Plant immunity and legume symbiosis
87.9K views | +1 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!

Signaling mechanisms underlying systemic acquired resistance to microbial pathogens - ScienceDirect

Signaling mechanisms underlying systemic acquired resistance to microbial pathogens - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
Plants respond to biotic stress by inducing a variety of responses, which not only protect against the immediate diseases but also provide immunity from future infections. One example is systemic acquired resistance (SAR), which provides long-lasting and broad-spectrum protection at the whole plant level. The induction of SAR prepares the plant for a more robust response to subsequent infections from related and unrelated pathogens. SAR involves the rapid generation of signals at the primary site of infection, which are transported to the systemic parts of the plant presumably via the phloem. SAR signal generation and perception requires an intact cuticle, a waxy layer covering all aerial parts of the plant. A chemically diverse set of SAR inducers has already been identified, including hormones (salicylic acid, methyl salicylate), primary/secondary metabolites (nitric oxide, reactive oxygen species, glycerol-3-phosphate, azelaic acid, pipecolic acid, dihyroabetinal), fatty acid/lipid derivatives (18 carbon unsaturated fatty acids, galactolipids), and proteins (DIR1-Defective in Induced Resistance 1, AZI1-Azelaic acid Induced 1). Some of these are demonstrably mobile and the phloem loading routes for three of these SAR inducers is known. Here we discuss the recent findings related to synthesis, transport, and the relationship between these various SAR inducers.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Thioredoxin-mediated redox signalling in plant immunity - ScienceDirect

Thioredoxin-mediated redox signalling in plant immunity - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
Activation of plant immune responses is associated with rapid production of vast amounts of reactive oxygen and nitrogen species (ROS/RNS) that dramatically alter cellular redox homeostasis. Even though excessive ROS/RNS accumulation can cause widespread cellular damage and thus constitute a major risk, plant cells have evolved to utilise these molecules as important signalling cues. Particularly their ability to modify redox-sensitive cysteine residues has emerged as a key mechanism to control the activity, conformation, protein-protein interaction and localisation of a growing number of immune signalling proteins. Regulated reversal of cysteine oxidation is dependent on activities of the conserved superfamily of Thioredoxin (TRX) enzymes that function as cysteine reductases. The plant immune system recruits specific TRX enzymes that have the potential to functionally regulate numerous immune signalling proteins. Although our knowledge of different TRX immune targets is now expanding, little remains known about how these enzymes select their substrates, what range of oxidized residues they target, and if they function selectively in different redox-mediated immune signalling pathways. In this review we discuss these questions by examining evidence showing TRX enzymes exhibit novel activities that play important roles in diverse aspects of plant immune signalling.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Plant NLRs: From discovery to application -

Plant NLRs: From discovery to application - | Plant immunity and legume symbiosis | Scoop.it
Plants require a complex immune system to defend themselves against a wide range of pathogens which threaten their growth and development. The nucleotide-binding leucine-rich repeat proteins (NLRs) are immune sensors that recognize effectors delivered by pathogens. The first NLR was cloned more than twenty years ago. Since this initial discovery, NLRs have been described as key components of plant immunity responsible for pathogen recognition and triggering defense responses. They have now been described in most of the well-studied mulitcellular plant species, with most having large NLR repertoires. As research has progressed so has the understanding of how NLRs interact with their recognition substrates and how they in turn activate downstream signalling. It has also become apparent that NLR regulation occurs at the transcriptional, post-transcriptional, translational, and post-translational levels. Even before the first NLR was cloned, breeders were utilising such genes to increase crop performance. Increased understanding of the mechanistic details of the plant immune system enable the generation of plants resistant against devastating pathogens. This review aims to give an updated summary of the NLR field.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

An Arabidopsis berberine bridge enzyme‐like protein specifically oxidizes cellulose oligomers and plays a role in immunity - Locci - 2019 - The Plant Journal - Wiley Online Library

An Arabidopsis berberine bridge enzyme‐like protein specifically oxidizes cellulose oligomers and plays a role in immunity - Locci - 2019 - The Plant Journal - Wiley Online Library | Plant immunity and legume symbiosis | Scoop.it
The plant cell wall is the barrier that pathogens must overcome to cause a disease, and to this end they secrete enzymes that degrade the various cell wall components. Due to the complexity of these components, several types of oligosaccharide fragments may be released during pathogenesis and some of these can act as damage‐associated molecular patterns (DAMPs). Well‐known DAMPs are the oligogalacturonides (OGs) released upon degradation of homogalacturonan and the products of cellulose breakdown, i.e. the cellodextrins (CDs). We have previously reported that four Arabidopsis berberine bridge enzyme‐like (BBE‐like) proteins (OGOX1–4) oxidize OGs and impair their elicitor activity. We show here that another Arabidopsis BBE‐like protein, which is expressed coordinately with OGOX1 during immunity, specifically oxidizes CDs with a preference for cellotriose (CD3) and longer fragments (CD4–CD6). Oxidized CDs show a negligible elicitor activity and are less easily utilized as a carbon source by the fungus Botrytis cinerea. The enzyme, named CELLOX (cellodextrin oxidase), is encoded by the gene At4 g20860. Plants overexpressing CELLOX display an enhanced resistance to B. cinerea, probably because oxidized CDs are a less valuable carbon source. Thus, the capacity to oxidize and impair the biological activity of cell wall‐derived oligosaccharides seems to be a general trait of the family of BBE‐like proteins, which may serve to homeostatically control the level of DAMPs to prevent their hyperaccumulation.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

PNAS Plus: Balancing trade-offs between biotic and abiotic stress responses through leaf age-dependent variation in stress hormone cross-talk

PNAS Plus: Balancing trade-offs between biotic and abiotic stress responses through leaf age-dependent variation in stress hormone cross-talk | Plant immunity and legume symbiosis | Scoop.it
In nature, plants must respond to multiple stresses simultaneously, which likely demands cross-talk between stress-response pathways to minimize fitness costs. Here we provide genetic evidence that biotic and abiotic stress responses are differentially prioritized in Arabidopsis thaliana leaves of different ages to maintain growth and reproduction under combined biotic and abiotic stresses. Abiotic stresses, such as high salinity and drought, blunted immune responses in older rosette leaves through the phytohormone abscisic acid signaling, whereas this antagonistic effect was blocked in younger rosette leaves by PBS3, a signaling component of the defense phytohormone salicylic acid. Plants lacking PBS3 exhibited enhanced abiotic stress tolerance at the cost of decreased fitness under combined biotic and abiotic stresses. Together with this role, PBS3 is also indispensable for the establishment of salt stress- and leaf age-dependent phyllosphere bacterial communities. Collectively, our work reveals a mechanism that balances trade-offs upon conflicting stresses at the organism level and identifies a genetic intersection among plant immunity, leaf microbiota, and abiotic stress tolerance.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A resistosome-activated ‘death switch’

A resistosome-activated ‘death switch’ | Plant immunity and legume symbiosis | Scoop.it
Pathogen perception triggers a monomeric nucleotide-binding leucine-rich plant immune receptor to form a pentameric wheel-like complex termed a resistosome, with the N-terminal α helices forming a funnel-shaped structure that may perturb plasma membrane integrity to cause hypersensitive cell death.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Plant Malectin-Like Receptor Kinases: From Cell Wall Integrity to Immunity and Beyond | Annual Review of Plant Biology

Plant Malectin-Like Receptor Kinases: From Cell Wall Integrity to Immunity and Beyond | Annual Review of Plant Biology | Plant immunity and legume symbiosis | Scoop.it
Plant cells are surrounded by cell walls protecting them from a myriad of environmental challenges. For successful habitat adaptation, extracellular cues are perceived at the cell wall and relayed to downstream signaling constituents to mediate dynamic cell wall remodeling and adapted intracellular responses. Plant malectin-like receptor kinases, also known as Catharanthus roseus receptor-like kinase 1-like proteins (CrRLK1Ls), take part in these perception and relay processes. CrRLK1Ls are involved in many different plant functions. Their ligands, interactors, and downstream signaling partners are being unraveled, and studies about CrRLK1Ls’ roles in plant species other than the plant model Arabidopsis thaliana are beginning to flourish. This review focuses on recent CrRLK1L-related advances in cell growth, reproduction, hormone signaling, abiotic stress responses, and, particularly, immunity. We also give an overview of the comparative genomics and evolution of CrRLK1Ls, and present a brief outlook for future research.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A Plant Immune Receptor Adopts a Two-Step Recognition Mechanism to Enhance Viral Effector Perception - ScienceDirect

A Plant Immune Receptor Adopts a Two-Step Recognition Mechanism to Enhance Viral Effector Perception - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
Plant intracellular nucleotide binding leucine-rich repeat (NLR) immune receptors play critical roles in pathogen surveillance. Most plant NLRs characterized so far were found to use a single domain/sensor to recognize pathogen effectors. Here we report that the Sw-5b NLR immune receptor uses two distinct domains to detect the viral movement protein NSm encoded by tospovirus. In addition to its leucine-rich repeat (LRR) domain that has been previously reported, the N-terminal Solanaceae domain (SD) of Sw-5b also interacts with NSm and a conserved 21-amino-acid region of NSm (NSm21). The specific interaction between Sw-5b SD and NSm is required for releasing the inhibitory effect of coiled-coil domain on the NB-ARC-LRR region. Furthermore, we found that the binding of NSm affects the nucleotide binding activity of the NB-ARC-LRR in vitro, while Sw-5b NB-ARC-LRR is activated only when NSm and NSm21 levels are high. Interestingly, Sw-5b SD could significantly enhance the ability of the NB-ARC-LRR to detect low levels of NSm effector and facilitate its activation and induction of defense response. An Sw-5b SD mutant that is disrupted in NSm recognition failed to enhance the ability of the NB-ARC-LRR to sense low levels of NSm and NSm21. Taken together, our results suggest that Sw-5b SD functions as an extra sensor and the NB-ARC-LRR as an activator, and that Sw-5b NLR adopts a two-step recognition mechanism to enhance viral effector perception.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

The Cotton Apoplastic Protein CRR1 Stabilizes Chitinase 28 to Facilitate Defense against the Fungal Pathogen Verticillium dahliae

The Cotton Apoplastic Protein CRR1 Stabilizes Chitinase 28 to Facilitate Defense against the Fungal Pathogen Verticillium dahliae | Plant immunity and legume symbiosis | Scoop.it
The apoplast serves as the first battlefield between the plant hosts and invading microbes; therefore, work on plant-pathogen interactions has increasingly focused on apoplastic immunity. In this study, we identified three proteins in the apoplast of cotton (Gossypium sp) root cells during interaction of the plant with the fungal pathogen Verticillium dahliae. Among these proteins, cotton host cells secrete chitinase 28 (Chi28) and the Cys-rich repeat protein 1 (CRR1), while the pathogen releases the protease VdSSEP1. Biochemical analysis demonstrated that VdSSEP1 hydrolyzed Chi28, but CRR1 protected Chi28 from cleavage by Verticillium dahliae secretory Ser protease 1 (VdSSEP1). In accordance with the in vitro results, CRR1 interacted with Chi28 in yeast and plant cells and attenuated the observed decrease in Chi28 level that occurred in the apoplast of plant cells upon pathogen attack. Knockdown of CRR1 or Chi28 in cotton plants resulted in higher susceptibility to V. dahliae infection, and overexpression of CRR1 increased plant resistance to V. dahliae, the fungus Botrytis cinerea, and the oomycete Phytophthora parasitica var nicotianae. By contrast, knockout of VdSSEP1 in V. dahliae destroyed the pathogenicity of this fungus. Together, our results provide compelling evidence for a multilayered interplay of factors in cotton apoplastic immunity.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Osa‐miR398b boosts H2O2 production and rice blast disease‐resistance via multiple superoxide dismutases - Li - 2019 - New Phytologist -

Osa‐miR398b boosts H2O2 production and rice blast disease‐resistance via multiple superoxide dismutases - Li - 2019 - New Phytologist - | Plant immunity and legume symbiosis | Scoop.it
miRNAs contribute to plant resistance against pathogens. Previously, we found that the function of miR398b in immunity in rice differs from that in Arabidopsis. However, the underlying mechanisms are unclear.
In this study, we characterized the mutants of miR398b target genes and demonstrated that multiple superoxide dismutase genes contribute to miR398b‐regulated rice immunity against the blast fungus Magnaporthe oryzae.
Out of the four target genes of miR398b, mutations in Cu/Zn‐Superoxidase Dismutase1 (CSD1), CSD2 and Os11g09780 (Superoxide DismutaseX, SODX) led to enhanced resistance to M. oryzae and increased hydrogen peroxide (H2O2) accumulation. By contrast, mutations in Copper Chaperone for Superoxide Dismutase (CCSD) resulted in enhanced susceptibility. Biochemical studies revealed that csd1, csd2 and sodx displayed altered expression of CSDs and other superoxide dismutase (SOD) family members, leading to increased total SOD enzyme activity that positively contributed to higher H2O2 production. By contrast, the ccsd mutant showed CSD protein deletion, resulting in decreased CSD and total SOD enzyme activity.
Our results demonstrate the roles of different SODs in miR398b‐regulated resistance to rice blast disease, and uncover an integrative regulatory network in which miR398b boosts total SOD activity to upregulate H2O2 concentration and thereby improve disease resistance.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Inducible overexpression of Ideal Plant Architecture1 improves both yield and disease resistance in rice

Inducible overexpression of Ideal Plant Architecture1 improves both yield and disease resistance in rice | Plant immunity and legume symbiosis | Scoop.it
Breeding crops with resistance is an efficient way to control diseases. However, increased resistance often has a fitness penalty. Thus, simultaneously increasing disease resistance and yield potential is a challenge in crop breeding. In this study, we found that downregulation of microRNA-156 (miR-156) and overexpression of Ideal Plant Architecture1 (IPA1) and OsSPL7, two target genes of miR-156, enhanced disease resistance against bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo), but reduced rice yield. We discovered that gibberellin signalling might be partially responsible for the disease resistance and developmental defects in IPA1 overexpressors. We then generated transgenic rice plants expressing IPA1 with the pathogen-inducible promoter of OsHEN1; these plants had both enhanced disease resistance and enhanced yield-related traits. Thus, we have identified miR-156–IPA1 as a novel regulator of the crosstalk between growth and defence, and we have established a new strategy for obtaining both high disease resistance and high yield.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Showcasing the application of synchrotron‐based X‐ray computed tomography in host–pathogen interactions: The role of wheat rachilla and rachis nodes in Type‐II resistance to Fusarium graminearum - ...

Showcasing the application of synchrotron‐based X‐ray computed tomography in host–pathogen interactions: The role of wheat rachilla and rachis nodes in Type‐II resistance to Fusarium graminearum - ... | Plant immunity and legume symbiosis | Scoop.it
Fusarium head blight, caused primarily by Fusarium graminearum (Fg), is one of the most devastating diseases of wheat. Host resistance in wheat is classified into five types (Type‐I to Type‐V), and a majority of moderately resistant genotypes carry Type‐II resistance (resistance to pathogen spread in the rachis) alleles, mainly from the Chinese cultivar Sumai 3. Histopathological studies in the past failed to identify the key tissue in the spike conferring resistance to pathogen spread, and most of the studies used destructive techniques, potentially damaging the tissue(s) under study. In the present study, nondestructive synchrotron‐based phase contrast X‐ray imaging and computed tomography techniques were used to confirm the part of the wheat spike conferring Type‐II resistance to Fg spread, thus showcasing the application of synchrotron‐based techniques to image host–pathogen interactions. Seven wheat genotypes of moderate resistance to Fusarium head blight were studied for changes in the void space volume fraction and grayscale/voxel intensity following Fg inoculation. Cell‐wall biopolymeric compounds were quantified using Fourier‐transform midinfrared spectroscopy for all genotype‐treatment combinations. The study revealed that the rachilla and rachis nodes together are structurally important in conferring Type‐II resistance. The structural reinforcement was not necessarily observed from lignin deposition but rather from an unknown mechanism.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

The cotton laccase gene GhLAC15 enhances Verticillium wilt resistance via an increase in defence‐induced lignification and lignin components in the cell walls of plants - Zhang - 2019 - Molecular P...

The cotton laccase gene GhLAC15 enhances Verticillium wilt resistance via an increase in defence‐induced lignification and lignin components in the cell walls of plants - Zhang - 2019 - Molecular P... | Plant immunity and legume symbiosis | Scoop.it
Verticillium dahliae is a phytopathogenic fungal pathogen that causes vascular wilt diseases responsible for considerable decreases in cotton yields. The lignification of cell wall appositions is a conserved basal defence mechanism in the plant innate immune response. However, the function of laccase in defence‐induced lignification has not been described. Screening of an SSH library of a resistant cotton cultivar, Jimian20, inoculated with V. dahliae revealed a laccase gene that was strongly induced by the pathogen. This gene was phylogenetically related to AtLAC15 and contained domains conserved by laccases; therefore, we named it GhLAC15. Quantitative reverse transcription‐polymerase chain reaction indicated that GhLAC15 maintained higher expression levels in tolerant than in susceptible cultivars. Overexpression of GhLAC15 enhanced cell wall lignification, resulting in increased total lignin, G monolignol and G/S ratio, which significantly improved the Verticillium wilt resistance of transgenic Arabidopsis. In addition, the levels of arabinose and xylose were higher in transgenic plants than in wild‐type plants, which resulted in transgenic Arabidopsis plants being less easily hydrolysed. Furthermore, suppression of the transcriptional level of GhLAC15 resulted in an increase in susceptibility in cotton. The content of monolignol and the G/S ratio were lower in silenced cotton plants, which led to resistant cotton cv. Jimian20 becoming susceptible. These results demonstrate that GhLAC15 enhances Verticillium wilt resistance via an increase in defence‐induced lignification and arabinose and xylose accumulation in the cell wall of Gossypium hirsutum. This study broadens our knowledge of defence‐induced lignification and cell wall modifications as defence mechanisms against V. dahliae.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A local score approach improves GWAS resolution and detects minor QTL: application to Medicago truncatula quantitative disease resistance to multiple Aphanomyces euteiches isolates

A local score approach improves GWAS resolution and detects minor QTL: application to Medicago truncatula quantitative disease resistance to multiple Aphanomyces euteiches isolates | Plant immunity and legume symbiosis | Scoop.it
Quantitative trait loci (QTL) with small effects, which are pervasive in quantitative phenotypic variation, are difficult to detect in genome-wide association studies (GWAS). To improve their detection, we propose to use a local score approach that accounts for the surrounding signal due to linkage disequilibrium, by accumulating association signals from contiguous single markers. Simulations revealed that, in a GWAS context with high marker density, the local score approach outperforms single SNP p-value-based tests for detecting minor QTL (heritability of 5–10%) and is competitive with regard to alternative methods, which also aggregate p-values. Using more than five million SNPs, this approach was applied to identify loci involved in Quantitative Disease Resistance (QDR) to different isolates of the plant root rot pathogen Aphanomyces euteiches, from a GWAS performed on a collection of 174 accessions of the model legume Medicago truncatula. We refined the position of a previously reported major locus, underlying MYB/NB-ARC/tyrosine kinase candidate genes conferring resistance to two closely related A. euteiches isolates belonging to pea pathotype I. We also discovered a diversity of minor resistance QTL, not detected using p-value-based tests, some of which being putatively shared in response to pea (pathotype I and III) and/or alfalfa (race 1 and 2) isolates. Candidate genes underlying these QTL suggest pathogen effector recognition and plant proteasome as key functions associated with M. truncatula resistance to A. euteiches. GWAS on any organism can benefit from the local score approach to uncover many weak-effect QTL.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Phospholipase D and phosphatidic acid in plant immunity - ScienceDirect

Phospholipase D and phosphatidic acid in plant immunity - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
Phospholipase D (PLD) hydrolyzes membrane phospholipids to generate phosphatidic acid (PA). Both PLD and its lipid product PA are involved in various physiological processes, including plant response to pathogens. The PLD family is comprised of multiple members in higher plants, and PLDs have been reported to play positive and/or negative roles in plant immunity, depending on the types of pathogens and specific PLDs involved. Individual PLDs have distinguishable biochemical properties, such as Ca2+ and phosphatidylinositide requirements. In addition, PLDs and PA are found to interact with various proteins in hormone and stress signaling. The different biochemical and regulatory properties of PLDs and PA shed light on the mechanisms for the functional diversity of PLDs in plant defense signaling and response.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Frontiers | Nodulating Legumes Are Distinguished by a Sensitivity to Cytokinin in the Root Cortex Leading to Pseudonodule Development | Plant Science

Frontiers | Nodulating Legumes Are Distinguished by a Sensitivity to Cytokinin in the Root Cortex Leading to Pseudonodule Development | Plant Science | Plant immunity and legume symbiosis | Scoop.it
Root nodule symbiosis (RNS) is a feature confined to a single clade of plants, the Fabids. Among Fabids capable of RNS, legumes form root cortex-based nodules in symbioses with rhizobia, while actinorhizal species form lateral root-based nodules with actinomycetes. Cytokinin has previously been shown to be sufficient for “pseudonodule” initiation in model legumes. Here, we tested whether this response correlates with the ability to nodulate across a range of plant species. We analyzed the formation of pseudonodules in 17 nodulating and non-nodulating legume species, and 11 non-legumes, including nodulating actinorhizal species, using light and fluorescence microscopy. Cytokinin-induced pseudonodules arising from cortical cell divisions occurred in all nodulating legume species, but not in any of the other species, including non-nodulating legumes. Pseudonodule formation was dependent on the CRE1 cytokinin receptor in Medicago truncatula. Inhibition of root growth by cytokinin occurred across plant groups, indicating that pseudonodule development is the result of a specific cortical cytokinin response unique to nodulating legumes. Lack of a cortical cytokinin response from the Arabidopsis thaliana cytokinin reporter TCSn::GFP supported this hypothesis. Our results suggest that the ability to form cortical cell-derived nodules was gained in nodulating legumes, and likely lost in non-nodulating legumes, due to a specific root cortical response to cytokinin.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Frontiers | BAKing up to Survive a Battle: Functional Dynamics of BAK1 in Plant Programmed Cell Death | Plant Science

Frontiers | BAKing up to Survive a Battle: Functional Dynamics of BAK1 in Plant Programmed Cell Death | Plant Science | Plant immunity and legume symbiosis | Scoop.it
In plants, programmed cell death (PCD) has diverse, essential roles in vegetative and reproductive development, and in the responses to abiotic and biotic stresses. Despite the rapid progress in understanding the occurrence and functions of the diverse forms of PCD in plants, the signaling components and molecular mechanisms underlying the core PCD machinery remain a mystery. The roles of BAK1 (BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1), an essential co-receptor of multiple receptor complexes, in the regulation of immunity and development- and defense-related PCD have been well characterized. However, the ways in which BAK1 functions in mediating PCD need to be further explored. In this review, different forms of PCD in both plants and mammals are discussed. Moreover, we mainly summarize recent advances in elucidating the functions and possible mechanisms of BAK1 in controlling diverse forms of PCD. We also highlight the involvement of post-translational modifications (PTMs) of multiple signaling component proteins in BAK1-mediated PCD.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Plant Biology: Proteolytic Release of Damage Signals - ScienceDirect

Plant Biology: Proteolytic Release of Damage Signals - ScienceDirect | Plant immunity and legume symbiosis | Scoop.it
Plants protect their wounds against pathogen invasion by releasing damage signals that induce immune responses in neighboring cells. A new study shows that a conserved bioactive peptide is released from its cytoplasmic precursor upon wounding by a metacaspase that is activated by calcium influx into the injured cell.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Frontiers | Advanced Imaging for Quantitative Evaluation of Aphanomyces Root Rot Resistance in Lentil | Plant Science

Frontiers | Advanced Imaging for Quantitative Evaluation of Aphanomyces Root Rot Resistance in Lentil | Plant Science | Plant immunity and legume symbiosis | Scoop.it
Aphanomyces root rot (ARR) is a soil-borne disease that results in severe yield losses in lentil. The development of resistant cultivars is one of the key strategies to control this pathogen. However, the evaluation of disease severity is limited to visual scores that can be subjective. This study utilized image-based phenotyping approaches to evaluate Aphanomyces euteiches resistance in lentil genotypes in greenhouse (351 genotypes from lentil single plant/LSP derived collection and 191 genotypes from recombinant inbred lines/RIL using digital Red-Green-Blue/RGB and hyperspectral imaging) and field (173 RIL genotypes using unmanned aerial system-based multispectral imaging) conditions. Moderate to strong correlations were observed between RGB, multispectral, and hyperspectral derived features extracted from lentil shoots/roots and visual scores. In general, root features extracted from RGB imaging were found to be strongly associated with disease severity. With only three root traits, elastic net regression model was able to predict disease severity across and within multiple datasets (R2 = 0.45–0.73 and RMSE = 0.66–1.00). The selected features could represent visual disease scores. Moreover, we developed twelve normalized difference spectral indices (NDSIs) that were significantly correlated with disease scores: two NDSIs for lentil shoot section – computed from wavelengths of 1170, 1160, 1270, and 1280 nm (0.12 ≤ |r| ≤ 0.24, P < 0.05) and ten NDSIs for lentil root sections – computed from wavelengths in the range of 630–670, 700–840, and 1320–1530 nm (0.10 ≤ |r| ≤ 0.50, P < 0.05). Root-derived NDSIs were more accurate in predicting disease scores with an R2 of 0.54 (RMSE = 0.86), especially when the model was trained and tested on LSP accessions, compared to R2 of 0.25 (RMSE = 1.64) when LSP and RIL genotypes were used as train and test datasets, respectively. Importantly, NDSIs – computed from wavelengths of 700, 710, 730, and 790 nm – had strong positive correlations with disease scores (0.35 ≤r ≤ 0.50, P < 0.0001), which was confirmed in field phenotyping with similar correlations using vegetation index with red edge wavelength (normalized difference red edge, 0.36 ≤ |r| ≤ 0.57, P < 0.0001). The adopted image-based phenotyping approaches can help plant breeders to objectively quantify ARR resistance and reduce the subjectivity in selecting potential genotypes.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Receptor-Like Cytoplasmic Kinases: Central Players in Plant Receptor Kinase–Mediated Signaling | Annual Review of Plant Biology

Receptor-Like Cytoplasmic Kinases: Central Players in Plant Receptor Kinase–Mediated Signaling | Annual Review of Plant Biology | Plant immunity and legume symbiosis | Scoop.it
Receptor kinases (RKs) are of paramount importance in transmembrane signaling that governs plant reproduction, growth, development, and adaptation to diverse environmental conditions. Receptor-like cytoplasmic kinases (RLCKs), which lack extracellular ligand-binding domains, have emerged as a major class of signaling proteins that regulate plant cellular activities in response to biotic/abiotic stresses and endogenous extracellular signaling molecules. By associating with immune RKs, RLCKs regulate multiple downstream signaling nodes to orchestrate a complex array of defense responses against microbial pathogens. RLCKs also associate with RKs that perceive brassinosteroids and signaling peptides to coordinate growth, pollen tube guidance, embryonic and stomatal patterning, floral organ abscission, and abiotic stress responses. The activity and stability of RLCKs are dynamically regulated not only by RKs but also by other RLCK-associated proteins. Analyses of RLCK-associated components and substrates have suggested phosphorylation relays as a major mechanism underlying RK-mediated signaling.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

A Remote cis-Regulatory Region Is Required for NIN Expression in the Pericycle to Initiate Nodule Primordium Formation in Medicago truncatula

A Remote cis-Regulatory Region Is Required for NIN Expression in the Pericycle to Initiate Nodule Primordium Formation in Medicago truncatula | Plant immunity and legume symbiosis | Scoop.it
The legume-rhizobium symbiosis results in nitrogen-fixing root nodules, and their formation involves both intracellular infection initiated in the epidermis and nodule organogenesis initiated in inner root cell layers. NODULE INCEPTION (NIN) is a nodule-specific transcription factor essential for both processes. These NIN-regulated processes occur at different times and locations in the root, demonstrating a complex pattern of spatiotemporal regulation. We show that regulatory sequences sufficient for the epidermal infection process are located within a 5 kb region directly upstream of the NIN start codon in Medicago truncatula. Furthermore, we identify a remote upstream cis-regulatory region required for the expression of NIN in the pericycle, and we show that this region is essential for nodule organogenesis. This region contains putative cytokinin response elements and is conserved in eight more legume species. Both the cytokinin receptor 1, which is essential for nodule primordium formation, and the B-type response regulator RR1 are expressed in the pericycle in the susceptible zone of the uninoculated root. This, together with the identification of the cytokinin-responsive elements in the NIN promoter, strongly suggests that NIN expression is initially triggered by cytokinin signaling in the pericycle to initiate nodule primordium formation.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Molecular Dissection of Early Defense Signaling Underlying Volatile-Mediated Defense Regulation and Herbivore Resistance in Rice

Molecular Dissection of Early Defense Signaling Underlying Volatile-Mediated Defense Regulation and Herbivore Resistance in Rice | Plant immunity and legume symbiosis | Scoop.it
Herbivore-induced plant volatiles prime plant defenses and resistance, but how they are integrated into early defense signaling and whether a causal relationship exists between volatile defense priming and herbivore resistance is unclear. Here, we investigated the impact of indole, a common herbivore-induced plant volatile and modulator of many physiological processes in plants, bacteria, and animals, on early defense signaling and herbivore resistance in rice (Oryza sativa). Rice plants infested by fall armyworm (Spodoptera frugiperda) caterpillars release indole at a rate of up to 25 ng*h−1. Exposure to equal doses of exogenous indole enhances rice resistance to S. frugiperda. Screening of early signaling components revealed that indole pre-exposure directly enhances the expression of the leucine-rich repeat-receptor-like kinase OsLRR-RLK1. Pre-exposure to indole followed by simulated herbivory increases (i.e. primes) the transcription, accumulation, and activation of the mitogen-activated protein kinase OsMPK3 and the expression of the downstream WRKY transcription factor gene OsWRKY70 as well as several jasmonate biosynthesis genes, resulting in higher jasmonic acid (JA) accumulation. Analysis of transgenic plants defective in early signaling showed that OsMPK3 is required and that OsMPK6 and OsWRKY70 contribute to indole-mediated defense priming of JA-dependent herbivore resistance. Therefore, herbivore-induced plant volatiles increase plant resistance to herbivores by positively regulating early defense signaling components.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Nodule‐specific PLAT domain proteins are expanded in the Medicago lineage and required for nodulation - Trujillo - 2019 - New Phytologist -

Nodule‐specific PLAT domain proteins are expanded in the Medicago lineage and required for nodulation - Trujillo - 2019 - New Phytologist - | Plant immunity and legume symbiosis | Scoop.it
Symbiotic nitrogen fixation in legumes is mediated by an interplay of signaling processes between plant hosts and rhizobial symbionts. In legumes, several secreted protein families have undergone expansions and play key roles in nodulation. Thus, identifying lineage‐specific expansions (LSEs) of nodulation‐associated genes can be a strategy to discover candidate gene families.
Using bioinformatic tools, we identified 13 LSEs of nodulation‐related secreted protein families, each unique to either Glycine, Arachis or Medicago lineages. In the Medicago lineage, nodule‐specific Polycystin‐1, Lipoxygenase, Alpha Toxin (PLAT) domain proteins (NPDs) expanded to five members. We examined NPD function using CRISPR/Cas9 multiplex genome editing to create Medicago truncatula NPD knockout lines, targeting one to five NPD genes.
Mutant lines with differing combinations of NPD gene inactivations had progressively smaller nodules, earlier onset of nodule senescence, or ineffective nodules compared to the wild‐type control. Double‐ and triple‐knockout lines showed dissimilar nodulation phenotypes but coincided in upregulation of a DHHC‐type zinc finger and an aspartyl protease gene, possible candidates for the observed disturbance of proper nodule function.
By postulating that gene family expansions can be used to detect candidate genes, we identified a family of nodule‐specific PLAT domain proteins and confirmed that they play a role in successful nodule formation.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Exploring the protein–protein interaction landscape in plants - Struk - 2019 - Plant, Cell & Environment -

Exploring the protein–protein interaction landscape in plants - Struk - 2019 - Plant, Cell & Environment - | Plant immunity and legume symbiosis | Scoop.it
Protein–protein interactions (PPIs) represent an essential aspect of plant systems biology. Identification of key protein players and their interaction networks provide crucial insights into the regulation of plant developmental processes and into interactions of plants with their environment. Despite the great advance in the methods for the discovery and validation of PPIs, still several challenges remain. First, the PPI networks are usually highly dynamic, and the in vivo interactions are often transient and difficult to detect. Therefore, the properties of the PPIs under study need to be considered to select the most suitable technique, because each has its own advantages and limitations. Second, besides knowledge on the interacting partners of a protein of interest, characteristics of the interaction, such as the spatial or temporal dynamics, are highly important. Hence, multiple approaches have to be combined to obtain a comprehensive view on the PPI network present in a cell. Here, we present the progress in commonly used methods to detect and validate PPIs in plants with a special emphasis on the PPI features assessed in each approach and how they were or can be used for the study of plant interactions with their environment.
No comment yet.
Scooped by Christophe Jacquet
Scoop.it!

Hydrogen peroxide metabolism and functions in plants - Smirnoff - 2019 - New Phytologist -

Hydrogen peroxide metabolism and functions in plants - Smirnoff - 2019 - New Phytologist - | Plant immunity and legume symbiosis | Scoop.it
Hydrogen peroxide (H2O2) is produced, via superoxide and superoxide dismutase, by electron transport in chloroplasts and mitochondria, plasma membrane NADPH oxidases, peroxisomal oxidases, type III peroxidases and other apoplastic oxidases. Intracellular transport is facilitated by aquaporins and H2O2 is removed by catalase, peroxiredoxin, glutathione peroxidase‐like enzymes and ascorbate peroxidase, all of which have cell compartment‐specific isoforms. Apoplastic H2O2 influences cell expansion, development and defence by its involvement in type III peroxidase‐mediated polymer cross‐linking, lignification and, possibly, cell expansion via H2O2‐derived hydroxyl radicals. Excess H2O2 triggers chloroplast and peroxisome autophagy and programmed cell death. The role of H2O2 in signalling, for example during acclimation to stress and pathogen defence, has received much attention, but the signal transduction mechanisms are poorly defined. H2O2 oxidizes specific cysteine residues of target proteins to the sulfenic acid form and, similar to other organisms, this modification could initiate thiol‐based redox relays and modify target enzymes, receptor kinases and transcription factors. Quantification of the sources and sinks of H2O2 is being improved by the spatial and temporal resolution of genetically encoded H2O2 sensors, such as HyPer and roGFP2‐Orp1. These H2O2 sensors, combined with the detection of specific proteins modified by H2O2, will allow a deeper understanding of its signalling roles.
No comment yet.