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Telegraph: British scientists appeal to world for Ash dieback help (2012)

Telegraph: British scientists appeal to world for Ash dieback help (2012) | Plants and Microbes | Scoop.it
British scientists have made a global appeal for help finding weaknesses in the fungus causing ash dieback after publishing the first molecular sequencing data on the disease.

Using information on the fungus's RNA – the sister molecule of DNA which helps regulate the behaviour of genes – researchers hope to discover how the fungus causes disease, and how it can be stopped. Scientists from the Sainsbury Laboratory and the John Innes Centre examined a sample of pith from a twig of an infected Ash tree in Ashwellthorpe wood in Norfolk, the first natural environment where the fungus was found in the UK. From the sample they extracted RNA and sequenced it to help them identify which genes are most influential in allowing the fungus to spread between trees so quickly. In normal circumstances, scientists would analyse the sample thoroughly and have their findings peer-reviewed before publishing them in a journal. But because of the urgency of the situation, the researchers took the unusual step of publishing their data online and asking experts from around the world to help them produce accurate results more quickly through "crowdsourcing".
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PNAS: Herbivore exploits orally secreted bacteria to suppress plant defenses (2013)

PNAS: Herbivore exploits orally secreted bacteria to suppress plant defenses (2013) | Plants and Microbes | Scoop.it

The role of herbivore-associated microbes in modifying plant defenses has received scant attention. The Colorado potato beetle secretes symbiotic bacteria to wounds to manipulate plant defenses. The bacteria elicit salicylic acid (SA)-regulated defenses, and because SA signaling often negatively cross-talks with jasmonate signaling, plants are unable to fully activate their jasmonate-mediated resistance against the herbivore. From the plants’ perspective, they recognize herbivores not as such, but as microbial threats. We identified the specific bacteria from the beetle secretions and also characterized one of the bacterial effectors responsible for defense suppression. This clever, deceptive strategy for suppressing defenses has not been previously documented. Our results add a significant, unique concept to plant–insect interactions and how herbivores hijack plant defense signaling.

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Frontiers: The past, present and future of breeding rust resistant wheat (2014)

Frontiers: The past, present and future of breeding rust resistant wheat (2014) | Plants and Microbes | Scoop.it

Two classes of genes are used for breeding rust resistant wheat. The first class, called R (for resistance) genes, are pathogen race-specific in their action, effective at all plant growth stages and probably mostly encode immune receptors of the nucleotide binding leucine rich repeat (NB-LRR) class. The second class called Adult Plant Resistance genes (APR) because resistance is usually functional only in adult plants, and, in contrast to most R genes, the levels of resistance conferred by single APR genes are only partial and allow considerable disease development. Some but not all APR genes provide resistance to all isolates of a rust pathogen species and a subclass of these provides resistance to several fungal pathogen species. Initial indications are that APR genes encode a more heterogeneous range of proteins than R proteins. Two APR genes, Lr34 and Yr36, have been cloned from wheat and their products are an ABC transporter and a protein kinase, respectively. Lr34 and Sr2 have provided long lasting and widely used (durable) partial resistance and are mainly used in conjunction with other R and APR genes to obtain adequate rust resistance. We caution that some APR genes indeed include race-specific, weak R genes which may be of the NB-LRR class. A research priority to better inform rust resistance breeding is to characterize further APR genes in wheat and to understand how they function and how they interact when multiple APR and R genes are stacked in a single genotype by conventional and GM breeding. An important message is do not be complacent about the general durability of all APR genes.

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Nature Reviews Genetics: Microbial genome-enabled insights into plant-microorganism interactions (2014)

Nature Reviews Genetics: Microbial genome-enabled insights into plant-microorganism interactions (2014) | Plants and Microbes | Scoop.it

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

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PLOS Genetics: The Nuclear Immune Receptor RPS4 Is Required for RRS1SLH1-Dependent Constitutive Defense Activation in Arabidopsis thaliana (2014)

PLOS Genetics: The Nuclear Immune Receptor RPS4 Is Required for RRS1SLH1-Dependent Constitutive Defense Activation in Arabidopsis thaliana (2014) | Plants and Microbes | Scoop.it

Plant nucleotide-binding leucine-rich repeat (NB-LRR) disease resistance (R) proteins recognize specific “avirulent” pathogen effectors and activate immune responses. NB-LRR proteins structurally and functionally resemble mammalian Nod-like receptors (NLRs). How NB-LRR and NLR proteins activate defense is poorly understood. The divergently transcribed Arabidopsis R genes, RPS4 (resistance to Pseudomonas syringae 4) and RRS1 (resistance to Ralstonia solanacearum 1), function together to confer recognition of PseudomonasAvrRps4 and Ralstonia PopP2. RRS1 is the only known recessive NB-LRR R gene and encodes a WRKY DNA binding domain, prompting suggestions that it acts downstream of RPS4 for transcriptional activation of defense genes. We define here the early RRS1-dependent transcriptional changes upon delivery of PopP2 via Pseudomonas type III secretion. The Arabidopsis slh1 (sensitive to low humidity 1) mutant encodes an RRS1 allele (RRS1SLH1) with a single amino acid (leucine) insertion in the WRKY DNA-binding domain. Its poor growth due to constitutive defense activation is rescued at higher temperature. Transcription profiling data indicate that RRS1SLH1-mediated defense activation overlaps substantially with AvrRps4- and PopP2-regulated responses. To better understand the genetic basis of RPS4/RRS1-dependent immunity, we performed a genetic screen to identify suppressor of slhimmunity (sushi) mutants. We show that many sushi mutants carry mutations in RPS4, suggesting that RPS4 acts downstream or in a complex with RRS1. Interestingly, several mutations were identified in a domain C-terminal to the RPS4 LRR domain. Using an Agrobacterium-mediated transient assay system, we demonstrate that the P-loop motif of RPS4 but not of RRS1SLH1 is required for RRS1SLH1 function. We also recapitulate the dominant suppression of RRS1SLH1 defense activation by wild type RRS1 and show this suppression requires an intact RRS1 P-loop. These analyses of RRS1SLH1shed new light on mechanisms by which NB-LRR protein pairs activate defense signaling, or are held inactive in the absence of a pathogen effector.

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PLOS One: Seed Transmission of Pseudoperonospora cubensis (2014)

PLOS One: Seed Transmission of Pseudoperonospora cubensis (2014) | Plants and Microbes | Scoop.it

Pseudoperonospora cubensis, an obligate biotrophic oomycete causing devastating foliar disease in species of the Cucurbitaceae family, was never reported in seeds or transmitted by seeds. We now show that P. cubensis occurs in fruits and seeds of downy mildew-infected plants but not in fruits or seeds of healthy plants. About 6.7% of the fruits collected during 2012–2014 have developed downy mildew when homogenized and inoculated onto detached leaves and 0.9% of the seeds collected developed downy mildew when grown to the seedling stage. This is the first report showing that P. cubensis has become seed-transmitted in cucurbits. Species-specific PCR assays showed that P. cubensis occurs in ovaries, fruit seed cavity and seed embryos of cucurbits. We propose that international trade of fruits or seeds of cucurbits might be associated with the recent global change in the population structure of P. cubensis.

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Workshop: Genomics Research on Plant-Parasite Interactions to Increase Food Production UK-Mexico, 3-6 February 2015

Workshop: Genomics Research on Plant-Parasite Interactions to Increase Food Production UK-Mexico, 3-6 February 2015 | Plants and Microbes | Scoop.it

The British Council and the Mexican National Council of Science and Technology (CONACyT) have launched the programme 'Researcher Links' to encourage international research collaboration between young researchers from the UK and Mexico.


We are now inviting Early Career Researchers from the UK and Mexico to apply to attend this binational workshop on Genomics Research on Plant-Parasite Interactions to Increase Food Production that will take place in the city of Leon in the state of Guanajuato, Mexico.


All travel and accommodation expenses will be covered by the Researcher Links programme.

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British Council: Researcher Links workshop in Thailand on plant pathology, - 16-19 February 2015

British Council: Researcher Links workshop in Thailand on plant pathology, - 16-19 February 2015 | Plants and Microbes | Scoop.it

ABOUT THIS OPPORTUNITY


We have grants for early career researchers to attend a workshop entitled 'Plant-microbe interactions: pathogen and host diversity, infection and defense mechanisms and disease protection'. All travel, accommodation and meals will be covered.

Under the Researcher Links scheme offered within the Newton Fund, the British Council and the Thailand Research Fund will be holding a workshop on the above theme in Bangkok, Thailand on 16 – 19 February 2015. The workshop is being coordinated by Drs. Chatchawan Jantasuriyarat and Sophien Kamoun, and will have contributions from other leading researchers. The theme of the workshop is plant-pathogen interactions with an emphasis on studies of pathogen and host diversity, infection and defense mechanisms, as well as disease protection.


KEY DATES


Dates of workshop - 16-19 February 2015

Deadline for applications - 31 October 2014


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Cell Host & Microbe: A Plant Phosphoswitch Platform Repeatedly Targeted by Type III Effector Proteins Regulates the Output of Both Tiers of Plant Immune Receptors (2014)

Cell Host & Microbe: A Plant Phosphoswitch Platform Repeatedly Targeted by Type III Effector Proteins Regulates the Output of Both Tiers of Plant Immune Receptors (2014) | Plants and Microbes | Scoop.it

Plants detect microbes via two functionally interconnected tiers of immune receptors. Immune detection is suppressed by equally complex pathogen mechanisms. The small plasma-membrane-tethered protein RIN4 negatively regulates microbe-associated molecular pattern (MAMP)-triggered responses, which are derepressed upon bacterial flagellin perception. We demonstrate that recognition of the flagellin peptide MAMP flg22 triggers accumulation of RIN4 phosphorylated at serine 141 (pS141) that mediates derepression of several immune outputs. RIN4 is targeted by four bacterial type III effector proteins, delivered temporally after flagellin perception. Of these, AvrB acts with a host kinase to increase levels of RIN4 phosphorylated at threonine 166 (pT166). RIN4 pT166 is epistatic to RIN4 pS141. Thus, AvrB contributes to virulence by enhancing “rerepression” of immune system outputs. Our results explain the evolution of independent effectors that antagonize accumulation of RIN4 pS141 and of a specific plant intracellular NLR protein, RPM1, which is activated by AvrB-mediated accumulation of RIN4 pT166.

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Fungal Genetics and Biology: The Podosphaera xanthii haustorium, the fungal Trojan horse of cucurbit-powdery mildew interactions (2014)

Fungal Genetics and Biology: The Podosphaera xanthii haustorium, the fungal Trojan horse of cucurbit-powdery mildew interactions (2014) | Plants and Microbes | Scoop.it

The powdery mildew fungi are obligate biotrophic plant pathogens that develop a specialized structure for parasitism termed haustorium, which is responsible for nutrient uptake and factor exchange with the plant. In this work, we present a detailed microscopy analysis of the haustoria of the cucurbit powdery mildew fungus Podosphaera xanthii, a major limiting factor for cucurbit production worldwide. Despite being located inside plant epidermal cells, transmission electron microscopy (TEM) analysis showed the characteristic highly irregular outline of the extrahaustorial membrane that separates the extrahaustorial matrix of haustoria from the cytoplasm of the plant cell. TEM analysis also revealed the presence of some vesicles and electron-dense plaques of material surrounding the haustoria. In confocal microscopy analysis and aniline blue staining we found a positive correlation between haustorial development and deposition of callose, which is distributed as plaques around haustorial complex. In this study, a method for the isolation of P. xanthii haustoria was also adapted, which permitted the analysis of the formation of haustorial lobes and the visualization of vacuoles and the pool of vesicles inside the haustorial complex. Our findings suggested that the haustorial lobes were responsible for vesicular trafficking and most likely act as the main mediators of the fungus-plant dialogue. All of these findings were integrated into a model of the P. xanthii-host cellular interactions.

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Plant Journal: Probing formation of cargo/importin-α transport complexes in plant cells using a pathogen effector (2014)

Plant Journal: Probing formation of cargo/importin-α transport complexes in plant cells using a pathogen effector (2014) | Plants and Microbes | Scoop.it

Importin-αs are essential adapter proteins that recruit cytoplasmic proteins destined for active nuclear import to the nuclear transport machinery. Cargo proteins interact with the importin-α armadillo repeat domain via nuclear localization sequences (NLSs), short amino acids motifs enriched in Lys and Arg residues. Plant genomes typically encode several importin-α paralogs that can have both specific and partially redundant functions. Although some cargos are preferentially imported by a distinct importin-α, it remains unknown how this specificity is generated and to what extent cargos compete for binding to nuclear transport receptors. Here we report that the effector protein HaRxL106 from the oomycete pathogen Hyaloperonospora arabidopsidis co-opts the host cell's nuclear import machinery. We use HaRxL106 as a probe to determine redundant and specific functions of importin-α paralogs from Arabidopsis thaliana. A crystal structure of the importin-α3/MOS6 armadillo repeat domain suggests that five of the six Arabidopsis importin-αs expressed in rosette leaves have an almost identical NLS binding site. Comparison of the importin-α binding affinities of HaRxL106 and other cargos in vitro and in plant cells suggests that relatively small affinity differences in vitro affect the rate of transport complex formation in vivo. Our results suggest that cargo affinity for importin-α, sequence variation at the importin-α NLS binding sites and tissue-specific expression levels of importin-αs determine formation of cargo/importin-α transport complexes in plant cells.


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The Sainsbury Lab's curator insight, October 7, 4:34 AM

Importin-αs are essential adapter proteins that recruit cytoplasmic proteins destined for active nuclear import to the nuclear transport machinery. Cargo proteins interact with the importin-α armadillo repeat domain via nuclear localization sequences (NLSs), short amino acids motifs enriched in Lys and Arg residues. Plant genomes typically encode several importin-α paralogs that can have both specific and partially redundant functions. Although some cargos are preferentially imported by a distinct importin-α, it remains unknown how this specificity is generated and to what extent cargos compete for binding to nuclear transport receptors. Here we report that the effector protein HaRxL106 from the oomycete pathogen Hyaloperonospora arabidopsidis co-opts the host cell's nuclear import machinery. We use HaRxL106 as a probe to determine redundant and specific functions of importin-α paralogs from Arabidopsis thaliana. A crystal structure of the importin-α3/MOS6 armadillo repeat domain suggests that five of the six Arabidopsis importin-αs expressed in rosette leaves have an almost identical NLS binding site. Comparison of the importin-α binding affinities of HaRxL106 and other cargos in vitro and in plant cells suggests that relatively small affinity differences in vitro affect the rate of transport complex formation in vivo. Our results suggest that cargo affinity for importin-α, sequence variation at the importin-α NLS binding sites and tissue-specific expression levels of importin-αs determine formation of cargo/importin-α transport complexes in plant cells.

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Plant J: Deep sequencing of the ancestral tobacco species Nicotiana tomentosiformis reveals multiple T-DNA inserts and a complex evolutionary history of natural transformation in the genus Nicotian...

Plant J: Deep sequencing of the ancestral tobacco species Nicotiana tomentosiformis reveals multiple T-DNA inserts and a complex evolutionary history of natural transformation in the genus Nicotian... | Plants and Microbes | Scoop.it

Nicotiana species carry cellular T-DNA sequences (cT-DNAs), acquired by Agrobacterium-mediated transformation. We characterized the cT-DNA sequences of the ancestral N. tabacum species N. tomentosiformis by deep sequencing. N. tomentosiformis contains four cT-DNA inserts derived from different Agrobacterium strains. Each has an incomplete inverted repeat structure. TA is similar to part of the A. rhizogenes 1724 mikimopine-type T-DNA, but has unusual orf14 and mis genes. TB carries a 1724 mikimopine-type orf14-mis fragment and a mannopine-agropine synthesis region (mas2’-mas1’-ags). The mas2’ gene codes for an active enzyme. TC is similar to the left part of the A. rhizogenes A4 T-DNA but also carries octopine synthase-like (ocl) and c-like genes normally found in A. tumefaciens. TD shows a complex rearrangement of T-DNA fragments similar to the right end of the A4 TL-DNA, and including an orf14-like gene and a gene with unknown function, orf511. The TA, TB, TC and TD insertion sites were identified by alignment to N. tabacum and N. sylvestris sequences. The divergence values for the TA, TB, TC and TD repeats provide an estimate for their relative introduction times. A large deletion has occurred in the central part of the N. tabacum cv. Basma/Xanthi TA region, another one removed the complete TC region in N. tabacum. N. otophora lacks TA, TB and TD, but contains TC and another cT-DNA, TE. This analysis, together with that of N. glauca and other Nicotiana species, indicates multiple sequential insertions of cT-DNAs during the evolution of the genus Nicotiana.

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The Scientist: Opinion: The Planet Needs More Plant Scientists (2014)

The Scientist: Opinion: The Planet Needs More Plant Scientists (2014) | Plants and Microbes | Scoop.it

Academia is not producing sufficient PhDs in the plant sciences to solve the crop production challenges facing a rapidly growing population.

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Peter Buckland's curator insight, October 2, 6:34 AM

Yet more evidence of the decline in plant sciences

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New Phytologist: Special Issue: Plants interacting with other organisms (October 2014)

New Phytologist: Special Issue: Plants interacting with other organisms (October 2014) | Plants and Microbes | Scoop.it

Editorial


Plant interactions with other organisms: molecules, ecology and evolution


Commentary


Different shades of JAZ during plant growth and defense


Nutrient supply differentially alters the dynamics of co-infecting phytoviruses


Letters


From shade avoidance responses to plant performance at vegetation level: using virtual plant modelling as a tool
F. J. Bongers, J. B. Evers, N. P. R. Anten & R. Pierik


Review


Magical mystery tour: MLO proteins in plant immunity and beyond
J. Acevedo-Garcia, S. Kusch & R. Panstruga


The squeeze cell hypothesis for the activation of jasmonate synthesis in response to wounding

E. E. Farmer, D. Gasperini & I. F. Acosta


Lipochitooligosaccharide recognition: an ancient story
Y. Liang, K. Tóth, Y. Cao, K. Tanaka, C. Espinoza & G. Stacey


Herbivore-induced plant volatiles: targets, perception and unanswered questions
M. Heil


There’s no place like home? An exploration of the mechanisms behind plant litter–decomposer affinity in terrestrial ecosystems
A. T. Austin, L. Vivanco, A. González-Arzac & L. I. Pérez


Insect herbivore-associated organisms affect plant responses to herbivory
F. Zhu, E. H. Poelman & M. Dicke


When mutualism goes bad: density- dependent impacts of introduced bees on plant reproduction
M. A. Aizen, C. L. Morales, D. P. Vázquez, L. A. Garibaldi, A. Sáez & L. D. Harder


Insect and pathogen attack and resistance in maize and its wild ancestors, the teosintes
E. S. de Lange, D. Balmer, B. Mauch-Mani & T. C. J. Turlings


Full papers


Linking phytochrome to plant immunity: low red : far-red ratios increase Arabidopsis susceptibility to Botrytis cinerea by reducing the biosynthesis of indolic glucosinolates and camalexin
M. D. Cargnel, P. V. Demkura & C. L. Ballaré


To grow or defend? Low red : far-red ratios reduce jasmonate sensitivity in Arabidopsis seedlings by promoting DELLA degradation and increasing JAZ10 stability
M. Leone, M. M. Keller, I. Cerrudo & C. L. Ballaré


β-Glucosidase BGLU42 is a MYB72-dependent key regulator of rhizobacteria-induced systemic resistance and modulates iron deficiency responses in Arabidopsis roots
C. Zamioudis, J. Hanson & C. M. J. Pieterse


Deciphering the language of plant communication: volatile chemotypes of sagebrush
R. Karban, W. C. Wetzel, K. Shiojiri, S. Ishizaki, S. R. Ramirez & J. D. Blande


The context dependence of beneficiary feedback effects on benefactors in plant facilitation
C. Schöb, R. M. Callaway, F. Anthelme, R. W. Brooker, L. A. Cavieres, Z. Kikvidze, C. J. Lortie, R. Michalet, F. I. Pugnaire, S. Xiao, B. H. Cranston, M-C. García, N. R. Hupp, L. D. Llambí, E. Lingua, A. M. Reid, L. Zhao & B. J. Butterfield


Herbivore-mediated material fluxes in a northern deciduous forest under elevated carbon dioxide and ozone concentrations
T. D. Meehan, J. J. Couture, A. E. Bennett & R. L. Lindroth


Are plant–soil feedback responses explained by plant traits?
C. Baxendale, K. H. Orwin, F. Poly, T. Pommier & R. D. Bardgett


Environmental nutrient supply alters prevalence and weakens competitive interactions among coinfecting viruses
C. Lacroix, E. W. Seabloom & E. T. Borer

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PRISM - The Philippine Rice Information System (2014)

PRISM - The Philippine Rice Information System (2014) | Plants and Microbes | Scoop.it

The Philippine Rice Information System (PRISM) is an operational system for monitoring rice. It supports decision making and activity planning for increased rice production in the Philippines, and has nationwide coverage to help improve food security. It also serves as a platform to develop consistent and regular assessments of rice crop production, crop health, and crop losses due to natural calamities such as floods, droughts, and outbreaks of pests and diseases.

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Frontiers: A novel conserved mechanism for plant NLR protein pairs: the ‘integrated decoy’ hypothesis (2014)

Frontiers: A novel conserved mechanism for plant NLR protein pairs: the ‘integrated decoy’ hypothesis (2014) | Plants and Microbes | Scoop.it

Plant immunity is often triggered by the specific recognition of pathogen effectors by intracellular nucleotide-binding, leucine-rich repeat (NLR) receptors. Plant NLRs contain an N-terminal signaling domain that is mostly represented by either a Toll-interleukin1 receptor (TIR) domain or a coiled coil (CC) domain. In many cases, single NLR proteins are sufficient for both effector recognition and signaling activation. However, many paired NLRs have now been identified where both proteins are required to confer resistance to pathogens. Recent detailed studies on the Arabidopsis thaliana TIR-NLR pair RRS1 and RPS4 and on the rice CC-NLR pair RGA4 and RGA5 have revealed for the first time how such protein pairs function together. In both cases, the paired partners interact physically to form a hetero-complex receptor in which each partner plays distinct roles in effector recognition or signaling activation, highlighting a conserved mode of action of NLR pairs across both monocotyledonous and dicotyledonous plants. We also discuss a new ‘integrated decoy’ effector recognition model to describe these receptor complexes that may be common to many other plant NLR pairs.

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Elsa Ballini's curator insight, October 29, 4:21 AM

In Rice/Magnaporthe an example is RGA4-RGA5

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PlantVillage: Rice blast disease: hopes for control (2014)

PlantVillage: Rice blast disease: hopes for control (2014) | Plants and Microbes | Scoop.it

Readers of PlantVillage (www.plantvillage.com) will be well aware of the devastation that plant diseases can cause, whether they are affecting garden produce or agricultural fields, the symptoms of plant diseases are very obvious from blights and rusts, to moulds and mildews.


The devastation reeked by plant pathogens also makes a huge impact on the ability of the world to feed itself. It has recently been estimated that losses due to plant pathogens are one of the most significant constraints on worldwide food production. Indeed, it has been estimated that if normal, low-level plant diseases could be effectively controlled, this would allow food production sufficient to feed 8.5% of the current human population (almost 600 million people). Therefore to ensure global food security, we will require more durable means of controlling plant diseases, and we have to do that in a more sustainable way that is less heavily dependent on fossil fuels, and does not adversely affect the environment, including human health. This is a big challenge and will take considerably greater understanding of plant diseases and the pathogens that cause them.


Continue reading at http://medium.com/@plantvillage/rice-blast-disease-hopes-for-control-910655049d10

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eLife: The kinase LYK5 is a major chitin receptor in Arabidopsis and forms a chitin-induced complex with related kinase CERK1 (2014)

eLife: The kinase LYK5 is a major chitin receptor in Arabidopsis and forms a chitin-induced complex with related kinase CERK1 (2014) | Plants and Microbes | Scoop.it

Chitin is a fungal microbe-associated molecular pattern (MAMP) that is recognized in Arabidopsis by a lysin motif receptor kinase (LYK), AtCERK1. Previous research suggested that AtCERK1 is the major chitin receptor in plants and mediates chitin-induced signaling through homodimerization and phosphorylation. However, the reported chitin binding affinity of AtCERK1 is quite low, suggesting another receptor with high chitin binding affinity might be present. Here, we propose that AtLYK5 is the primary chitin receptor in Arabidopsis. Mutations in AtLYK5 resulted in a significant reduction in the plant chitin response. However, AtLYK5 shares overlapping function with AtLYK4 and, therefore, only AtLYK4/AtLYK5-2 double mutants show a complete loss of chitin response. AtLYK5 interacts with AtCERK1 in a chitin-dependent manner. Chitin binding to AtLYK5 is indispensable for chitin-induced AtCERK1 phosphorylation. AtLYK5 binds chitin at a higher affinity than AtCERK1. The data suggest that AtLYK5 is the primary receptor for chitin to induce plant immunity.

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Jean-Michel Ané's curator insight, October 24, 12:06 PM

A must read if you are interested in Nod and Myc factor receptors too...

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Frontiers in Legume Biology - The second Adam Kondorosi Symposium, 11-12 December 2014, Gif-sur-Yvette (France)

Frontiers in Legume Biology - The second Adam Kondorosi Symposium, 11-12 December 2014, Gif-sur-Yvette (France) | Plants and Microbes | Scoop.it

The objective of this symposium is to create a scientific event that is at the forefront of fundamental research in diverse aspects of legume biology.


The meeting will be divided into 5 sessions:
1) Symbiosis; 2) Genomics; 3) Pathogenesis; 4) Physiology and stress responses; 5) Development


The symposium will bring together about 150 participants in a rather informal atmosphere, facilitating exchanges. We also aim at proposing a highly attractive program at a moderate inscription fee to give the opportunity to researchers - in particular those at the early stage of their career – to participate to an exciting top-level scientific event. Young researchers will have the opportunity to present their work with a poster.

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David Kuykendall's curator insight, October 28, 9:11 AM

This honors Adam Kondorosi and he was one of the greats.

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PLOS Pathogens: Expression Profiling during Arabidopsis/Downy Mildew Interaction Reveals a Highly-Expressed Effector That Attenuates Responses to Salicylic Acid (2014)

PLOS Pathogens: Expression Profiling during Arabidopsis/Downy Mildew Interaction Reveals a Highly-Expressed Effector That Attenuates Responses to Salicylic Acid (2014) | Plants and Microbes | Scoop.it

Plants have evolved strong innate immunity mechanisms, but successful pathogens evade or suppress plant immunity via effectors delivered into the plant cell. Hyaloperonospora arabidopsidis (Hpa) causes downy mildew on Arabidopsis thaliana, and a genome sequence is available for isolate Emoy2. Here, we exploit the availability of genome sequences for Hpa and Arabidopsis to measure gene-expression changes in both Hpa and Arabidopsis simultaneously during infection. Using a high-throughput cDNA tag sequencing method, we reveal expression patterns of Hpa predicted effectors and Arabidopsis genes in compatible and incompatible interactions, and promoter elements associated with Hpa genes expressed during infection. By resequencing Hpa isolate Waco9, we found it evades Arabidopsis resistance gene RPP1through deletion of the cognate recognized effector ATR1. Arabidopsis salicylic acid (SA)-responsive genes including PR1 were activated not only at early time points in the incompatible interaction but also at late time points in the compatible interaction. By histochemical analysis, we found that Hpa suppresses SA-inducible PR1 expression, specifically in the haustoriated cells into which host-translocated effectors are delivered, but not in non-haustoriated adjacent cells. Finally, we found a highly-expressed Hpa effector candidate that suppresses responsiveness to SA. As this approach can be easily applied to host-pathogen interactions for which both host and pathogen genome sequences are available, this work opens the door towards transcriptome studies in infection biology that should help unravel pathogen infection strategies and the mechanisms by which host defense responses are overcome.

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Cell Host & Microbe: Proline Isomerization of the Immune Receptor-Interacting Protein RIN4 by a Cyclophilin Inhibits Effector-Triggered Immunity in Arabidopsis (2014)

Cell Host & Microbe: Proline Isomerization of the Immune Receptor-Interacting Protein RIN4 by a Cyclophilin Inhibits Effector-Triggered Immunity in Arabidopsis (2014) | Plants and Microbes | Scoop.it

In the absence of pathogen infection, plant effector-triggered immune (ETI) receptors are maintained in a preactivation state by intermolecular interactions with other host proteins. Pathogen effector-induced alterations activate the receptor. In Arabidopsis, the ETI receptor RPM1 is activated via bacterial effector AvrB-induced phosphorylation of the RPM1-interacting protein RIN4 at Threonine 166. We find that RIN4 also interacts with the prolyl-peptidyl isomerase (PPIase) ROC1, which is reduced upon RIN4 Thr166 phosphorylation. ROC1 suppresses RPM1 immunity in a PPIase-dependent manner. Consistent with this, RIN4 Pro149 undergoes cis/transisomerization in the presence of ROC1. While the RIN4P149V mutation abolishes RPM1 resistance, the deletion of Pro149 leads to RPM1 activation in the absence of RIN4 phosphorylation. These results support a model in which RPM1 directly senses conformational changes in RIN4 surrounding Pro149 that is controlled by ROC1. RIN4 Thr166 phosphorylation indirectly regulates RPM1 resistance by modulating the ROC1-mediated RIN4 isomerization.

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bioRxiv: A putative antiviral role of plant cytidine deaminases (2014)

bioRxiv: A putative antiviral role of plant cytidine deaminases (2014) | Plants and Microbes | Scoop.it

A mechanism of innate antiviral immunity operating against viruses infecting mammalian cells has been described during the last decade. Host cytidine deaminases (e.g., APOBEC3 proteins) edit viral genomes giving raise to hypermutated nonfunctional viruses; consequently, viral fitness is reduced through lethal mutagenesis. By contrast, sub-lethal hypermutagenesis may contribute to virus evolvability by increasing population diversity. To prevent genome editing, some viruses have evolved proteins that mediate APOBEC3 degradation. The model plant Arabidopsis thaliana encodes for nine cytidine deaminases (AtCDAs), raising the question of whether deamination is an antiviral mechanism in plants as well. Here we tested the effects of AtCDAs expression on the pararetrovirus Cauliflower mosaic virus (CaMV). We show that A. thaliana AtCDA1 gene product exerts a mutagenic activity, which indeed generates a negative correlation between the level of AtCDA1 expression and CaMV accumulation in the plant, suggesting that deamination may also work as an antiviral mechanism in plants.

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Nature Communications: Long-distance endosome trafficking drives fungal effector production during plant infection (2014)

Nature Communications: Long-distance endosome trafficking drives fungal effector production during plant infection (2014) | Plants and Microbes | Scoop.it

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

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PNAS: A receptor-like protein mediates the response to pectin modification by activating brassinosteroid signaling (2014)

PNAS: A receptor-like protein mediates the response to pectin modification by activating brassinosteroid signaling (2014) | Plants and Microbes | Scoop.it

Plant growth and development depend on the biosynthesis and remodeling of the cell wall. To coordinate these two processes, surveillance mechanisms have evolved to monitor the state of the cell wall. The brassinosteroid (BR) hormone signaling pathway plays an essential role in growth control and regulates the expression of a plethora of cell wall-related genes. We have previously shown that feedback signaling from the wall can modulate the outputs of the BR pathway, ensuring cell wall homeostasis and integrity. Here, we identified a receptor-like protein (RLP44), which mediates the activation of BR signaling through direct interaction with the BR coreceptor BAK1. Thus, RLP44 integrates cell wall surveillance with hormone signaling to control cell wall integrity and growth.


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The Sainsbury Lab's curator insight, October 7, 4:18 AM

Plant growth and development depend on the biosynthesis and remodeling of the cell wall. To coordinate these two processes, surveillance mechanisms have evolved to monitor the state of the cell wall. The brassinosteroid (BR) hormone signaling pathway plays an essential role in growth control and regulates the expression of a plethora of cell wall-related genes. We have previously shown that feedback signaling from the wall can modulate the outputs of the BR pathway, ensuring cell wall homeostasis and integrity. Here, we identified a receptor-like protein (RLP44), which mediates the activation of BR signaling through direct interaction with the BR coreceptor BAK1. Thus, RLP44 integrates cell wall surveillance with hormone signaling to control cell wall integrity and growth.

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PLOS Pathogens: Adaptive Prediction As a Strategy in Microbial Infections (2014)

PLOS Pathogens: Adaptive Prediction As a Strategy in Microbial Infections (2014) | Plants and Microbes | Scoop.it

Microorganisms need to sense and respond to constantly changing microenvironments, and adapt their transcriptome, proteome, and metabolism accordingly to survive [1]. However, microbes sometimes react in a way which does not make immediate biological sense in light of the current environment—for example, by up-regulating an iron acquisition system in times of metal abundance. The reason for this seemingly nonsensical behavior can lie in the microbe's ability to predict a coming change in conditions by cues from the current environment. If the microbe (pre-)adapts accordingly, it will increase its fitness and chances of survival under subsequent selection pressures—a concept known as adaptive prediction.

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Donald Danforth Plant Science Center’s 16th annual Fall Symposium: Macroinfluence of Microogranisms: Host-Microbe Interactions and Inspired Technologies (September 2014)

Donald Danforth Plant Science Center’s 16th annual Fall Symposium: Macroinfluence of Microogranisms: Host-Microbe Interactions and Inspired Technologies (September 2014) | Plants and Microbes | Scoop.it
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