Plants and Microbes
307.6K views | +34 today
Follow
 
Scooped by Kamoun Lab @ TSL
onto Plants and Microbes
Scoop.it!

Nature Communications: An insect-induced novel plant phenotype for sustaining social life in a closed system (2012)

Nature Communications: An insect-induced novel plant phenotype for sustaining social life in a closed system (2012) | Plants and Microbes | Scoop.it

Foraging, defense and waste disposal are essential for sustaining social insect colonies. Hence, their nest generally has an open structure, wherein specialized castes called workers and soldiers perform these tasks. However, some social aphids form completely closed galls, wherein hundreds to thousands of insects grow and reproduce for several months in isolation. Why these social aphids are not drowned by accumulated honeydew has been an enigma. Here we report a sophisticated biological solution to the waste problem in the closed system: the gall inner surface is specialized for absorbing water, whereby honeydew is promptly removed via the plant vascular system. The water-absorbing closed galls have evolved at least twice independently among social aphids. The plant-mediated waste removal, which entails insect’s manipulation of plant morphogenesis and physiology, comprises a previously unknown mechanism of nest cleaning, which can be regarded as ‘extended phenotype’ and ‘indirect social behavior’ of the social aphids.

more...
No comment yet.
Plants and Microbes
Everything related to the science of plant-microbe interactions
Your new post is loading...
Your new post is loading...
Scooped by Kamoun Lab @ TSL
Scoop.it!

YouTube: Engineering resistance in banana against Fusarium Wilt disease (2017)

Bananas are more than delicious fruits, bananas are the fourth most important food crop in the world. Currently, the biggest threat to worldwide banana production is Fusarium Wilt. I am a scientist working to engineer resistance in banana against this devastating disease. If you want to know more about bananas, check out my blog, write me a mail, follow me on Twitter or stay tuned to this channel.

more...
No comment yet.
Rescooped by Kamoun Lab @ TSL from Plant Pathogenomics
Scoop.it!

bioRxiv: Gene flow between divergent cereal- and grass-specific lineages of the rice blast fungus Magnaporthe oryzae (2017)

bioRxiv: Gene flow between divergent cereal- and grass-specific lineages of the rice blast fungus Magnaporthe oryzae (2017) | Plants and Microbes | Scoop.it

Delineating species and epidemic lineages in fungal plant pathogens is critical to our understanding of disease emergence and the structure of fungal biodiversity, and also informs international regulatory decisions. Pyricularia oryzae (syn. Magnaporthe oryzae) is a multi-host pathogen that infects multiple grasses and cereals, is responsible for the most damaging rice disease (rice blast), and of growing concern due to the recent introduction of wheat blast to Bangladesh from South America. However, the genetic structure and evolutionary history of M. oryzae, including the possible existence of cryptic phylogenetic species, remain poorly defined. Here, we use whole-genome sequence information for 76 M. oryzae isolates sampled from 12 grass and cereal genera to infer the population structure of M. oryzae, and to reassess the species status of wheat-infecting populations of the fungus. Species recognition based on genealogical concordance, using published data or extracting previously-used loci from genome assemblies, failed to confirm a prior assignment of wheat blast isolates to a new species (Pyricularia graminis tritici). Inference of population subdivisions revealed multiple divergent lineages within M. oryzae, each preferentially associated with one host genus, suggesting incipient speciation following host shift or host range expansion. Analyses of gene flow, taking into account the possibility of incomplete lineage sorting, revealed that genetic exchanges have contributed to the makeup of multiple lineages within M. oryzae. These findings provide greater understanding of the eco-evolutionary factors that underlie the diversification of M. oryzae and highlight the practicality of genomic data for epidemiological surveillance in this important multi-host pathogen.

more...
No comment yet.
Rescooped by Kamoun Lab @ TSL from Plant pathogenic fungi
Scoop.it!

Scientific Reports: Fungal infestation boosts fruit aroma and fruit removal by mammals and birds (2017)

Scientific Reports: Fungal infestation boosts fruit aroma and fruit removal by mammals and birds (2017) | Plants and Microbes | Scoop.it

For four decades, an influential hypothesis has posited that competition for food resources between microbes and vertebrates selects for microbes to alter these resources in ways that make them unpalatable to vertebrates. We chose an understudied cross kingdom interaction to experimentally evaluate the effect of fruit infection by fungi on both vertebrate (mammals and birds) fruit preferences and on ecologically relevant fruit traits (volatile compounds, toughness, etc). Our well-replicated field experiments revealed that, in contrast to previous studies, frugivorous mammals and birds consistently preferred infested over intact fruits. This was concordant with the higher level of attractive volatiles (esters, ethanol) in infested fruits. This investigation suggests that vertebrate frugivores, fleshy-fruited plants, and microbes form a tripartite interaction in which each part could interact positively with the other two (e.g. both orange seeds and fungal spores are likely dispersed by mammals). Such a mutualistic view of these complex interactions is opposed to the generalized idea of competition between frugivorous vertebrates and microorganisms. Thus, this research provides a new perspective on the widely accepted plant evolutionary dilemma to make fruits attractive to mutualistic frugivores while unattractive to presumed antagonistic microbes that constrain seed dispersal.


Via Steve Marek
more...
No comment yet.
Rescooped by Kamoun Lab @ TSL from Publications
Scoop.it!

PNAS: NLR network mediates immunity to diverse plant pathogens (2017)

PNAS: NLR network mediates immunity to diverse plant pathogens (2017) | Plants and Microbes | Scoop.it

Both plants and animals rely on nucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins to respond to invading pathogens and activate immune responses. An emerging concept of NLR function is that “sensor” NLR proteins are paired with “helper” NLRs to mediate immune signaling. However, our fundamental knowledge of sensor/helper NLRs in plants remains limited. In this study, we discovered a complex NLR immune network in which helper NLRs in the NRC (NLR required for cell death) family are functionally redundant but display distinct specificities toward different sensor NLRs that confer immunity to oomycetes, bacteria, viruses, nematodes, and insects. The helper NLR NRC4 is required for the function of several sensor NLRs, including Rpi-blb2, Mi-1.2, and R1, whereas NRC2 and NRC3 are required for the function of the sensor NLR Prf. Interestingly, NRC2, NRC3, and NRC4 redundantly contribute to the immunity mediated by other sensor NLRs, including Rx, Bs2, R8, and Sw5. NRC family and NRC-dependent NLRs are phylogenetically related and cluster into a well-supported superclade. Using extensive phylogenetic analysis, we discovered that the NRC superclade probably emerged over 100 Mya from an NLR pair that diversified to constitute up to one-half of the NLRs of asterids. These findings reveal a complex genetic network of NLRs and point to a link between evolutionary history and the mechanism of immune signaling. We propose that this NLR network increases the robustness of immune signaling to counteract rapidly evolving plant pathogens.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Nature Microbiology: Fungal pathogenesis: Combatting the oxidative burst (2017)

Nature Microbiology: Fungal pathogenesis: Combatting the oxidative burst (2017) | Plants and Microbes | Scoop.it

See also Marroquin-Guzman et al. The Magnaporthe oryzae nitrooxidative stress response suppresses rice innate immunity during blast disease https://www.nature.com/articles/nmicrobiol201754

 

Plants respond to microbial attack with a lethal burst of reactive oxygen species. How then, do pathogens successfully invade plants? Unexpectedly, a link between primary metabolism and suppression of plant immunity allows the rice blast fungus Magnaporthe oryzae to grow in such a hostile environment.

 

Plant-infecting fungi and oomycetes are an ever present threat to global food security — each year they destroy sufficient food to feed half a billion people1. Understanding how these pathogens infect and colonize host plants is therefore crucial if we are to develop new strategies to fight fungal diseases and improve plant health. The rice blast fungus Magnaporthe oryzae is responsible for the most devastating disease of cultivated rice, the primary staple for more than half of the world's population2. Strains of the same fungus also cause blast disease of wheat, a new disease that is currently causing a severe outbreak in Bangladesh and India3. Because of its economic significance and genetic tractability, rice blast disease has also emerged as a major model for studying the molecular and cellular basis of fungal infection2,4. Similar to many pathogenic fungi, M. oryzae has evolved highly sophisticated ways to invade plant cells and disable their defence systems.

 

One of the earliest responses of plants to microbial attack is the induction of a rapid, transient burst of reactive oxygen species5 (ROS). This oxidative burst is a potent defence reaction that will kill any unsuspecting microorganism. How can pathogens still successfully invade plant cells and contend with such high concentrations of ROS? In this issue of Nature Microbiology, Marroquin-Guzman and colleagues report that a link between primary fungal metabolism and the suppression of plant immunity enables M. oryzae to protect itself from nitrooxidative stress and maintain redox balance within living rice cells6, thereby facilitating its growth within such a hostile environment.

 

To initiate rice infection, a fungal spore adheres tightly to the rice leaf surface, germinates, and rapidly elaborates a specialized infection structure called an appressorium that is used to breach the tough outer leaf cuticle4. Once inside a host cell, the fungus develops bulbous, branched hyphae that maintain intimate contact with the plasma membrane of the living plant cell, forming a specialized biotrophic interfacial complex7. The pathogen and host then engage in an intense molecular dialogue; plant metabolism is reprogrammed to the pathogen's benefit and the host immune response is suppressed4,7. Much recent research has focused on fungal effector proteins, a highly diverse group of secreted molecules that target immune responses in the host to facilitate pathogen infection and spread8. However, fungi have clearly evolved additional ways to keep plant defences at bay. Marroquin-Guzman and colleagues identified and characterized nitronate monooxygenase (NMO) from M. oryzae, an enzyme normally used by fungal cells to protect themselves from nitrooxidative stress6. They show, however, that NMO is also required for utilization of nitrate and nitrite as nitrogen sources and for maintaining redox balance within living rice cells during pathogen colonization. The latter role of NMO is essential for pathogenicity, because it provides a novel mechanism by which the fungus can prevent elicitation of the plant oxidative burst (Fig. 1).

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Vimeo: Soil Life in Action: Tomato Plants with fungal infection (2017)

Time-lapse of a healthy tomato plant (left) and a tomato plant that was inoculated with the fungus Verticillium dahliae (right).The effect on the root and stem development is visible.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Plantae: In Brief: An Emerging Paradigm? RxLR Cleavage Before Effector Secretion (2017)

Plantae: In Brief: An Emerging Paradigm? RxLR Cleavage Before Effector Secretion (2017) | Plants and Microbes | Scoop.it

Eukaryotic pathogens are responsible for devastating plant diseases that threaten food supplies globally – think potato blight caused by the oomycete Phytophora infestans, rice blast caused by the fungus Magnaporthe oryzae, and wheat stem rust caused by the fungus Puccinia graminis f. sp. tritici. These pathogens secrete effector proteins that condition the host cells for successful infection, some by acting in the apoplast and others after entering into the host cells. Many oomycete effectors have an RxLR sequence motif in their N-terminal region that seems to function in host cell targeting, although the mechanisms are a matter of debate (reviewed in Wawra et al., 2012 and Petre and Kamoun, 2014). It is notoriously difficult to study the secretion and targeting of effectors, as these processes occur only at the interface of the pathogen with the host and only during infection. In fact, there are mounting indications that some alternative approaches often used to assess pathogen effector secretion and entry in the host plant could be flawed (see, for example, Petre et al., http://dx.doi.org/10.1101/038232). In a new Breakthrough Report, Wawra & Trusch et al. (2017) provide evidence that the RxLR motif is important for effector secretion from the pathogen, rather than for direct interaction with the host cells.

 

Plasmodium parasites, which cause malaria, are distantly related to oomycete plant pathogens and similarly have RxLR-like N-terminal sequences that are responsible for targeting to host cells. For many Plasmodium effectors, this so-called PEXEL motif is cleaved in the ER, after which the newly exposed N-terminus is acetylated and the effector is secreted. Another motif, called the TEXEL motif, is important for effector processing in Toxoplasma gondii. The similarity of the RxLR motif to the PEXEL and TEXEL motifs prompted Wawra and coworkers to explore whether RxLR cleavage is involved in effector secretion from P. infestans.

 

Wawra & Trusch et al. isolated the native (untagged) form of the AVR3a effector secreted into the culture medium by P. infestans. LC-MS/MS analysis did not reveal a peptide representing any sequence more N-terminal than the RxLR motif, but did find a peptide that started immediately downstream of the motif. In addition, the MS data showed likely acetylation. To further characterize the secreted form of the effector, the authors performed reverse-phase chromatography followed by MALDI-TOF analysis. After deglycosylation, the mass of the main product indicated that the AVR3a protein from the medium lacked the first 47 amino acids (i.e., the region up to and including the RxLR motif) with an additional mass for a possible acetylation.

 

Wawra and coworkers followed up on the possibility of N-terminal acetylation using Edman degradation, which can cleave an N-terminal peptide bond when it is accessible. They observed no cleavage of the AVR3a peptide from the medium, indicating that the N-terminus was not accessible, consistent with it being acetylated. The likely N-acetylation of AVR3a is particularly intriguing as the acetyltransferases that carry out such N-acetylation are found only inside the cell.

 

Overall, these results are consistent with cleavage of the RxLR motif of AVR3a, followed by acetylation of the new N-terminal amino acid before secretion from P. infestans. It is not clear what protease might be responsible for the cleavage, because none of the 11 P. infestans aspartic proteases homologous to the protease that cleaves the PEXEL motif in Plasmodium could cleave AVR3a in assays using recombinant bacterially expressed proteins. Nevertheless, the potential similarity of this process to the processing and secretion of effectors from other species containing the PEXEL and TEXEL motifs points to its biological relevance and a possible conserved mechanism for effector secretion.

more...
Qiang Zhang's curator insight, June 13, 1:57 AM
Share your insight
Scooped by Kamoun Lab @ TSL
Scoop.it!

bioRxiv: Lipid transfer from plants to arbuscular mycorrhiza fungi (2017)

bioRxiv: Lipid transfer from plants to arbuscular mycorrhiza fungi (2017) | Plants and Microbes | Scoop.it

Arbuscular mycorrhiza (AM) symbioses contribute to global carbon cycles as plant hosts divert up to 20% of photosynthate to the obligate biotrophic fungi. Previous studies suggested carbohydrates as the only form of carbon transferred to the fungi. However, de novo fatty acid (FA) synthesis has not been observed in AM fungi in absence of the plant. In a forward genetic approach, we identified two Lotus japonicus mutants defective in AM-specific paralogs of lipid biosynthesis genes (KASI and GPAT6). These mutants perturb fungal development and accumulation of emblematic fungal 16:1ω5 FAs. Using isotopolog profiling we demonstrate that 13C patterns of fungal FAs recapitulate those of wild-type hosts, indicating cross-kingdom lipid transfer from plants to fungi. This transfer of labelled FAs was not observed for the AM-specific lipid biosynthesis mutants. Thus, growth and development of beneficial AM fungi is not only fueled by sugars but depends on lipid transfer from plant hosts.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Biological Control: Ampelomyces quisqualis—a parasite of powdery mildews

Biological Control: Ampelomyces quisqualis—a parasite of powdery mildews | Plants and Microbes | Scoop.it

The fungus Ampelomyces quisqualis is a naturally occurring hyperparasite of powdery mildews. It infects and forms pycnidia (fruiting bodies) within powdery mildew hyphae, conidiophores (specialized spore-producing hyphae), and cleistothecia (the closed fruiting bodies of powdery mildews). This parasitism reduces growth and may eventually kill the mildew colony. A. quisqualis has been the subject of numerous investigations on biological control of powdery mildews for over 50 years.

more...
No comment yet.
Rescooped by Kamoun Lab @ TSL from Rice Blast
Scoop.it!

New Phytologist: A new proteinaceous pathogen‐associated molecular pattern (PAMP) identified in Ascomycete fungi induces cell death in Solanaceae (2017)

New Phytologist: A new proteinaceous pathogen‐associated molecular pattern (PAMP) identified in Ascomycete fungi induces cell death in Solanaceae (2017) | Plants and Microbes | Scoop.it

Pathogen-associated molecular patterns (PAMPs) are detected by plant pattern recognition receptors (PRRs), which gives rise to PAMP-triggered immunity (PTI). We characterized a novel fungal PAMP, Cell Death Inducing 1 (RcCDI1), identified in the Rhynchosporium commune transcriptome sampled at an early stage of barley (Hordeum vulgare) infection. The ability of RcCDI1 and its homologues from different fungal species to induce cell death in Nicotiana benthamiana was tested following agroinfiltration or infiltration of recombinant proteins produced by Pichia pastoris. Virus-induced gene silencing (VIGS) and transient expression of Phytophthora infestans effectors PiAVR3a and PexRD2 were used to assess the involvement of known components of PTI in N. benthamiana responses to RcCDI1. RcCDI1 was highly upregulated early during barley colonization with R. commune. RcCDI1 and its homologues from different fungal species, including Zymoseptoria tritici, Magnaporthe oryzae and Neurospora crassa, exhibited PAMP activity, inducing cell death in Solanaceae but not in other families of dicots or monocots. RcCDI1-triggered cell death was shown to require N. benthamiana Brassinosteroid insensitive 1-Associated Kinase 1 (NbBAK1), N. benthamiana suppressor of BIR1-1 (NbSOBIR1) and N. benthamiana SGT1 (NbSGT1), but was not suppressed by PiAVR3a or PexRD2. We report the identification of a novel Ascomycete PAMP, RcCDI1, recognized by Solanaceae but not by monocots, which activates cell death through a pathway that is distinct from that triggered by the oomycete PAMP INF1.


Via Elsa Ballini
more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

International Symposium on Potato Late Blight Resistance, Huazhong Agricultural University, 10-14 October 2017

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

bioRxiv: Specific hypersensitive response-associated recognition of new apoplastic effectors from Cladosporium fulvum in wild tomato (2017)

bioRxiv: Specific hypersensitive response-associated recognition of new apoplastic effectors from Cladosporium fulvum in wild tomato (2017) | Plants and Microbes | Scoop.it

Tomato leaf mould disease is caused by the biotrophic fungus Cladosporium fulvum. During infection, C. fulvum produces extracellular small secreted protein (SSP) effectors that function to promote colonization of the leaf apoplast. Resistance to the disease is governed by Cf immune receptor genes that encode receptor-like proteins (RLPs). These RLPs recognize specific SSP effectors to initiate a hypersensitive response (HR) that renders the pathogen avirulent. C. fulvum strains capable of overcoming one or more of all cloned Cf genes have now emerged. To combat these strains, new Cf genes are required. An effectoromics approach was employed to identify wild tomato accessions carrying new Cf genes. Proteomics and transcriptome sequencing were first used to identify 70 apoplastic in planta-induced C. fulvum SSPs. Based on sequence homology, 61 of these SSPs were novel or lacked known functional domains. Seven, however, had predicted structural homology to antimicrobial proteins, suggesting a possible role in mediating antagonistic microbe-microbe interactions in planta. Wild tomato accessions were then screened for HR-associated recognition of 41 SSPs using the Potato virus X-based transient expression system. Nine SSPs were recognized by one or more accessions, suggesting that these plants carry new Cf genes available for incorporation into cultivated tomato.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Current Biology: Plant Autoimmunity: When Good Things Go Bad (2017)

Current Biology: Plant Autoimmunity: When Good Things Go Bad (2017) | Plants and Microbes | Scoop.it

A recent study finds that the Arabidopsis DM1 and DM2d proteins physically interact and trigger autoimmunity in plants. The DM1–DM2d interaction pattern differs from that of known immune receptor pairs, portraying the versatility in NLR functioning.

 

See Tran et al. Activation of a Plant NLR Complex through Heteromeric Association with an Autoimmune Risk Variant of Another NLR http://www.cell.com/current-biology/abstract/S0960-9822(17)30287-7

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Nature Microbiology: Stop neglecting fungi (2017)

Nature Microbiology: Stop neglecting fungi (2017) | Plants and Microbes | Scoop.it

Fungal pathogens are virtually ignored by the press, the public and funding bodies, despite posing a significant threat to public health, food biosecurity and biodiversity.

 

Fungal infections will probably not have made major news today, perhaps not even this week or month. Indeed, in comparison to the threat from drug-resistant bacterial infections or viral outbreaks, diseases caused by fungi, fungal drug resistance and the development of new antifungal therapeutics gets little coverage. Yet in this case, no news is certainly not good news, and the disparity relative to other infectious disease agents unjustified. The word fungus usually evokes images of athlete's foot, unseemly looking nails, or scrumptious cheese and mouth-watering mushrooms. However, few realize that over 300 million people suffer from serious fungal-related diseases, or that fungi collectively kill over 1.6 million people annually1, which is more than malaria and similar to the tuberculosis death toll. Fungi and oomycetes destroy a third of all food crops each year, which would be sufficient to feed 600 million people. Furthermore, fungal infestation of amphibians has led to the largest disease-caused loss of biodiversity ever recorded, while fungi also cause mass mortality of bats, bees and other animals, and decimate fruit orchards, pine, elm and chestnut forests2. Headline-grabbing statistics, one would imagine.

 

There are an estimated 1.5 million fungal species3, of which over 8,000 are known to cause disease in plants and 300 to be pathogenic to humans. Candida, Aspergillus, Pneumocystis and Cryptococcus spp. are the most common cause of serious disease in humans, and five fungal diseases — wheat stem rust, rice blast, corn smut, soybean fungi and potato late blight — are the most devastating for crop production. Infections primarily occur in immunocompromised patients, such as those undergoing chemotherapy or infected with HIV, and many are acquired in hospitals. However, infections of otherwise healthy people are on the rise. Global warming is inducing rapid poleward movement of crop fungal pathogens, and may also increase the prevalence of fungal disease in humans as fungi adapt to survival in warmer temperatures4. In this scenario, increasing resistance to the limited arsenal of antifungal drugs is a serious concern5, especially for Candida and Aspergillus infections, for which the therapeutic options have become limited. The emergence of multi-drug resistant Candida glabrata and Candida auris is a global health threat6, and azole-resistant Aspergillushas up to 30% prevalence in some European hospitals, which report higher than 90% mortality rates7.

Experts agree that fungal pathogens are a serious threat to human health, food biosecurity and ecosystem resilience, yet lack of funding translates into inadequate surveillance systems to monitor fungal disease incidence and antifungal drug resistance, which often rely on not-for-profit initiatives, such as the Global Action Fund for Fungal Infections (GAFFI; http://www.gaffi.org/). As highlighted in the World Health Organization (WHO) Global Report on Antimicrobial Resistance Surveillance8, which devotes fewer than 10% of its pages to fungi, resources allocated for monitoring and reducing antifungal drug resistance are limited. Indeed, the WHO has no funded programmes specifically targeting fungal diseases, fewer than 10 countries have national surveillance programs for fungal infections, and fewer than 20 have fungal reference diagnostic laboratories. Many of the diagnostic tests that do exist are not available in developing countries, and well-established antifungal drugs — such as amphotericin B, flucytosine and cotrim — that would cure disease do not reach people that need them, a large fraction of which are in sub-Saharan Africa9. In an attempt to tackle this silent humanitarian crisis, organizations such as GAFFI, the US Centres for Disease Control, Médecins Sans Frontières and Clinton Health Access lobbied to include amphotericin B and flucytosine on the WHO Essential Medicines List9. Beyond this, GAFFI has put forth a roadmap to achieve diagnosis and access to antifungals for 95% of infected people by 2025, which aims to improve the availability/affordability of diagnostics, train clinicians in fungal disease diagnosis and treatment, and ensure that antifungals are available globally10. Funding is also urgently needed to advance our understanding of fungal pathogenesis and drug resistance, develop new diagnostics and antifungal strategies, and improve monitoring of infection and antifungal resistance, as this will ultimately inform new strategies to tackle fungal infections.

 

Why then do fungi remain stubbornly off the mainstream radar? A possible reason is that most people think of fungi as causing infections that are uncomfortable but relatively easy to address, as invasive, life-threatening disease impacts few people in developed countries. In addition, our human-centric view of the world limits the amount of attention devoted to plant health, even if this directly impacts food availability. Bacteria and viruses have historically received more attention, in part because of the simple (yet not always correct) narrative to portray them as harmful, whereas fungi and their products can be edible, or useful drugs, and they are used as model organisms for understanding higher eukaryotes. Nevertheless, bringing emerging fungal threats into better focus for the broader research community, funders, media organizations and the general public should be a priority and will catalyse support and progress for this important and neglected group of pathogens.

 

Something that should make headlines this month, but may not, is the opening in South Africa of the AFGrica Unit in Medical Mycology, the first international research centre for tackling fungal infections (http://go.nature.com/2sN8x0z). This centre is an initiative of the University of Aberdeen Fungal Group (now the MRC Centre for Medical Mycology), in conjunction with the University of Cape Town. It will benefit from a Wellcome Trust Strategic Award that funds PhD students from developing nations to train in Aberdeen and other medical mycology centres and return home to help address fungal research and training needs. International collaborative efforts such as this one will be essential to give fungal diseases the prominence they require, and as such they should be encouraged. It is time to stop the neglect and put fungal diseases firmly in the spotlight.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

European conference on Xylella fastidiosa: finding answers to a global problem: Palma de Mallorca, 13-15 November 2017

European conference on Xylella fastidiosa: finding answers to a global problem: Palma de Mallorca, 13-15 November 2017 | Plants and Microbes | Scoop.it

A major scientific conference on European research into Xylella fastidiosa is to be held in Palma de Mallorca, Spain, from 13-15 November 2017. The conference is being organised jointly by EFSA, the University of the Balearic Islands, the Euphresconetwork for phytosanitary research coordination and funding, the EU Horizon 2020 projects POnTE and XF-ACTORS, and the European Commission’s Directorate-Generalfor Research and Innovation (DG RTD).

 

The event will provide a platform for in-depth discussion on the results of research into X. fastidiosa and its vectors, in support of on-going efforts to control the European outbreaks. As well as speakers and participants from Europe, the conference will be attended by scientific experts from other parts of the world – such as Brazil and the United States – where X. fastidiosa has been present for many years.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

International SPS Conference 2018: Plant Sciences for the Future, Paris July 4-6, 2018

International SPS Conference 2018: Plant Sciences for the Future, Paris July 4-6, 2018 | Plants and Microbes | Scoop.it
more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Science: Evolution of the wheat blast fungus through functional losses in a host specificity determinant (2017)

Science: Evolution of the wheat blast fungus through functional losses in a host specificity determinant (2017) | Plants and Microbes | Scoop.it

Wheat blast first emerged in Brazil in the mid-1980s and has recently caused heavy crop losses in Asia. Here we show how this devastating pathogen evolved in Brazil. Genetic analysis of host species determinants in the blast fungus resulted in the cloning of avirulence genes PWT3 and PWT4, whose gene products elicit defense in wheat cultivars containing the corresponding resistance genes Rwt3 and Rwt4. Studies on avirulence and resistance gene distributions, together with historical data on wheat cultivation in Brazil, suggest that wheat blast emerged due to widespread deployment of rwt3 wheat (susceptible to Lolium isolates), followed by the loss of function of PWT3. This implies that the rwt3 wheat served as a springboard for the host jump to common wheat.

 

See also: Caught in the jump http://science.sciencemag.org/content/357/6346/31

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

The Guardian: This new disease could devastate our wildlife (2017)

The Guardian: This new disease could devastate our wildlife (2017) | Plants and Microbes | Scoop.it

The less you care, the better you will do. This has long been the promise of conservative politics on both sides of the Atlantic. People who couldn’t give a tinker’s cuss about the consequences of their actions are elevated to the highest levels of government. Their role is to trash what lesser mortals value.

 

This describes the position of almost everyone in Donald Trump’s cabinet. In the UK, I feel it applies, among others, to Jeremy Hunt at the Department of Health, Boris Johnson at the Foreign Office, Priti Patel at international development and now Michael Gove at the environment department: the worst possible candidates are given the most sensitive portfolios.

 

Let me give you an example of how dangerous this appointment – and the government’s wider agenda – could be. A plant disease called Xylella fastidiosa, which originated in South America, is leaping across the European continent. It has now reached Italy, the Balearic Islands, Germany and France. As well as crops, it threatens many forest trees, including oak, elm, ash, cherry, sycamore and plane. Urban trees seem to be especially susceptible, perhaps because of the stresses they suffer: in American cities, some streets have had to be clear-felled. There is no known cure.

 

Xylella has ripped through olive groves in Italy and vineyards and fruit farms in the Americas. It is impossible to say how many species it might affect, how much damage it might do, and whether it would thrive in our climate. But we should hope we never find out.

 

It is unlikely to stay within the current European infection sites. Once the disease arrives, in imported plants, it is spread by sap-sucking insects, which can quickly be blown beyond the exclusion zones the EU has established. One of the few places that could remain unaffected is the UK, whose islands, Shakespeare remarked, are a “fortress built by Nature for herself against infection”. This blessed plot could become a reserve for species hammered by invasive diseases elsewhere.

 

But the government won’t contemplate it. Ignoring the pleas of foresters, scientists and some tree nurseries, the only measure it will apply is a “plant passport”. This will certify that potential hosts of the disease are free from infection before they are imported. There are 55 plants on its list. But already, according to the European Food Safety Authority, 359 plant species are known to carry the disease, in many cases without showing symptoms. They range across wildly different plant families, from magnolias to meadow grass, hydrangeas to holly, asparagus to aubergines, broad beans to buttercups, nettles to nightshade and lilac to lemon trees. New hosts are being discovered all the time. The only safe assumption is that almost any species could be a potential carrier.

 

In other words, the entire live plant trade presents a threat. The freedom with which it can move plants and the soil in which they are rooted across borders is a classic example of regulatory failure that has over the years spread hundreds of invasive species around the world. Unless there is a radical change of policy, the UK appears likely to repeat its grim experience with Dutch elm disease and ash dieback, but in this case potentially affecting far more species.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

MPMI: The tomato kinase Pti1 contributes to production of reactive oxygen species in response to two flagellin-derived peptides and promotes resistance to Pseudomonas syringae infection (2017)

MPMI: The tomato kinase Pti1 contributes to production of reactive oxygen species in response to two flagellin-derived peptides and promotes resistance to Pseudomonas syringae infection (2017) | Plants and Microbes | Scoop.it

The Pti1 kinase was identified from a reverse genetic screen as contributing to pattern-triggered immunity (PTI) against Pseudomonas syringae pv. tomato (Pst). This was unexpected because Pti1 was originally identified as an interactor of the Pto kinase and was implicated in effector-triggered immunity. The tomato genome has two Pti1 genes, referred to as Pti1a and Pti1b. A hairpin-Pti1 (hpPti1) construct was developed and used to generate two independent stable transgenic tomato lines, which had reduced transcript abundance of both genes. In response to Pst inoculation, these hpPti1 plants developed more severe disease symptoms, supported higher bacterial populations, and had reduced transcript accumulation of PTI-associated genes compared to wild-type plants. In response to two flagellin-derived peptides the hpPti1 plants produced less reactive oxygen species (ROS), but showed no difference in mitogen-activated protein kinase (MAPK). Synthetic Pti1a and Pti1bgenes designed to avoid silencing were transiently expressed in the hpPti1 plants and restored the ability of the plants to produce wild-type levels of ROS. Our results identify a new component of PTI in tomato which, because it affects ROS production but not MAPK signaling, appears to act early in the immune response.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Fourth Powdery Mildew School, Eger, Hungary, 9-13 September 2017

Fourth Powdery Mildew School, Eger, Hungary, 9-13 September 2017 | Plants and Microbes | Scoop.it

Eszterházy Károly University (Eger, Hungary), in collaboration with Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (Budapest, Hungary) and Centre for Crop Health, University of Southern Queensland (Toowoomba, Australia), invites MSc and PhD students and postdoc researchers interested in the study of powdery mildew fungi (Erysiphales) to an exciting autumn school covering all the major aspects of powdery mildew research. The official language of the course is English. This is the fourth Powdery Mildew School; the previous ones were organized in 2014, 2015 and 2016. Participants of the earlier workshops are welcome again in Eger.


The programme includes:

 

lectures on the morphology, phylogeny, genomics, host range, invasive patterns, host-pathogen interactions, and control of powdery mildews;

 

practical training in the classical and molecular identification of powdery mildews, quantification of infection levels, ascospore viability tests, and so on; the training activities will consist of hands-on experiments using light microscopy, including fluorescence techniques, DNA extractions from fresh and herbarium samples, PCR and qPCR methods, etc.;

 

discussion seminars on a number of recent and important papers; these will be presented by those participants who volunteer in advance to present a paper from the list of papers to be discussed in Eger.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Plant Cell: Interplay of Plasma Membrane and Vacuolar Ion Channels, Together with BAK1, Elicits Rapid Cytosolic Calcium Elevations in Arabidopsis during Aphid Feeding (2017)

Plant Cell: Interplay of Plasma Membrane and Vacuolar Ion Channels, Together with BAK1, Elicits Rapid Cytosolic Calcium Elevations in Arabidopsis during Aphid Feeding (2017) | Plants and Microbes | Scoop.it

A transient rise in cytosolic calcium ion concentration is one of the main signals used by plants in perception of their environment. The role of calcium in the detection of abiotic stress is well documented; however, its role during biotic interactions remains unclear. Here, we use a fluorescent calcium biosensor (GCaMP3) in combination with the green peach aphid (Myzus persicae) as a tool to study Arabidopsis thaliana calcium dynamics in vivo and in real time during a live biotic interaction. We demonstrate rapid and highly-localised plant calcium elevations around the feeding sites of M. persicae, and by monitoring aphid feeding behaviour electrophysiologically we demonstrate that these elevations correlate with aphid probing of epidermal and mesophyll cells. Furthermore, we dissect the molecular mechanisms involved, showing that interplay between the plant defence co-receptor BRASSINOSTEROID INSENSITIVE-ASSOCIATED KINASE 1 (BAK1), the plasma membrane ion channels GLUTAMATE RECEPTOR-LIKE 3.3 and 3.6 (GLR3.3 and GLR3.6) and the vacuolar ion channel TWO-PORE CHANNEL 1 (TPC1) mediate these calcium elevations. Consequently, we identify a link between plant perception of biotic threats by BAK1, cellular calcium entry mediated by GLRs, and intracellular calcium release by TPC1 during a biologically relevant interaction.

more...
No comment yet.
Rescooped by Kamoun Lab @ TSL from How microbes emerge
Scoop.it!

Science: Ecological and evolutionary effects of fragmentation on infectious disease dynamics (2014)

Science: Ecological and evolutionary effects of fragmentation on infectious disease dynamics (2014) | Plants and Microbes | Scoop.it

Ecological theory predicts that disease incidence increases with increasing density of host networks, yet evolutionary theory suggests that host resistance increases accordingly. To test the combined effects of ecological and evolutionary forces on host-pathogen systems, we analyzed the spatiotemporal dynamics of a plant (Plantago lanceolata)–fungal pathogen (Podosphaera plantaginis)relationship for 12 years in over 4000 host populations. Disease prevalence at the metapopulation level was low, with high annual pathogen extinction rates balanced by frequent (re-)colonizations. Highly connected host populations experienced less pathogen colonization and higher pathogen extinction rates than expected; a laboratory assay confirmed that this phenomenon was caused by higher levels of disease resistance in highly connected host populations.


Via Niklaus Grunwald
more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

Plant Cell: The RxLR Motif of the Host Targeting Effector AVR3a of Phytophthora infestans Is Cleaved Before Secretion (2017)

Plant Cell: The RxLR Motif of the Host Targeting Effector AVR3a of Phytophthora infestans Is Cleaved Before Secretion (2017) | Plants and Microbes | Scoop.it

When plant-pathogenic oomycetes infect their hosts, they employ a large arsenal of effector proteins to establish a successful infection. Some effector proteins are secreted and are destined to be translocated and function inside host cells. The largest group of translocated proteins from oomycetes are the RxLR effectors, defined by their conserved N-terminal Arg-Xaa-Leu-Arg (RxLR) motif. However, the precise role of this motif in the host cell translocation process is unclear. Here detailed biochemical studies of the RxLR effector AVR3a from the potato pathogen Phytophthora infestans are presented. Mass spectrometric analysis revealed that the RxLR sequence of native AVR3a is cleaved off prior to secretion by the pathogen and the N-terminus of the mature effector was found likely to be acetylated. High-resolution NMR structure analysis of AVR3a indicates that the RxLR motif is well accessible to potential processing enzymes. Processing and modification of AVR3a is to some extent similar to events occurring with the export element (PEXEL) found in malaria effector proteins from Plasmodium falciparum. These findings imply a role for the RxLR motif in the secretion of AVR3a by the pathogen, rather than a direct role in the host cell entry process itself.

more...
No comment yet.
Scooped by Kamoun Lab @ TSL
Scoop.it!

bioRxiv: Organ-Specific NLR Resistance Gene Expression Varies With Plant Symbiotic Status (2017)

bioRxiv: Organ-Specific NLR Resistance Gene Expression Varies With Plant Symbiotic Status (2017) | Plants and Microbes | Scoop.it

Nucleotide-binding site leucine-rich repeat resistance genes (NLRs) allow plants to detect microbial effectors. We hypothesized that NLR expression patterns would reflect organ-specific differences in effector challenge and tested this by carrying out a meta-analysis of expression data for 1,235 NLRs from 9 plant species. We found stable NLR root/shoot expression ratios within species, suggesting organ-specific hardwiring of NLR expression patterns in anticipation of distinct challenges. Most monocot and dicot plant species preferentially expressed NLRs in roots. In contrast, Brassicaceae species, including oilseed rape and the model plant Arabidopsis thaliana, were unique in showing NLR expression skewed towards the shoot across multiple phylogenetically distinct groups of NLRs. The Brassicaceae NLR expression shift coincides with loss of the endomycorrhization pathway, which enables intracellular root infection by symbionts. We propose that its loss offer two likely explanations for the unusual Brassicaceae NLR expression pattern: loss of NLR-guarded symbiotic components and elimination of constraints on general root defences associated with exempting symbionts from targeting. This hypothesis is consistent with the existence of Brassicaceae-specific receptors for conserved microbial molecules and suggests that Brassicaceae species could be rich sources of unique antimicrobial root defence mechanisms.

more...
No comment yet.
Rescooped by Kamoun Lab @ TSL from Plant pathogens and pests
Scoop.it!

New Phytologist: A small secreted protein in Zymoseptoria tritici is responsible for avirulence on wheat cultivars carrying the Stb6 resistance gene (2016)

New Phytologist: A small secreted protein in Zymoseptoria tritici is responsible for avirulence on wheat cultivars carrying the Stb6 resistance gene (2016) | Plants and Microbes | Scoop.it
  • Zymoseptoria tritici is the causal agent of Septoria tritici blotch, a major pathogen of wheat globally and the most damaging pathogen of wheat in Europe. A gene-for-gene (GFG) interaction between Z. tritici and wheat cultivars carrying the Stb6resistance gene has been postulated for many years, but the genes have not been identified.
  • We identified AvrStb6 by combining quantitative trait locus mapping in a cross between two Swiss strains with a genome-wide association study using a natural population of c. 100 strains from France. We functionally validated AvrStb6 using ectopic transformations.
  • AvrStb6 encodes a small, cysteine-rich, secreted protein that produces an avirulence phenotype on wheat cultivars carrying the Stb6 resistance gene. We found 16 nonsynonymous single nucleotide polymorphisms among the tested strains, indicating that AvrStb6 is evolving very rapidly. AvrStb6 is located in a highly polymorphic subtelomeric region and is surrounded by transposable elements, which may facilitate its rapid evolution to overcome Stb6 resistance.
  • AvrStb6 is the first avirulence gene to be functionally validated in Z. tritici, contributing to our understanding of avirulence in apoplastic pathogens and the mechanisms underlying GFG interactions between Z. tritici and wheat.

 


Via Christophe Jacquet
more...
No comment yet.