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Rescooped by Gigy Varghese from Plants and Microbes
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Book: Plant-Pathogen Interactions: Methods and Protocols (2014)

Book: Plant-Pathogen Interactions: Methods and Protocols (2014) | plant microbial interaction | Scoop.it

Plant-Pathogen Interactions: Methods and Protocols, Second Edition by Paul Birch, John Jones, Jorunn Bos (Editors) expands upon the first edition with current, detailed protocols for the study of plant pathogen genome sequences. It contains new chapters on techniques to help identify and characterize effectors and to study their impacts on host immunity and their roles in pathogen biology. Additional chapters focus on protocols to identify avirulence and resistance genes, investigate the roles of effector targets and other defence-associated proteins in plant immunity. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols and tips on troubleshooting and avoiding known pitfalls.


Via Kamoun Lab @ TSL
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Rescooped by Gigy Varghese from Plants and Microbes
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PNAS: Host plant peptides elicit a transcriptional response to control the Sinorhizobium meliloti cell cycle during symbiosis (2014)

PNAS: Host plant peptides elicit a transcriptional response to control the Sinorhizobium meliloti cell cycle during symbiosis (2014) | plant microbial interaction | Scoop.it

The α-proteobacterium Sinorhizobium meliloti establishes a chronic intracellular infection during the symbiosis with its legume hosts. Within specialized host cells, S. meliloti differentiates into highly polyploid, enlarged nitrogen-fixing bacteroids. This differentiation is driven by host cells through the production of defensin-like peptides called “nodule-specific cysteine-rich” (NCR) peptides. Recent research has shown that synthesized NCR peptides exhibit antimicrobial activity at high concentrations but cause bacterial endoreduplication at sublethal concentrations. We leveraged synchronized S. meliloti populations to determine how treatment with a sublethal NCR peptide affects the cell cycle and physiology of bacteria at the molecular level. We found that at sublethal levels a representative NCR peptide specifically blocks cell division and antagonizes Z-ring function. Gene-expression profiling revealed that the cell division block was produced, in part, through the substantial transcriptional response elicited by sublethal NCR treatment that affected ∼15% of the genome. Expression of critical cell-cycle regulators, including ctrA, and cell division genes, including genes required for Z-ring function, were greatly attenuated in NCR-treated cells. In addition, our experiments identified important symbiosis functions and stress responses that are induced by sublethal levels of NCR peptides and other antimicrobial peptides. Several of these stress-response pathways also are found in related α-proteobacterial pathogens and might be used by S. meliloti to sense host cues during infection. Our data suggest a model in which, in addition to provoking stress responses, NCR peptides target intracellular regulatory pathways to drive S. meliloti endoreduplication and differentiation during symbiosis.


Via Kamoun Lab @ TSL
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Rescooped by Gigy Varghese from Rhizobium Research
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Genetic basis of cytokinin and auxin functions during root nodule development.

Genetic basis of cytokinin and auxin functions during root nodule development. | plant microbial interaction | Scoop.it

\The phytohormones cytokinin and auxin are essential for the control of diverse aspects of cell proliferation and differentiation processes in plants. Although both phytohormones have been suggested to play key roles in the regulation of root nodule development, only recently, significant progress has been made in the elucidation of the molecular genetic basis of cytokinin action in the model leguminous species, and . Identification and functional analyses of the putative cytokinin receptors LOTUS HISTIDINE KINASE 1 and CYTOKININ RESPONSE 1 have brought a greater understanding of how activation of cytokinin signaling is crucial to the initiation of nodule primordia. Recent studies have also started to shed light on the roles of auxin in the regulation of nodule development. Here, we review the history and recent progress of research into the roles of cytokinin and auxin, and their possible interactions, in nodule development.

 

Suzaki T, Ito M, Kawaguchi M. (2013).  Front Plant Sci. 4:42. . Epub Mar 11.


Via IvanOresnik
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Edel Perez Lopez's curator insight, August 23, 2013 2:10 AM

Great, I need read this...

Rescooped by Gigy Varghese from Plants and Microbes
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PLOS Genetics: Arabidopsis thaliana RESISTANCE TO FUSARIUM OXYSPORUM 2 Implicates Tyrosine-Sulfated Peptide Signaling in Susceptibility and Resistance to Root Infection (2013)

PLOS Genetics: Arabidopsis thaliana RESISTANCE TO FUSARIUM OXYSPORUM 2 Implicates Tyrosine-Sulfated Peptide Signaling in Susceptibility and Resistance to Root Infection (2013) | plant microbial interaction | Scoop.it

In the plant Arabidopsis thaliana, multiple quantitative trait loci (QTLs), including RFO2, account for the strong resistance of accession Columbia-0 (Col-0) and relative susceptibility of Taynuilt-0 (Ty-0) to the vascular wilt fungus Fusarium oxysporum forma specialis matthioli. We find that RFO2 corresponds to diversity in receptor-like protein (RLP) genes. In Col-0, there is a tandem pair of RLP genes: RFO2/At1g17250 confers resistance while RLP2 does not. In Ty-0, the highly diverged RFO2 locus has one RLP gene conferring weaker resistance. While the endogenous RFO2 makes a modest contribution to resistance, transgenic RFO2 provides strong pathogen-specific resistance. The extracellular leucine-rich repeats (eLRRs) in RFO2 and RLP2 are interchangeable for resistance and remarkably similar to eLRRs in the receptor-like kinase PSY1R, which perceives tyrosine-sulfated peptide PSY1. Reduced infection inpsy1r and mutants of related phytosulfokine (PSK) receptor genes PSKR1 and PSKR2 shows that tyrosine-sulfated peptide signaling promotes susceptibility. The related eLRRs in RFO2 and PSY1R are not interchangeable; and expression of the RLP nPcR, in which eLRRs in RFO2 are replaced with eLRRs in PSY1R, results in constitutive resistance. Counterintuitively, PSY1 signaling suppresses nPcR because psy1r nPcR is lethal. The fact that PSK signaling does not similarly affect nPcR argues that PSY1 signaling directly downregulates the expression of nPcR. Our results support a speculative but intriguing model to explain RFO2's role in resistance. We propose that F. oxysporum produces an effector that inhibits the normal negative feedback regulation of PSY1R, which stabilizes PSY1 signaling and induces susceptibility. However, RFO2, acting as a decoy receptor for PSY1R, is also stabilized by the effector and instead induces host immunity. Overall, the quantitative resistance of RFO2 is reminiscent of the better-studied monogenic resistance traits.


Via Kamoun Lab @ TSL
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Rescooped by Gigy Varghese from Plants and Microbes
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Plant Physiology: The leucine-rich repeat receptor-like kinase BAK1 and the cytochrome P450 PAD3 contribute to innate immunity to aphids in Arabidopsis (2014)

Plant Physiology: The leucine-rich repeat receptor-like kinase BAK1 and the cytochrome P450 PAD3 contribute to innate immunity to aphids in Arabidopsis (2014) | plant microbial interaction | Scoop.it

The importance of pathogen-associated molecular patterns (PAMPs)-triggered immunity (PTI) against microbial pathogens has been recently demonstrated. However, it is currently unclear if this layer of immunity mediated by surface-localized pattern recognition receptors (PRRs) also plays a role in basal resistance to insects, such as aphids. Here we show that PTI is an important component of plant innate immunity to insects. Extract of the green peach aphid (GPA) Myzus persicae triggers responses characteristic of PTI in Arabidopsis. Two separate eliciting GPA-derived fractions trigger induced-resistance to GPA that is dependent on the leucine-rich repeat receptor like kinase (LRR-RLK) BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1/ SOMATIC-EMBRYOGENESIS RECEPTOR-LIKE KINASE3 (BAK1/AtSERK3), which is a key regulator of several LRR-containing PRRs. BAK1 is required for GPA elicitor-mediated induction of reactive oxygen species (ROS) and callose deposition. Arabidopsis bak1 mutant plants are also compromised in immunity to Acyrthosiphon pisum (pea aphid) for which Arabidopsis is normally a non-host. Aphid-derived elicitors induce expression of PHYTOALEXIN DEFICIENT 3 (PAD3), a key cytochrome P450 involved in the biosynthesis of camalexin, which is a major Arabidopsis phytoalexin that is toxic to GPA. PAD3 is also required for induced-resistance to GPA, independently of BAK1 and ROS production. Our results reveal that plant innate immunity to insects may involve early perception of elicitors by cell surface-localized PRRs leading to subsequent downstream immune signaling.


Via Kamoun Lab @ TSL
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Rescooped by Gigy Varghese from Effectors and Plant Immunity
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Nat. Rev. Microbiol.: Focus on Plant Microbe Interactions (2013)

Microbial ecology: A bacterial decoy skews plant defences

Christina Tobin Kåhrström

 

Symbiosis: Non-legumes answer the rhizobial call

Rachel David

 

RNA silencing suppression by plant pathogens: defence, counter-defence and counter-counter-defence

Nathan Pumplin & Olivier Voinnet

 

On the front line: structural insights into plant–pathogen interactions

Lennart Wirthmueller, Abbas Maqbool & Mark J. Banfield

 

Geminiviruses: masters at redirecting and reprogramming plant processes

Linda Hanley-Bowdoin, Eduardo R. Bejarano, Dominique Robertson & Shahid Mansoor

 

Going back to the roots: the microbial ecology of the rhizosphere

Laurent Philippot, Jos M. Raaijmakers, Philippe Lemanceau & Wim H. van der Putten

 

Filamentous plant pathogen effectors in action

Martha C. Giraldo & Barbara Valent


Via Nicolas Denancé
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Steve Marek's curator insight, October 17, 2013 12:49 PM

Great Review Issue!

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Nature Reviews Microbiology: Going back to the roots: the microbial ecology of the rhizosphere (2013)

Nature Reviews Microbiology: Going back to the roots: the microbial ecology of the rhizosphere (2013) | plant microbial interaction | Scoop.it

The rhizosphere is the interface between plant roots and soil where interactions among a myriad of microorganisms and invertebrates affect biogeochemical cycling, plant growth and tolerance to biotic and abiotic stress. The rhizosphere is intriguingly complex and dynamic, and understanding its ecology and evolution is key to enhancing plant productivity and ecosystem functioning. Novel insights into key factors and evolutionary processes shaping the rhizosphere microbiome will greatly benefit from integrating reductionist and systems-based approaches in both agricultural and natural ecosystems. Here, we discuss recent developments in rhizosphere research in relation to assessing the contribution of the micro- and macroflora to sustainable agriculture, nature conservation, the development of bio-energy crops and the mitigation of climate change.


Via Francis Martin, Kamoun Lab @ TSL
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