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Rescooped by Tien Tran from Plantparasitic nematode
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Effector assays: Green islands following agroinfiltration of tobacco (2012)

Effector assays: Green islands following agroinfiltration of tobacco (2012) | Plantparasitic nematode | Scoop.it

A warning about inadvertent effects of agroinfiltration in tobacco to add to the discussion "Some effector assays are prone to artefacts" (link below). Thanks to Jeff Ellis for contributing the image and the interpretation.

 

Figure shows a tobacco leaf infiltrated with Agrobacterium tumefaciens GV3101 pMP90 resuspended at OD600=1 in 10 mM MgCl and containing various binary constructs. The plants were left in the glasshouse a long time after the experiment and had clearly run out of nutrients.The green island effect could be due to cytokinin made by A. tumefaciens. Nopaline strains do it in 2 ways, the tzs gene, which is acetosyringone inducible, and in the vir region of the Ti plasmid, and breakdown of tRNA.

 

Transient assays of genes that are influenced by cytokinin would probably be affected and results could be confusing.

 

More at http://storify.com/KamounLab/some-effector-assays-are-prone-to-artefacts


Via Kamoun Lab @ TSL, The aphid team@INRA Rennes, Tien Tran
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How to get thoughtful responses to exam questions?

How to get thoughtful responses to exam questions? | Plantparasitic nematode | Scoop.it

Someone asked for advice about how to get more thoughtful answers to exam questions, and in the ensuing discussion one person suggested "Ask thoughtful questions". This is great advice, but it's harder than it sounds. I'll be collecting and sharing some examples to inspire you to ask thoughtful questions of your students.

 

A key to success in asking such a question is to prepare the students in advance - you have to show them other, similar questions, hypothesis and experiments that they can use as models in their responses to a different but similar question.

 

To help them develop the ability to ponder this question, I prepared students  by discussing three classic experimentsover several different class periods.  The first was Darwin's study of light perception in coleoptiles to elicit their bending response to unidirectional light. Darwin asked where the light was perceived by masking different parts of the plant. (So that's one question a student could ask about resveratrol - which part of the plant perceives the light).

Another experiment we studied was the induction of flowering by daylength. Here I introduced not only the question of where light was perceived, but also the wavelength of light that elicits the response, the duration of the light signal needed, and the time required between message elicitation and its reception in the shoot meristem (all reasonable questions to ask about resveratrol production).

Finally, we looked at systemic acquired resistance to pathogens and pests, again examining experiments to investigate where the stimulus is perceived, the nature of the signal, how it travels to distal tissues etc.

 

Ideally, before an exam you'll work through a similar problem with students, by asking them to propose hypotheses and experiments and giving feedback on their responses. This can be done as homework assignments or during class time, which works particularly well because students can hear what other students propose andso learn from their peers' ideas and thoughts.


Via Mary Williams
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Mary Williams's curator insight, July 19, 2015 1:23 PM

Do you have a thoughtful  plant biology question you've used for assessment that you're willing to share? Drop me a line if you do!

Rescooped by Tien Tran from Plant, Insect and Microbe Interactions
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Effector assays: Green islands following agroinfiltration of tobacco (2012)

Effector assays: Green islands following agroinfiltration of tobacco (2012) | Plantparasitic nematode | Scoop.it

A warning about inadvertent effects of agroinfiltration in tobacco to add to the discussion "Some effector assays are prone to artefacts" (link below). Thanks to Jeff Ellis for contributing the image and the interpretation.

 

Figure shows a tobacco leaf infiltrated with Agrobacterium tumefaciens GV3101 pMP90 resuspended at OD600=1 in 10 mM MgCl and containing various binary constructs. The plants were left in the glasshouse a long time after the experiment and had clearly run out of nutrients.The green island effect could be due to cytokinin made by A. tumefaciens. Nopaline strains do it in 2 ways, the tzs gene, which is acetosyringone inducible, and in the vir region of the Ti plasmid, and breakdown of tRNA.

 

Transient assays of genes that are influenced by cytokinin would probably be affected and results could be confusing.

 

More at http://storify.com/KamounLab/some-effector-assays-are-prone-to-artefacts


Via Kamoun Lab @ TSL, The aphid team@INRA Rennes
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Plant Phys: The effector SPRYSEC-19 of Globodera rostochiensis suppresses CC-NB-LRR-mediated disease resistance in plants (2012)

Plant Phys: The effector SPRYSEC-19 of Globodera rostochiensis suppresses CC-NB-LRR-mediated disease resistance in plants (2012) | Plantparasitic nematode | Scoop.it

The potato cyst nematode Globodera rostochiensis invades roots of host plants where it transforms cells near the vascular cylinder into a permanent feeding site. The host cell modifications are most likely induced by a complex mixture of proteins in the stylet secretions of the nematodes. Resistance to nematodes conferred by NB-LRR proteins usually results in a programmed cell death in and around the feeding site, and is most likely triggered by the recognition of effectors in stylet secretions. However, the actual role of these secretions in the activation and suppression of effector-triggered immunity is largely unknown. Here we demonstrate that the effector SPRYSEC-19 of Globodera rostochiensis physically associates in planta with the leucine-rich repeat (LRR) domain of a member of the SW5 resistance gene cluster in tomato (Solanum lycopersicum). Unexpectedly, this interaction did not trigger defense-related programmed cell death and resistance to G. rostochiensis. By contrast, agroinfiltration assays showed that the co-expression of SPRYSEC-19 in leaves of Nicotiana benthamiana suppresses programmed cell death mediated by several CC-NB-LRR immune receptors. Furthermore, SPRYSEC-19 abrogated resistance to Potato Virus X mediated by the CC-NB-LRR resistance protein Rx1, and resistance to Verticillium dahliae mediated by an unidentified resistance in potato. The suppression of cell death and disease resistance did not require a physical association of SPRYSEC-19 and the LRR domains of the CC-NB-LRR resistance proteins. Altogether, our data demonstrated that potato cyst nematodes secrete effectors that enable the suppression of programmed cell death and disease resistance mediated by several CC-NB-LRR proteins in plants.


Via Kamoun Lab @ TSL
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RESEARCH AND MARKETS: Active Projects in Research and Development of ... - 4-traders (press release)

RESEARCH AND MARKETS: Active Projects in Research and Development of ... - 4-traders (press release) | Plantparasitic nematode | Scoop.it
RESEARCH AND MARKETS: Active Projects in Research and Development of ...
4-traders (press release)
Pim kinases are critical downstream effectors of the ABL, JAK2, and Flt-3 oncogenes and are required by them to drive tumorigenesis.
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Book: Effectors in Plant-Microbe Interactions

Book: Effectors in Plant-Microbe Interactions | Plantparasitic nematode | Scoop.it

Plants and microbes interact in a complex relationship that can have both harmful and beneficial impacts on both plant and microbial communities. Effectors, secreted microbial molecules that alter plant processes and facilitate colonization, are central to understanding the complicated interplay between plants and microbes. Effectors in Plant-Microbe Interactions unlocks the molecular basis of this important class of microbial molecules and describes their diverse and complex interactions with host plants.


Effectors in Plant Microbe Interactions is divided into five sections that take stock of the current knowledge on effectors of plant-associated organisms. Coverage ranges from the impact of bacterial, fungal and oomycete effectors on plant immunity and high-throughput genomic analysis of effectors to the function and trafficking of these microbial molecules. The final section looks at effectors secreted by other eukaryotic microbes that are the focus of current and future research efforts.

 

Written by leading international experts in plant-microbe interactions, Effectors in Plant Microbe Interactions, will be an essential volume for plant biologists, microbiologists, pathologists, and geneticists.


Via Kamoun Lab @ TSL, Ithacawang
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Engineering Plant Disease Resistance Based on TAL Effectors - Annual Review of Phytopathology

Engineering Plant Disease Resistance Based on TAL Effectors - Annual Review of Phytopathology | Plantparasitic nematode | Scoop.it

Schornack et al. (2013) [in advance version, changes will occur]

 

Transcription activator-like (TAL) effectors are encoded by plantpathogenic bacteria and induce expression of plant host genes. TAL effectors bind DNA on the basis of a unique code that specifies binding of amino acid residues in repeat units to particular DNA bases in a one-to-one correspondence. This code can be used to predict binding sites of natural TAL effectors and to design novel synthetic DNA-binding domains for targeted genome manipulation. Natural mechanisms of resistance in plants against TAL effector–containing pathogens have given insights into new strategies for disease control.


Via dromius
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Rescooped by Tien Tran from Plant Biology Teaching Resources (Higher Education)
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How to get thoughtful responses to exam questions?

How to get thoughtful responses to exam questions? | Plantparasitic nematode | Scoop.it

Someone asked for advice about how to get more thoughtful answers to exam questions, and in the ensuing discussion one person suggested "Ask thoughtful questions". This is great advice, but it's harder than it sounds. I'll be collecting and sharing some examples to inspire you to ask thoughtful questions of your students.

 

A key to success in asking such a question is to prepare the students in advance - you have to show them other, similar questions, hypothesis and experiments that they can use as models in their responses to a different but similar question.

 

To help them develop the ability to ponder this question, I prepared students  by discussing three classic experimentsover several different class periods.  The first was Darwin's study of light perception in coleoptiles to elicit their bending response to unidirectional light. Darwin asked where the light was perceived by masking different parts of the plant. (So that's one question a student could ask about resveratrol - which part of the plant perceives the light).

Another experiment we studied was the induction of flowering by daylength. Here I introduced not only the question of where light was perceived, but also the wavelength of light that elicits the response, the duration of the light signal needed, and the time required between message elicitation and its reception in the shoot meristem (all reasonable questions to ask about resveratrol production).

Finally, we looked at systemic acquired resistance to pathogens and pests, again examining experiments to investigate where the stimulus is perceived, the nature of the signal, how it travels to distal tissues etc.

 

Ideally, before an exam you'll work through a similar problem with students, by asking them to propose hypotheses and experiments and giving feedback on their responses. This can be done as homework assignments or during class time, which works particularly well because students can hear what other students propose andso learn from their peers' ideas and thoughts.


Via Mary Williams
more...
Mary Williams's curator insight, July 19, 2015 1:23 PM

Do you have a thoughtful  plant biology question you've used for assessment that you're willing to share? Drop me a line if you do!

Rescooped by Tien Tran from Plants and Microbes
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Classic paper: Plant Science: An Agrobacterium-mediated transient gene expression system for intact leaves (1997)

Classic paper: Plant Science: An Agrobacterium-mediated transient gene expression system for intact leaves (1997) | Plantparasitic nematode | Scoop.it

An efficient and reproducible Agrobacterium-mediated transient gene expression system for intact leaf tissue was developed. A high level of transient expression was observed when bacteria, which were pretreated in vir gene-inducing conditions, were infiltrated into complete leaf tissue. Histochemical β-glucuronidase assays showed large transgene-expressing sectors comprising of up to 90% of the leaf area. As a consequence of infiltration, the induced bacteria entered into the intercellular spaces, thus cnabling T-DNA transfer in all cell layers of the leaf. The protocol was optimized for Phascolus vulgaris leaves, but similar results were obtained with other plant species, such as Phaseolus acutifolius, poplar, and tobacco. A β-glucuronidase chimeric gene interrupted by an intron was used as a marker for histological detection of the sectors.


Via Kamoun Lab @ TSL
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Molecular Plant-Microbe Interactions (2013): Optimized Agroinfiltration and Virus-Induced Gene Silencing to Study Ve1-Mediated Verticillium Resistance in Tobacco

Molecular Plant-Microbe Interactions (2013): Optimized Agroinfiltration and Virus-Induced Gene Silencing to Study Ve1-Mediated Verticillium Resistance in Tobacco | Plantparasitic nematode | Scoop.it

Recognition of pathogen effectors by plant immune receptors often leads to the activation of a hypersensitive response (HR), which is a rapid and localized cell death of plant tissue surrounding the site at which recognition occurs. Due to its particular amenability to transient assays for functional genetics, tobacco is a model for immune signaling in the Solanaceae plant family. Here, we show that coexpression of the tomato (Solanum lycopersicum) immune receptor Ve1 and the corresponding Verticillium effector protein Ave1 leads to HR only in particular tobacco species. Whereas HR is obtained in Nicotiana tabacum, no such response is obtained in N. benthamiana. Furthermore, our analysis revealed an endogenous Ve1 ortholog in Nicotiana glutinosa, as expression of Ave1 in absence of Ve1 induced a HR, and N. glutinosa was found to be resistant against race 1 Verticillium dahliae. We furthermore report the establishment of virus-induced gene silencing in N. tabacum for functional analysis of Ve1 signaling. Collectively, our data show that N. tabacum can be used as a model plant to study Ve1-mediated immune signaling.

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Molecular Plant Pathology: Top 10 plant-parasitic nematodes in molecular plant pathology (2013)

Molecular Plant Pathology: Top 10 plant-parasitic nematodes in molecular plant pathology (2013) | Plantparasitic nematode | Scoop.it

The aim of this review was to undertake a survey of researchers working with plant-parasitic nematodes in order to determine a ‘top 10’ list of these pathogens based on scientific and economic importance. Any such list will not be definitive as economic importance will vary depending on the region of the world in which a researcher is based. However, care was taken to include researchers from as many parts of the world as possible when carrying out the survey. The top 10 list emerging from the survey is composed of: (1) root-knot nematodes (Meloidogyne spp.); (2) cyst nematodes (Heterodera and Globodera spp.); (3) root lesion nematodes (Pratylenchus spp.); (4) the burrowing nematode Radopholus similis; (5) Ditylenchus dipsaci; (6) the pine wilt nematode Bursaphelenchus xylophilus; (7) the reniform nematodeRotylenchulus reniformis; (8) Xiphinema index (the only virus vector nematode to make the list); (9) Nacobbus aberrans; and (10)Aphelenchoides besseyi. The biology of each nematode (or nematode group) is reviewed briefly.


Via Kamoun Lab @ TSL, Food Security
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Petter Françoise's curator insight, October 10, 2013 2:48 AM

many are recommended for regulation by EPPO

Rescooped by Tien Tran from Plant Immunity And Microbial Effectors
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PLOS ONE: Phytophthora Have Distinct Endogenous Small RNA Populations That Include Short Interfering and microRNAs

PLOS ONE: Phytophthora Have Distinct Endogenous Small RNA Populations That Include Short Interfering and microRNAs | Plantparasitic nematode | Scoop.it

In eukaryotes, RNA silencing pathways utilize 20-30-nucleotide small RNAs to regulate gene expression, specify and maintain chromatin structure, and repress viruses and mobile genetic elements. RNA silencing was likely present in the common ancestor of modern eukaryotes, but most research has focused on plant and animal RNA silencing systems. Phytophthora species belong to a phylogenetically distinct group of economically important plant pathogens that cause billions of dollars in yield losses annually as well as ecologically devastating outbreaks. We analyzed the small RNA-generating components of the genomes of P. infestans, P. sojae and P. ramorum using bioinformatics, genetic, phylogenetic and high-throughput sequencing-based methods. 


Via IPM Lab
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A Simple and Efficient Method for Assembling TALE Protein Based on Plasmid Library

A Simple and Efficient Method for Assembling TALE Protein Based on Plasmid Library | Plantparasitic nematode | Scoop.it

DNA binding domain of the transcription activator-like effectors (TALEs) from Xanthomonas sp. consists of tandem repeats that can be rearranged according to a simple cipher to target new DNA sequences with high DNA-binding specificity. This technology has been successfully applied in varieties of species for genome engineering. However, assembling long TALE tandem repeats remains a big challenge precluding wide use of this technology. Although several new methodologies for efficiently assembling TALE repeats have been recently reported, all of them require either sophisticated facilities or skilled technicians to carry them out. In a recent paper, researchers described a simple and efficient method for generating customized TALE nucleases (TALENs) and TALE transcription factors (TALE-TFs) based on TALE repeat tetramer library. A tetramer library consisting of 256 tetramers covers all possible combinations of 4 base pairs. A set of unique primers was designed for amplification of these tetramers. PCR products were assembled by one step of digestion/ligation reaction. 12 TALE constructs including 4 TALEN pairs targeted to mouse Gt(ROSA)26Sor gene and mouse Mstn gene sequences as well as 4 TALE-TF constructs targeted to mouse Oct4, c-Myc, Klf4 and Sox2 gene promoter sequences were generated by using our method. The construction routines took 3 days and parallel constructions were available. The rate of positive clones during colony PCR verification was 64% on average. Sequencing results suggested that all TALE constructs were performed with high successful rate. This is a rapid and cost-efficient method using the most common enzymes and facilities with a high success rate.


Via dromius, Dr. Stefan Gruenwald
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TAL effectors: highly adaptable phytobacterial virulence factors and readily engineered DNA-targeting proteins - Trends Cell Biol

TAL effectors: highly adaptable phytobacterial virulence factors and readily engineered DNA-targeting proteins - Trends Cell Biol | Plantparasitic nematode | Scoop.it

 

(via Tom Schreiber, thx)

Doyle et al, 2013

Transcription activator-like (TAL) effectors are transcription factors injected into plant cells by pathogenic bacteria of the genus Xanthomonas. They function as virulence factors by activating host genes important for disease, or as avirulence factors by turning on genes that provide resistance. DNA-binding specificity is encoded by polymorphic repeats in each protein that correspond one-to-one with different nucleotides. This code has facilitated target identification and opened new avenues for engineering disease resistance. It has also enabled TAL effector customization for targeted gene control, genome editing, and other applications. This article reviews the structural basis for TAL effector-DNA specificity, the impact of the TAL effector-DNA code on plant pathology and engineered resistance, and recent accomplishments and future challenges in TAL effector-based DNA targeting.


Via dromius
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