells to host arbuscular mycorrhiza fungi and biotrophic hyphal pathogens are cytologically similar. Therefore we investigated whether these interactions build on an overlapping genetic framework. In legumes, the malectin-like domain leucine-rich repeat receptor kinase SYMRK, the cation channel POLLUX and members of the nuclear pore NUP107-160 subcomplex are essential for symbiotic signal transduction and arbuscular mycorrhiza development. We identified members of these three groups in Arabidopsis thaliana and explored their impact on the interaction with the oomycete downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa). We report that mutations in the corresponding genes reduced the reproductive success of Hpa as determined by sporangiophore and spore counts. We discovered that a developmental transition of haustorial shape occurred significantly earlier and at higher frequency in the mutants. Analysis of the multiplication of extracellular bacterial pathogens, Hpa-induced cell death or callose accumulation, as well as Hpa- or flg22-induced defence marker gene expression, did not reveal any traces of constitutive or exacerbated defence responses. These findings point towards an overlap between the plant genetic toolboxes involved in the interaction with biotrophic intracellular hyphal symbionts and pathogens in terms of the gene families involved.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

An Evolutionarily Ancient Immune System Governs the Interactions between Pseudomonas syringae and an Early-Diverging Land Plant Lineage

Evolutionary molecular plant-microbe interactions (EvoMPMI) is an emerging field bridging the gap between molecular phytopathology and evolutionary studies. EvoMPMI research is currently challenging due to the scarcity of pathogenic model systems in early-diverging land plants. Liverworts are among the earliest diverging land-plant lineages, and Marchantia polymorpha has emerged as a liverwort model for evolutionary studies. However, bacterial pathogens of Marchantia have not yet been discovered, and the molecular mechanisms controlling plant-pathogen interactions in this early-diverging land plant remain unknown. Here, we describe a robust experimental plant-bacterial pathosystem for EvoMPMI studies and discover that an ancient immune system governs plant-microbe interactions between M. polymorpha and the hemi-biotrophic pathogenic bacteria Pseudomonas syringae. We show that P. syringae pv tomato (Pto) DC3000, causal agent of tomato bacterial speck disease, colonizes M. polymorpha and activates typical hallmarks of plant innate immunity. Virulence of Pto DC3000 on M. polymorpha relies on effector activities inside liverwort cells, including conserved AvrPto and AvrPtoB functions. Host specificity analyses uncovered pathogenic differences among P. syringae strains, suggesting that M. polymorpha-P. syringae interactions are controlled by the genetic backgrounds of both host and pathogen. Finally, we show that ancient phytohormone defensive networks govern M. polymorpha-P. syringae interactions. Altogether, our results demonstrate that the basic structure of the plant immune system of extant angiosperms is evolutionarily ancient and conserved in early-diverging land plants. This basic immune system may have been instrumental for land colonization by the common ancestor of land plants.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A protein complex required for polar growth of rhizobial infection threads

A protein complex required for polar growth of rhizobial infection threads | Plant immunity and legume symbiosis | Scoop.it
During root nodule symbiosis, intracellular accommodation of rhizobia by legumes is a prerequisite for nitrogen fixation. For many legumes, rhizobial colonization initiates in root hairs through transcellular infection threads. In Medicago truncatula, VAPYRIN (VPY) and a putative E3 ligase LUMPY INFECTIONS (LIN) are required for infection thread development but their cellular and molecular roles are obscure. Here we show that LIN and its homolog LIN-LIKE interact with VPY and VPY-LIKE in a subcellular complex localized to puncta both at the tip of the growing infection thread and at the nuclear periphery in root hairs and that the punctate accumulation of VPY is positively regulated by LIN. We also show that an otherwise nuclear and cytoplasmic exocyst subunit, EXO70H4, systematically co-localizes with VPY and LIN during rhizobial infection. Genetic analysis shows that defective rhizobial infection in exo70h4 is similar to that in vpy and lin. Our results indicate that VPY, LIN and EXO70H4 are part of the symbiosis-specific machinery required for polar growth of infection threads.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A deletion mutation in TaHRC confers Fhb1 resistance to Fusarium head blight in wheat

A deletion mutation in TaHRC confers Fhb1 resistance to Fusarium head blight in wheat | Plant immunity and legume symbiosis | Scoop.it
Fusarium head blight (FHB), which is mainly caused by Fusarium graminearum, is a destructive wheat disease that threatens global wheat production. Fhb1, a quantitative trait locus discovered in Chinese germplasm, provides the most stable and the largest effect on FHB resistance in wheat. Here we show that TaHRC, a gene that encodes a putative histidine-rich calcium-binding protein, is the key determinant of Fhb1-mediated resistance to FHB. We demonstrate that TaHRC encodes a nuclear protein conferring FHB susceptibility and that a deletion spanning the start codon of this gene results in FHB resistance. Identical sequences of the TaHRC-R allele in diverse accessions indicate that Fhb1 had a single origin, and phylogenetic and haplotype analyses suggest that the TaHRC-R allele most likely originated from a line carrying the Dahongpao haplotype. This discovery opens a new avenue to improve FHB resistance in wheat, and possibly in other cereal crops, by manipulating TaHRC sequence through bioengineering approaches.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Systems Biology of Plant-Microbiome Interactions - ScienceDirect

Systems Biology of Plant-Microbiome Interactions - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
In natural environments, plants are exposed to diverse microbiota that they interact with in complex ways. While plant–pathogen interactions have been intensely studied to understand defense mechanisms in plants, many microbes and microbial communities can have substantial beneficial effects on their plant host. Such beneficial effects include improved acquisition of nutrients, accelerated growth, resilience against pathogens, and improved resistance against abiotic stress conditions such as heat, drought, and salinity. However, the beneficial effects of bacterial strains or consortia on their host are often cultivar and species specific, posing an obstacle to their general application. Remarkably, many of the signals that trigger plant immune responses are molecularly highly similar and often identical in pathogenic and beneficial microbes. Thus, it is unclear what determines the outcome of a particular microbe–host interaction and which factors enable plants to distinguish beneficials from pathogens. To unravel the complex network of genetic, microbial, and metabolic interactions, including the signaling events mediating microbe–host interactions, comprehensive quantitative systems biology approaches will be needed.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Frontiers | Host-Induced Gene Silencing of MoAP1 Confers Broad-Spectrum Resistance to Magnaporthe oryzae | Plant Science

Frontiers | Host-Induced Gene Silencing of MoAP1 Confers Broad-Spectrum Resistance to Magnaporthe oryzae | Plant Science | Plant immunity and legume symbiosis | Scoop.it
Rice blast caused by Magnaporthe oryzae (M. oryzae) is a major threat to global rice production. In recent years, small interference RNAs (siRNAs) and host-induced gene silencing (HIGS) has been shown to be new strategies for the development of transgenic plants to control fungal diseases and proved a useful tool to study gene function in pathogens. We here tested whether in vitro feeding artificial siRNAs (asiRNAs) could compromise M. oryzae virulence and in vivo HIGS technique could improve rice blast resistance. Our data revealed that silencing of M. oryzae MoAP1 by feeding asiRNAs targeting MoAP1 (i.e., asiR1245, asiR1362, and asiR1115) resulted in inhibited fungal growth, abnormal spores, and decreased pathogenicity. Among the asiRNAs, asiR1115 was the most inhibitory toward the rice blast fungus. Conversely, the asiRNAs targeting three other genes (i.e., MoSSADH, MoACT, and MoSOM1) had no effect on fungal growth. Transgenic rice plants expressing RNA hairpins targeting MoAP1 exhibited improved resistance to 11 tested M. oryzae strains. Confocal microscopy also revealed profoundly restricted appressoria and mycelia in rice blast-infected transgenic rice plants. Our results demonstrate that in vitro asiRNA and in vivo HIGS were useful protection approaches that may be valuable to enhance rice blast resistance.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Genes involved in nonhost disease resistance as a key to engineer durable resistance in crops - ScienceDirect

Genes involved in nonhost disease resistance as a key to engineer durable resistance in crops - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
Most potential pathogens fail to establish virulence for a plethora of plants found in nature. This intrinsic property to resist pathogen virulence displayed by organisms without triggering canonical resistance (R) genes has been termed nonhost resistance (NHR). While host resistance involves recognition of pathogen elicitors such as avirulence factors by bona fide R proteins, mechanism of NHR seems less obvious, often involving more than one gene. We can generally describe NHR in two steps: 1) pre-invasive resistance, either passive or active, which can restrict the pathogen from entering the host, and 2) post-invasive resistance, an active defense response that often results in hypersensitive response like programmed cell death and reactive oxygen species accumulation. While PAMP-triggered-immunity (PTI) is generally effective against nonhost pathogens, effector-triggered-immunity (ETI) can be effective against both host and nonhost pathogens. Prolonged interactions between adapted pathogens and their resistant host plants results in co-evolution, which can lead to new pathogen strains that can be virulent and cause disease on supposedly resistant host. In this context, engineering durable resistance by manipulating genes involved in NHR is an attractive approach for sustainable agriculture. Several genes involved in NHR have been characterized for their role in plant defense. In this review, we report genes involved in NHR identified to date and highlight a few examples where genes involved in NHR have been used to confer resistance in crop plants against economically important diseases.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A receptor-like kinase enhances sunflower resistance to Orobanche cumana

A receptor-like kinase enhances sunflower resistance to Orobanche cumana | Plant immunity and legume symbiosis | Scoop.it
Orobanche cumana (sunflower broomrape) is an obligate parasitic plant that infects sunflower roots, causing yield losses. Here, by using a map-based cloning strategy, we identified HaOr7—a gene that confers resistance to O. cumana race F—which was found to encode a leucine-rich repeat receptor-like kinase. The complete HAOR7 protein is present in resistant lines of sunflower and prevents O. cumana from connecting to the vascular system of sunflower roots, whereas susceptible lines encode a truncated protein that lacks transmembrane and kinase domains.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

NODULE INCEPTION Recruits the Lateral Root Developmental Program for Symbiotic Nodule Organogenesis in Medicago truncatula - ScienceDirect

NODULE INCEPTION Recruits the Lateral Root Developmental Program for Symbiotic Nodule Organogenesis in Medicago truncatula - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
To overcome nitrogen deficiencies in the soil, legumes enter symbioses with rhizobial bacteria that convert atmospheric nitrogen into ammonium. Rhizobia are accommodated as endosymbionts within lateral root organs called nodules that initiate from the inner layers of Medicago truncatula roots in response to rhizobial perception. In contrast, lateral roots emerge from predefined founder cells as an adaptive response to environmental stimuli, including water and nutrient availability. CYTOKININ RESPONSE 1 (CRE1)-mediated signaling in the pericycle and in the cortex is necessary and sufficient for nodulation, whereas cytokinin is antagonistic to lateral root development, with cre1 showing increased lateral root emergence and decreased nodulation. To better understand the relatedness between nodule and lateral root development, we undertook a comparative analysis of these two root developmental programs. Here, we demonstrate that despite differential induction, lateral roots and nodules share overlapping developmental programs, with mutants in LOB-DOMAIN PROTEIN 16 (LBD16) showing equivalent defects in nodule and lateral root initiation. The cytokinin-inducible transcription factor NODULE INCEPTION (NIN) allows induction of this program during nodulation through activation of LBD16 that promotes auxin biosynthesis via transcriptional induction of STYLISH (STY) and YUCCAs (YUC). We conclude that cytokinin facilitates local auxin accumulation through NIN promotion of LBD16, which activates a nodule developmental program overlapping with that induced during lateral root initiation.
Scooped by Christophe Jacquet
Scoop.it!

Multiple genes recruited from hormone pathways partition maize diterpenoid defences

Multiple genes recruited from hormone pathways partition maize diterpenoid defences | Plant immunity and legume symbiosis | Scoop.it
Duplication and divergence of primary pathway genes underlie the evolution of plant specialized metabolism; however, mechanisms partitioning parallel hormone and defence pathways are often speculative. For example, the primary pathway intermediate ent-kaurene is essential for gibberellin biosynthesis and is also a proposed precursor for maize antibiotics. By integrating transcriptional coregulation patterns, genome-wide association studies, combinatorial enzyme assays, proteomics and targeted mutant analyses, we show that maize kauralexin biosynthesis proceeds via the positional isomer ent-isokaurene formed by a diterpene synthase pair recruited from gibberellin metabolism. The oxygenation and subsequent desaturation of ent-isokaurene by three promiscuous cytochrome P450s and a new steroid 5α reductase indirectly yields predominant ent-kaurene-associated antibiotics required for Fusarium stalk rot resistance. The divergence and differential expression of pathway branches derived from multiple duplicated hormone-metabolic genes minimizes dysregulation of primary metabolism via the circuitous biosynthesis of ent-kaurene-related antibiotics without the production of growth hormone precursors during defence.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

The plant hypersensitive response: concepts, control and consequences - Balint‐Kurti - 2019 - Molecular Plant Pathology

The plant hypersensitive response: concepts, control and consequences - Balint‐Kurti - 2019 - Molecular Plant Pathology | Plant immunity and legume symbiosis | Scoop.it
The hypersensitive defence response is found in all higher plants and is characterized by a rapid cell death at the point of pathogen ingress. It is usually associated with pathogen resistance, though, in specific situations, it may have other consequences such as pathogen susceptibility, growth retardation and, over evolutionary timescales, speciation. Due to the potentially severe costs of inappropriate activation, plants employ multiple mechanisms to suppress inappropriate activation of HR and to constrain it after activation. The ubiquity of this response among higher plants despite its costs suggests that it is an extremely effective component of the plant immune system.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A reference genome for pea provides insight into legume genome evolution

A reference genome for pea provides insight into legume genome evolution | Plant immunity and legume symbiosis | Scoop.it
We report the first annotated chromosome-level reference genome assembly for pea, Gregor Mendel’s original genetic model. Phylogenetics and paleogenomics show genomic rearrangements across legumes and suggest a major role for repetitive elements in pea genome evolution. Compared to other sequenced Leguminosae genomes, the pea genome shows intense gene dynamics, most likely associated with genome size expansion when the Fabeae diverged from its sister tribes. During Pisum evolution, translocation and transposition differentially occurred across lineages. This reference sequence will accelerate our understanding of the molecular basis of agronomically important traits and support crop improvement.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Genome‐wide analysis of flanking sequences reveals that Tnt1 insertion is positively correlated with gene methylation in Medicago truncatula - Sun - 2019 - The Plant Journal -

Genome‐wide analysis of flanking sequences reveals that Tnt1 insertion is positively correlated with gene methylation in Medicago truncatula - Sun - 2019 - The Plant Journal - | Plant immunity and legume symbiosis | Scoop.it
From a single transgenic line harboring five Tnt1 transposon insertions, we generated a near‐saturated insertion population in Medicago truncatula. Using thermal asymmetric interlaced‐polymerase chain reaction followed by sequencing, we recovered 388 888 flanking sequence tags (FSTs) from 21 741 insertion lines in this population. FST recovery from 14 Tnt1 lines using the whole‐genome sequencing (WGS) and/or Tnt1‐capture sequencing approaches suggests an average of 80 insertions per line, which is more than the previous estimation of 25 insertions. Analysis of the distribution pattern and preference of Tnt1 insertions showed that Tnt1 is overall randomly distributed throughout the M. truncatula genome. At the chromosomal level, Tnt1 insertions occurred on both arms of all chromosomes, with insertion frequency negatively correlated with the GC content. Based on 174 546 filtered FSTs that show exact insertion locations in the M. truncatula genome version 4.0 (Mt4.0), 0.44 Tnt1 insertions occurred per kb, and 19 583 genes contained Tnt1 with an average of 3.43 insertions per gene. Pathway and gene ontology analyses revealed that Tnt1‐inserted genes are significantly enriched in processes associated with ‘stress’, ‘transport’, ‘signaling’ and ‘stimulus response’. Surprisingly, gene groups with higher methylation frequency were more frequently targeted for insertion. Analysis of 19 583 Tnt1‐inserted genes revealed that 59% (1265) of 2144 transcription factors, 63% (765) of 1216 receptor kinases and 56% (343) of 616 nucleotide‐binding site‐leucine‐rich repeat genes harbored at least one Tnt1 insertion, compared with the overall 38% of Tnt1‐inserted genes out of 50 894 annotated genes in the genome.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Comparing Arabidopsis receptor kinase and receptor protein‐mediated immune signaling reveals BIK1‐dependent differences - Wan - 2019 - New Phytologist - Wiley Online Library

Comparing Arabidopsis receptor kinase and receptor protein‐mediated immune signaling reveals BIK1‐dependent differences - Wan - 2019 - New Phytologist - Wiley Online Library | Plant immunity and legume symbiosis | Scoop.it
Pattern recognition receptors (PRRs) sense microbial patterns and activate innate immunity against attempted microbial invasions. The leucine‐rich repeat receptor kinases (LRR‐RK) FLS2 and EFR, and the LRR receptor protein (LRR‐RP) receptors RLP23 and RLP42, respectively, represent prototypical members of these two prominent and closely related PRR families.
We conducted a survey of Arabidopsis thaliana immune signaling mediated by these receptors to address the question of commonalities and differences between LRR‐RK and LRR‐RP signaling.
Quantitative differences in timing and amplitude were observed for several early immune responses, with RP‐mediated responses typically being slower and more prolonged than those mediated by RKs. Activation of RLP23, but not FLS2, induced the production of camalexin. Transcriptomic analysis revealed that RLP23‐regulated genes represent only a fraction of those genes differentially expressed upon FLS2 activation. Several positive and negative regulators of FLS2‐signaling play similar roles in RLP23 signaling. Intriguingly, the cytoplasmic receptor kinase BIK1, a positive regulator of RK signaling, acts as a negative regulator of RP‐type immune receptors in a manner dependent on BIK1 kinase activity.
Our study unveiled unexpected differences in two closely related receptor systems and reports a new negative role of BIK1 in plant immunity.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Perturbations of the ZED1 pseudokinase activate plant immunity

Perturbations of the ZED1 pseudokinase activate plant immunity | Plant immunity and legume symbiosis | Scoop.it
The Pseudomonas syringae acetyltransferase HopZ1a is delivered into host cells by the type III secretion system to promote bacterial growth. However, in the model plant host Arabidopsis thaliana, HopZ1a activity results in an effector-triggered immune response (ETI) that limits bacterial proliferation. HopZ1a-triggered immunity requires the nucleotide-binding, leucine-rich repeat domain (NLR) protein, ZAR1, and the pseudokinase, ZED1. Here we demonstrate that HopZ1a can acetylate members of a family of ‘receptor-like cytoplasmic kinases’ (RLCK family VII; also known as PBS1-like kinases, or PBLs) and promote their interaction with ZED1 and ZAR1 to form a ZAR1-ZED1-PBL ternary complex. Interactions between ZED1 and PBL kinases are determined by the pseudokinase features of ZED1, and mutants designed to restore ZED1 kinase motifs can (1) bind to PBLs, (2) recruit ZAR1, and (3) trigger ZAR1-dependent immunity in planta, all independently of HopZ1a. A ZED1 mutant that mimics acetylation by HopZ1a also triggers immunity in planta, providing evidence that effector-induced perturbations of ZED1 also activate ZAR1. Overall, our results suggest that interactions between these two RLCK families are promoted by perturbations of structural features that distinguish active from inactive kinase domain conformations. We propose that effector-induced interactions between ZED1/ZRK pseudokinases (RLCK family XII) and PBL kinases (RLCK family VII) provide a sensitive mechanism for detecting perturbations of either kinase family to activate ZAR1-mediated ETI.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Mutation of a histidine-rich calcium-binding-protein gene in wheat confers resistance to Fusarium head blight

Mutation of a histidine-rich calcium-binding-protein gene in wheat confers resistance to Fusarium head blight | Plant immunity and legume symbiosis | Scoop.it
Head or ear blight, mainly caused by Fusarium species, can devastate almost all staple cereal crops (particularly wheat), resulting in great economic loss and imposing health threats on both human beings and livestock1,2,3. However, achievement in breeding for highly resistant cultivars is still not satisfactory. Here, we isolated the major-effect wheat quantitative trait locus, Qfhs.njau-3B, which confers head blight resistance, and showed that it is the same as the previously designated Fhb1. Fhb1 results from a rare deletion involving the 3′ exon of the histidine-rich calcium-binding-protein gene on chromosome 3BS. Both wheat and Arabidopsis transformed with the Fhb1 sequence showed enhanced resistance to Fusarium graminearum spread. The translation products of this gene’s homologs among plants are well conserved and might be essential for plant growth and development. Fhb1 could be useful not only for curbing Fusarium head blight in grain crops but also for improving other plants vulnerable to Fusarium species.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A Lotus japonicus cytoplasmic kinase connects Nod factor perception by the NFR5 LysM receptor to nodulation | PNAS

A Lotus japonicus cytoplasmic kinase connects Nod factor perception by the NFR5 LysM receptor to nodulation | PNAS | Plant immunity and legume symbiosis | Scoop.it
The establishment of nitrogen-fixing root nodules in legume–rhizobia symbiosis requires an intricate communication between the host plant and its symbiont. We are, however, limited in our understanding of the symbiosis signaling process. In particular, how membrane-localized receptors of legumes activate signal transduction following perception of rhizobial signaling molecules has mostly remained elusive. To address this, we performed a coimmunoprecipitation-based proteomics screen to identify proteins associated with Nod factor receptor 5 (NFR5) in Lotus japonicus. Out of 51 NFR5-associated proteins, we focused on a receptor-like cytoplasmic kinase (RLCK), which we named NFR5-interacting cytoplasmic kinase 4 (NiCK4). NiCK4 associates with heterologously expressed NFR5 in Nicotiana benthamiana, and directly binds and phosphorylates the cytoplasmic domains of NFR5 and NFR1 in vitro. At the cellular level, Nick4 is coexpressed with Nfr5 in root hairs and nodule cells, and the NiCK4 protein relocates to the nucleus in an NFR5/NFR1-dependent manner upon Nod factor treatment. Phenotyping of retrotransposon insertion mutants revealed that NiCK4 promotes nodule organogenesis. Together, these results suggest that the identified RLCK, NiCK4, acts as a component of the Nod factor signaling pathway downstream of NFR5.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Frontiers | Damage-Associated Molecular Pattern-Triggered Immunity in Plants | Plant Science

Frontiers | Damage-Associated Molecular Pattern-Triggered Immunity in Plants | Plant Science | Plant immunity and legume symbiosis | Scoop.it
As a universal process in multicellular organisms, including animals and plants, cells usually emit danger signals when suffering from attacks of microbes and herbivores, or physical damage. These signals, termed as damage-associated molecular patterns (DAMPs), mainly include cell wall or extracellular protein fragments, peptides, nucleotides, and amino acids. Once exposed on cell surfaces, DAMPs are detected by plasma membrane-localized receptors of surrounding cells to regulate immune responses against the invading organisms and promote damage repair. DAMPs may also act as long-distance mobile signals to mediate systemic wounding responses. Generation, release, and perception of DAMPs, and signaling events downstream of DAMP perception are all rigorously modulated by plants. These processes integrate together to determine intricate mechanisms of DAMP-triggered immunity in plants. In this review, we present an extensive overview on our current understanding of DAMPs in plant immune system.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Microbiota-mediated disease resistance in plants

Microbiota-mediated disease resistance in plants | Plant immunity and legume symbiosis | Scoop.it

Plant pathogens represent a constant and major threat to global food production, with 20%–30% global crop losses estimated, principally in food-deficit areas . Pesticide use, breeding of resistance genes, and genetic manipulation of plant immune components have helped to mitigate this threat. However, rapid evolution of pathogen resistance and virulence, together with host range expansion and host jumps, contribute to severe disease outbreaks, especially in the context of current agricultural practices . This underscores the need to reduce the lag time between the appearance of new diseases and development of protective measures effective on a broad range of pathogens and host plants.

In this context, microbial products and inoculants for plant protection have recently gained attention thanks to the large efforts made to systematically isolate, identify, and characterize plant-associated microbes that engage in intimate association with healthy plants . Recent findings indicate that individual- and community-level features provided by plant microbiota members can confer extended immune functions to the plant host. Importantly, the traits lent by “beneficial” microbes strongly depend on the interplay between the soil nutrient status and the plant immune system . Thus, the successful implementation of microbiota-mediated disease protection will depend on our mechanistic understanding of how microorganisms interact with their hosts and with one another in natural environments. Here, we seek to synthesize the state of this cross-disciplinary field to bridge the gap toward rational design of synthetic microbial communities (SynComs) with broad, durable, and flexible plant protective activities.

No comment yet.