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BBSRC Feature: Using their genes against them: Fighting insect pests with genetic targeting (2013)

BBSRC Feature: Using their genes against them: Fighting insect pests with genetic targeting (2013) | Plants and Microbes | Scoop.it

When you look out on a golden-yellow field of oilseed rape you might not think you're seeing a battleground, but crops including oilseed rape, wheat, potato and tomato are engaged in a constant fight with pests and disease, trying to stay one step ahead.

As the world's human population looks set to increase to nine billion people by 2050, keeping plants healthy and productive is going to be essential to making sure there is enough food to go round.Aphids damage crops by feeding on them and transmitting plant diseases. "Crop pests are emerging earlier due to global warming and new variants are arriving from other countries, bringing new plant viruses", said Dr Saskia Hogenhout from the John Innes Centre (JIC) in Norwich, an institute strategically funded by the BBSRC.

 

Among these pests whitefly and green peach aphids cause hundreds of millions of pounds of damage and loss to crops through transmitting viruses and feeding. Both species are notorious for demonstrating the ability to rapidly develop resistance to conventional pesticides, and both attack a wide variety of crops, including cabbage, lettuce, beet, oilseed rape and potato. In UK cereal crops aphids alone can cause yield losses of over 40 per cent, and insect pests are responsible for an estimated 15 per cent of all crop losses globally. Dr Hogenhout said: "The aphids and whitefly themselves are problematic but they also transmit more than half of all plant viruses. They're called the mosquitoes of plants because like mosquitoes they feed on the vascular system and they transmit quite a number of viruses."

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Knapco's curator insight, January 12, 2013 2:57 PM

Very promissing non-chemical method to combath aphid and whitefly species in the future! Whiteflies suffer from an identity crisis, as they are not flies at all, in appearance they resemble tiny, pure white 'moths' but are in fact, closely related to sap-sucking aphids. Aphids and whiteflies can both cause severe damage to wide range of crops by sucking sap from the plant, resulting in damages of the leaves, as well as leaf loss, wilting and stunting. Not only do they feed on plants, but they also produce honeydew, which spoils the plants' appearance, attracts ants and black sooty mould. Both can also transmit different species of plant viruses, which cause further damage to crops. Until the gene silencing methods are applied, biologocial control could be used as alternative to insecticide's use.

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BES Symposium: The Ecology and Evolution of Emerging Plant Pests and Pathogens: Challenges to Global Food Security and Ecosystem Resilience, 13–14 July, 2015, Cornwall, UK

BES Symposium: The Ecology and Evolution of Emerging Plant Pests and Pathogens: Challenges to Global Food Security and Ecosystem Resilience, 13–14 July, 2015, Cornwall, UK | Plants and Microbes | Scoop.it
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MPMI: A recent expansion of the RXLR effector gene Avrblb2 is maintained in global populations of Phytophthora infestans indicating different contributions to virulence (2015)

MPMI: A recent expansion of the RXLR effector gene Avrblb2 is maintained in global populations of Phytophthora infestans indicating different contributions to virulence (2015) | Plants and Microbes | Scoop.it

The introgression of disease resistance (R) genes encoding immunoreceptors with broad-spectrum recognition into cultivated potato appears to be the most promising approach to achieve sustainable management of late blight caused by the oomycete pathogen Phytophthora infestans. Rpi-blb2 from Solanum bulbocastanum, shows great potential for use in agriculture based on preliminary potato disease trials. Rpi-blb2 confers immunity by recognizing the P. infestans avirulence effector protein AVRblb2 after it is translocated inside the plant cell. This effector belongs to the RXLR class of effectors and is under strong positive selection. Structure-function analyses revealed a key polymorphic amino acid (position 69) in AVRblb2 effector that is critical for activation of Rpi-blb2. In this study, we reconstructed the evolutionary history of the Avrblb2 gene family and further characterized its genetic structure in worldwide populations. Our data indicates that Avrblb2 evolved as a single copy gene in a putative ancestral species of P. infestans and has recently expanded in the Phytophthora species that infect solanaceous hosts. As a consequence, at least four variants of AVRblb2 arose in P. infestans. One of these variants, with a Phe residue at position 69, evades recognition by the cognate resistance gene. Surprisingly, all Avrblb2 variants are maintained in pathogen populations. This suggests a potential benefit for the pathogen in preserving duplicated versions of AVRblb2 possibly because the variants may have different contributions to pathogen fitness in a diversified solanaceous host environment.

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Plant Cell: A Secreted Effector Protein of Ustilago maydis Guides Maize Leaf Cells to Form Tumors (2015)

Plant Cell: A Secreted Effector Protein of Ustilago maydis Guides Maize Leaf Cells to Form Tumors (2015) | Plants and Microbes | Scoop.it

The biotrophic smut fungus Ustilago maydis infects all aerial organs of maize (Zea mays) and induces tumors in the plant tissues. U. maydis deploys many effector proteins to manipulate its host. Previously, deletion analysis demonstrated that several effectors have important functions in inducing tumor expansion specifically in maize leaves. Here, we present the functional characterization of the effector See1 (Seedling efficient effector1). See1 is required for the reactivation of plant DNA synthesis, which is crucial for tumor progression in leaf cells. By contrast, See1 does not affect tumor formation in immature tassel floral tissues, where maize cell proliferation occurs independent of fungal infection. See1 interacts with a maize homolog of SGT1 (Suppressor of G2 allele of skp1), a factor acting in cell cycle progression in yeast (Saccharomyces cerevisiae) and an important component of plant and human innate immunity. See1 interferes with the MAPK-triggered phosphorylation of maize SGT1 at a monocot-specific phosphorylation site. We propose that See1 interferes with SGT1 activity, resulting in both modulation of immune responses and reactivation of DNA synthesis in leaf cells. This identifies See1 as a fungal effector that directly and specifically contributes to the formation of leaf tumors in maize.

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4th International Conference on Biotic Plant Interactions, Nanjing, Jiangsu, China, Aug 1-3, 2015.

4th International Conference on Biotic Plant Interactions, Nanjing, Jiangsu, China, Aug 1-3, 2015. | Plants and Microbes | Scoop.it

Plants constantly interact with a wide range of microbes and insects. These interactions, which can be beneficial or harmful to plants, influence greatly on agricultural production and our daily life. On behalf of the steering committee, it is our pleasure to invite colleagues in the fields of biotic plant interactions to attend the 4th International Conference on Biotic Plant Interactions, which will be held at Nanjing, Jiangsu, China, on Aug 1-3, 2015.


The theme of this 3-day meeting is Biotic Plant Interactions and Agricultural Production. As a continuing effort after the 1st conference held in Brisbane, Australia, 2008, 2nd conference held in Kunming, China, 2011, and 3rd conference held in Yangling, China, 2013, this meeting will cover a wide range of scientific research topics spanning Plant Pathology, Plant-Microbe Interactions, Plant-Insect interactions, Pathogen and Insect Genomics and Molecular Evolution, and Biotechnology on disease and insect resistance. This conference will bring together scientists and students who are interested in plant pathology and beneficial interactions of plants with other organisms, including viruses, bacteria, fungi, oomycetes, nematodes, insects and other herbivores, and genomics and evolution of pathogens and insects.


We are looking forward to welcoming you in Nanjing, China.


Sincerely Yours!


Yuanchao Wang & Zuhua He


Chairmans of the Organizing Committee

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eLife: Natural genetic variation in Arabidopsis thaliana defense metabolism genes modulates field fitness (2015)

eLife: Natural genetic variation in Arabidopsis thaliana defense metabolism genes modulates field fitness (2015) | Plants and Microbes | Scoop.it

Natural populations persist in complex environments, where biotic stressors, such as pathogen and insect communities, fluctuate temporally and spatially. These shifting biotic pressures generate heterogeneous selective forces that can maintain standing natural variation within a species. To directly test if genes containing causal variation for the Arabidopsis thaliana defensive compounds, glucosinolates (GSL) control field fitness and are therefore subject to natural selection, we conducted a multi-year field trial using lines that vary in only specific causal genes. Interestingly, we found that variation in these naturally polymorphic GSL genes affected fitness in each of our environments but the pattern fluctuated such that highly fit genotypes in one trial displayed lower fitness in another and that no GSL genotype or genotypes consistently out-performed the others. This was true both across locations and within the same location across years. These results indicate that environmental heterogeneity may contribute to the maintenance of GSL variation observed within Arabidopsis thaliana.

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The Conversation: The cutting-edge science taking on some of the world's most notorious parasitic plants (2015)

The Conversation: The cutting-edge science taking on some of the world's most notorious parasitic plants (2015) | Plants and Microbes | Scoop.it
Little is known about how parasitic plants live side-by-side with their hosts. But new genetic techniques may help scientists gain further insights.


Thousands of plant species have adopted a “parasitic” mode of life, living off a host plant which supplies it with water and nutrients. Most of these remain harmless, but a few have evolved to become serious agricultural weeds that threaten food security in some of the world’s poorest regions.

Parasitic plants are deceptively common, you have probably come across the snarling strands of Dodder – a stem parasite which infects nettles – in a local hedgerow. Even the world’s largest flower, Rafflesia arnoldii, found in the rainforests of South-East Asia, is a parasite, infecting and living off tropical vines.

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ASPB News: 2015 Charles Albert Shull Award Winner: Dr. Cyril Zipfel

ASPB News: 2015 Charles Albert Shull Award Winner: Dr. Cyril Zipfel | Plants and Microbes | Scoop.it

Cyril Zipfel, who heads The Sainsbury Laboratory, is the 2015 recipient of the Charles Albert Shull Award. Cyril played a leading role in the discovery of pattern-triggered immunity in plants, including the characterization of the bacterial peptides flagellin (flg22) and EF-Tu (elf18) as pattern-associated molecular markers that activate signaling by the receptor-like kinases FLS2 and EFR, respectively, leading to plant immunity. He found that the brassinosteroid co-receptor, BAK1, also cooperates with 2 FLS2 and EFR, and he identified residues of BAK1 that are key to specifying co-receptor output toward brassinosteroid signaling, cell death control, or innate immunity. Cyril also made the major practical discovery that transgenic expression of Arabidopsis EFR in Solanaceous species, which normally do not recognize the bacterial ligand EF-Tu, confers immunity to a broad range of bacteria, and he has extended this approach to cereals. Honors will be presented at the Plant Biology 2015 meeting in Minneapolis. You can read the full list of 2015 ASPB awardees on the ASPB website.

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Euro J. Biochem: Structure and activity of proteins from pathogenic fungi Phytophthora eliciting necrosis and acquired resistance in tobacco (1989)

Euro J. Biochem: Structure and activity of proteins from pathogenic fungi Phytophthora eliciting necrosis and acquired resistance in tobacco (1989) | Plants and Microbes | Scoop.it

The phytopathogenic fungi Phytophthora cryptogea and Phytophthora capsici cause systemic leaf necrosis on their non-host tobacco; in culture they release proteins, called cryptogein and capsicein, which elicit similar necrosis. In addition, both proteins protect tobacco against invasion by the pathogen Phytophthora nicotianae, the agent of the tobacco black shank, that is unable to produce such an elicitor. Cryptogein causes visible leaf necrosis starting at about 1 μg/plant, whereas 50-fold as much capsicein is required for the same reaction. Capsicein induces protection even in near absence of leaf necrosis. The activities of both elicitors are eliminated upon pronase digestion. They are proteins of similar Mr (respectively 10323 and 10155) and their complete amino acid sequences were determined. They consist of 98 residues, with some internal repetitions of hexapeptides and heptapeptides. 85% identity was observed between both sequences: only two short terminal regions are heterologous, while the central core is entirely conserved. Secondary structure predictions, hydropathy and flexibility profiles differ only around position 15 and at the C-terminus; these modifications could play a role in the modulation of their biological activities. After a search of the sequence data bases, they appear to be novel proteins.

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#JGI2015 Day 3 of 10th Annual DOE Joint Genome Institute Genomics of Energy & Environment Meeting (with images, tweets)

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#JGI2015 Days 1/2 of 10th Annual DOE Joint Genome Institute Genomics of Energy & Environment Meeting, March 2015 (with images, tweets)

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Frontiers: Silver linings: a personal memoir about Hurricane Katrina and fungal volatiles (2015)

Frontiers: Silver linings: a personal memoir about Hurricane Katrina and fungal volatiles (2015) | Plants and Microbes | Scoop.it

In the aftermath of Hurricane Katrina, the levees protecting New Orleans, Louisiana failed. Because approximately 80% of the city was under sea level, widespread flooding ensued. As a resident of New Orleans who had evacuated before the storm and a life-long researcher on filamentous fungi, I had known what to expect. After the hurricane I traveled home with a suitcase full of Petri dishes and sampling equipment so as to study the fungi that were “eating my house.” Not only were surfaces covered with fungal growth, the air itself was full of concentrated mold odor, a smell that was orders of magnitude more funky than any damp, musty basement I had ever encountered. The smell made me feel bad and I had to take regular breaks as I sampled. Being a mycotoxin expert, I knew a fair amount about “sick building syndrome” but believed that it was difficult to get enough respiratory exposure to toxins to cause the array of symptoms associated with the syndrome. So why was I feeling sick? Some Scandinavian experts had hypothesized that mold volatile organic compounds (VOCs) might be the fungal metabolites to blame for sick building syndrome and the time in my smelly, mold infested home made me think they might be right. After securing a new job and establishing a new laboratory, I endeavored to test the hypothesis that some volatile mold metabolites might be toxic. My laboratory at Rutgers University has interrogated the role of VOCs in possible interkingdom toxicity by developing controlled microcosms for exposing simple genetic model organisms to the vapor phase of growing fungi. Both Arabidopsis thaliana and Drosophila melanogaster exhibit a range of toxic symptoms that vary with the species of fungus, the duration of exposure, and other experimental parameters. Moreover, low concentrations of chemical standards of individual fungal VOCs such as 1-octen-3-ol also exhibit varying toxicity and cause neurotoxicity in a Drosophila model. Collectively, these data suggest that fungal VOCs may contribute to some of the adverse health effects reported by people exposed to damp indoor environments and that biogenic gas phase molecules deserve increased attention by the research community.

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New Phytologist: Plants, fungi and oomycetes: a 400-million year affair that shapes the biosphere (2015)

New Phytologist: Plants, fungi and oomycetes: a 400-million year affair that shapes the biosphere (2015) | Plants and Microbes | Scoop.it

In a rare gathering, genomics met palaeontology at the 10th New Phytologist Workshop on the ‘Origin and evolution of plants and their interactions with fungi’. An eclectic group of 17 experts met at The Natural History Museum (London, UK) on 9–10 September 2014 to discuss the latest findings on plant interactions with fungi (Eumycota) and oomycetes (Oomycota = Peronosporomycota), with topics ranging from the fossil record and comparative genomics to symbiosis and phytopathology. The discussions were largely disseminated via social media (Box 1). Highly diverse plant–fungal interactions have formed the backbone of land ecosystems and biogeochemical cycles since the Palaeozoic (see Fig. 1 for geological timeframe). As summarized by Christine Strullu-Derrien and Paul Kenrick (The Natural History Museum, London, UK) the first land plants arose c. 470 million years (Myr) ago (Kenrick et al., 2012; Edwards et al., 2014), at which time fungi and oomycetes had already colonized terrestrial ecosystems. Following their terrestrialization, these microbes began to abound within plant fossils (Taylor et al., 2014, and references therein). Ultimately, biological interactions sculpted the genomes of plants, fungi and oomycetes (e.g. Schmidt & Panstruga, 2011; Kohler et al., 2015). Here we illustrate the picture that has emerged from the discussions at the 10th New Phytologist Workshop, and point to some pending questions.


Via Francis Martin
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Pierre-Marc Delaux's curator insight, March 23, 5:54 AM

It was a great workshop indeed!

Peter Buckland's curator insight, March 23, 9:01 AM

The importance of plant-fungal interactions

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Molecular Plant Pathology: A new look at plant viruses and their potential beneficial roles in crops (2015)

Molecular Plant Pathology: A new look at plant viruses and their potential beneficial roles in crops (2015) | Plants and Microbes | Scoop.it

Twenty years ago most people (including many scientists) thought of bacteria solely as agents of disease, best treated with disinfectants and antibiotics. Today, most of us are aware that bacteria make up almost 90% of the cells in our bodies, and play a critical role in digestion and the immune response. In plants, bacteria also form important mutualistic relationships, providing nitrogen fixation, growth enhancement and defence against pathogens, and undoubtedly a host of other functions that have yet to be described. The stigma of bacteria has changed dramatically in recent decades, and most people are aware that we need our good microbes.


Although there have been recent efforts to characterize the plant microbiome with a focus on finding beneficial microbes, viruses generally have not been included in the beneficial microbe lists (Berg et al., 2014, and references cited therein). Recent work has indicated that they can also play important and beneficial roles in plants, especially in extreme environments in which they are involved in conferring tolerance to drought, cold and hot soil temperatures (Roossinck, 2011). Beneficial viruses are defined for the purposes of this discussion as viruses that provide a trait to crop plants that increases their value or growth potential, or decreases the need for the use of chemical fertilizers or pesticides.


See also http://www.noble.org/ag/research/microbes/

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PNAS: The genome of cultivated sweet potato contains Agrobacterium T-DNAs with expressed genes: An example of a naturally transgenic food crop (2015)

PNAS: The genome of cultivated sweet potato contains Agrobacterium T-DNAs with expressed genes: An example of a naturally transgenic food crop (2015) | Plants and Microbes | Scoop.it

Agrobacterium rhizogenes and Agrobacterium tumefaciens are plant pathogenic bacteria capable of transferring DNA fragments [transfer DNA (T-DNA)] bearing functional genes into the host plant genome. This naturally occurring mechanism has been adapted by plant biotechnologists to develop genetically modified crops that today are grown on more than 10% of the world’s arable land, although their use can result in considerable controversy. While assembling small interfering RNAs, or siRNAs, of sweet potato plants for metagenomic analysis, sequences homologous to T-DNA sequences from Agrobacterium spp. were discovered. Simple and quantitative PCR, Southern blotting, genome walking, and bacterial artificial chromosome library screening and sequencing unambiguously demonstrated that two different T-DNA regions (IbT-DNA1 and IbT-DNA2) are present in the cultivated sweet potato (Ipomoea batatas [L.] Lam.) genome and that these foreign genes are expressed at detectable levels in different tissues of the sweet potato plant. IbT-DNA1 was found to contain four open reading frames (ORFs) homologous to the tryptophan-2-monooxygenase (iaaM), indole-3-acetamide hydrolase (iaaH), C-protein (C-prot), and agrocinopine synthase (Acs) genes of Agrobacterium spp. IbT-DNA1 was detected in all 291 cultigens examined, but not in close wild relatives. IbT-DNA2 contained at least five ORFs with significant homology to the ORF14, ORF17n, rooting locus (Rol)B/RolC, ORF13, and ORF18/ORF17n genes of A. rhizogenes. IbT-DNA2 was detected in 45 of 217 genotypes that included both cultivated and wild species. Our finding, that sweet potato is naturally transgenic while being a widely and traditionally consumed food crop, could affect the current consumer distrust of the safety of transgenic food crops.

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PNAS: Phytophthora effector targets a novel component of small RNA pathway in plants to promote infection (2015)

PNAS: Phytophthora effector targets a novel component of small RNA pathway in plants to promote infection (2015) | Plants and Microbes | Scoop.it

Phytophthora is a major threat to agriculture. However, the molecular interaction of these severe pathogens with plant hosts is poorly understood. Here, we report that the Phytophthora Suppressor of RNA Silencing 1 (PSR1) effectively promotes infection in Arabidopsis thaliana by directly targeting an essential protein containing a aspartate–glutamate–alanine–histidine-box RNA helicase domain. This PSR1-Interacting Protein 1 (PINP1) is required for the accumulation of distinct classes of endogenous small RNAs and acts as a positive regulator of plant immunity. Silencing of PINP1 impaired the assembly of microRNA-processing complexes in the nucleus, leading to defects in development and immunity. This study revealed a conserved RNA helicase as a regulator of RNA silencing and provides mechanistic insight into Phytophthora pathogenesis.

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The New Yorker: We Have No Bananas - Can scientists defeat a devastating blight? (2015)

The New Yorker: We Have No Bananas - Can scientists defeat a devastating blight? (2015) | Plants and Microbes | Scoop.it

Darwin, the capital of Australia’s Northern Territory, is more than a thousand miles northwest of the country’s largest banana plantations, which are centered around Innisfail, on the eastern seaboard. A ramshackle place, Darwin is known for its many impoverished indigenous residents, entertainment attractions like Crocosaurus Cove (where visitors are lowered, via “the Cage of Death,” into a crocodile-filled tank), and, as one local puts it, “not partying, exactly, but certainly drinking.” To Robert Borsato, a fruit farmer, the area looked like an ideal place to grow bananas. In 1996, he began farming a thousand acres in Humpty Doo, which is on the road between Darwin and Kakadu National Park.


To bear fruit, banana plants need at least fourteen consecutive months of frost-free weather, which is why they are not grown commercially in the continental United States. Darwin offered this, and more. As one of Borsato’s workers told me recently, “You came up here and saw the consistency that you’ve got between the blue sky, the sunshine, the water, the fucking soil. You knew you were going to beat everybody else, hands down.” There were a few nuisances: crocodiles wandered onto the property, Asian buffalo trampled young plants, and dingoes chewed the sprinklers. Before long, though, the Darwin Banana Farming Company was growing lush ten-foot plants with as many as a hundred and seventy bananas on each stalk. In 2006, Cyclone Larry decimated ninety per cent of the Innisfail plantations; banana prices soared from ten dollars a carton to a hundred and thirty, and Borsato became a multimillionaire.


More than a thousand kinds of banana can be found worldwide, but Borsato specialized in a variety called Cavendish, which a nineteenth-century British explorer happened upon in a household garden in southern China. Today, the Cavendish represents ninety-nine per cent of the banana export market. The vast majority of banana varieties are not viable for international trade: their bunches are too small, or their skin is too thin, or their pulp is too bland. Although Cavendishes need pampering, they are the only variety that provides farmers with a high yield of palatable fruit that can endure overseas trips without ripening too quickly or bruising too easily. The Cavendish, which is rich in Vitamins B6 and C, has high levels of potassium, magnesium, and fibre; it is also cheap—about sixty cents a pound. In 2008, Americans ate 7.6 billion pounds of Cavendish bananas, virtually all of them imported from Latin America. Each year, we eat as many Cavendish bananas as we do apples and oranges combined. Your supermarket likely sells many varieties of apples, but when you shop for bananas you usually have one option. The world’s banana plantations are a monoculture of Cavendishes.


Several years ago, Borsato noticed a couple of sick-looking plants on a neighbor’s property. The leaves turned a soiled yellow, starting at the edges and rapidly moving inward; necrotic patches appeared and, a few weeks later, the leaves buckled. What had once formed a canopy now dangled around the base of the plant, like a cast-off grass skirt. Inside the plant, the effects were even worse. Something was blocking the plants’ vascular system, causing rot, and tissue that should have been as ivory as the inside of a celery stalk was a putrefying mixture of brown, black, and blood-red. When the plants were cut open, they smelled like garbage, and their roots were so anemic that the plants could barely stay upright.


Borsato feared that he was seeing the symptoms of a pestilence that had wiped out the Cavendish across Asia: Tropical Race Four. A soil-borne fungus that is known to be harmful only to bananas, it can survive for decades in the dirt, spreading through the transportation of tainted plants, or in infected mud stuck to a tractor’s tire or a rancher’s boot. It cannot be controlled with chemicals. Tropical Race Four appeared in Taiwan in the late eighties, and destroyed roughly seventy per cent of the island’s Cavendish plantations. In Indonesia, more than twelve thousand acres of export bananas were abandoned; in Malaysia, a local newspaper branded the disease “the H.I.V. of banana plantations.” When the fungus reached China and the Philippines, the effect was equally ruinous.


[Fusarium oxysporum f. sp. cubense TR4]

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New Phytologist: The tomato I-3 gene: a novel gene for resistance to Fusarium wilt disease - Catanzariti (2015)

New Phytologist: The tomato I-3 gene: a novel gene for resistance to Fusarium wilt disease - Catanzariti (2015) | Plants and Microbes | Scoop.it
  • Plant resistance proteins provide race-specific immunity through the recognition of pathogen effectors. The resistance genes I, I-2 and I-3 have been incorporated into cultivated tomato (Solanum lycopersicum) from wild tomato species to confer resistance against Fusarium oxysporum f. sp. lycopersici (Fol) races 1, 2 and 3, respectively. Although the Fol effectors corresponding to these resistance genes have all been identified, only the I-2 resistance gene has been isolated from tomato.
  • To isolate the I-3 resistance gene, we employed a map-based cloning approach and used transgenic complementation to test candidate genes for resistance to Fol race 3.
  • Here, we describe the fine mapping and sequencing of genes at the I-3 locus, which revealed a family of S-receptor-like kinase (SRLK) genes. Transgenic tomato lines were generated with three of these SRLK genes and one was found to confer Avr3-dependent resistance to Fol race 3, confirming it to be I-3.
  • The finding that I-3 encodes an SRLK reveals a new pathway for Fol resistance and a new class of resistance genes, of which Pi-d2from rice is also a member. The identification of I-3 also allows the investigation of the complex effector–resistance protein interaction involving Avr1-mediated suppression of I-2- and I-3-dependent resistance in tomato.
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New Phytologist: Tissue-specific FLAGELLIN-SENSING 2 (FLS2) expression in roots restores immune responses in Arabidopsis fls2 mutants (2015)

New Phytologist: Tissue-specific FLAGELLIN-SENSING 2 (FLS2) expression in roots restores immune responses in Arabidopsis fls2 mutants (2015) | Plants and Microbes | Scoop.it
  • The flagellin receptor of Arabidopsis, At-FLAGELLIN SENSING 2 (FLS2), has become a model for mechanistic and functional studies on plant immune receptors. Responses to flagellin or its active epitope flagellin 22 (flg22) have been extensively studied in Arabidopsis leaves. However, the perception of microbe-associated molecular patterns (MAMPs) and the immune responses in roots are poorly understood.
  • Here, we show that isolated root tissue is able to induce pattern-triggered immunity (PTI) responses upon flg22 perception, in contrast to elf18 (the active epitope of elongation factor thermo unstable (EF-Tu)). Making use of fls2 mutant plants and tissue-specific promoters, we generated transgenic Arabidopsis lines expressing FLS2 only in certain root tissues. This allowed us to study the spatial requirements for flg22 responses in the root.
  • Remarkably, the intensity of the immune responses did not always correlate with the expression level of the FLS2 receptor, but depended on the expressing tissue, supporting the idea that MAMP perception and sensitivity in different tissues contribute to a proper balance of defense responses according to the expected exposure to elicitors.
  • In summary, we conclude that each investigated root tissue is able to perceive flg22 if FLS2 is present and that tissue identity is a major element of MAMP perception in roots.
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ASPB News: 2015 Dennis R. Hoagland Award Winner: Dr. Maria Harrison

ASPB News: 2015 Dennis R. Hoagland Award Winner: Dr. Maria Harrison | Plants and Microbes | Scoop.it

Dr. Maria Harrison, Boyce Thompson Institute for Plant Science, has pioneered studies of phosphate acquisition in arbuscular mycorrhizal (AM) symbioses using the model legume Medicago truncatula. In particular, her findings that phosphate transport is linked to maintenance of symbiosis and that plants use classic hormone signaling pathways for regulation of the AM symbiosis have ushered the field of fungal–plant interactions in new directions, and they provide opportunities for the future manipulation of phosphate acquisition in crop species. Maria has identified key gene products required for phosphate transport and uptake, and she has shown that redirected plant protein secretion mechanisms target transporters to symbiotic membranes. Maria has also has developed cell biology resources for in vivo cellular imaging in Medicago that expand research capabilities to further unravel the nutritional function of the AM symbiosis. The Hoagland award is given in recognition of her outstanding contributions to plant mineral nutrition. Honors will be presented at the Plant Biology 2015 meeting in Minneapolis. You can read the full list of 2015 ASPB awardees on the ASPB website.


Via Jean-Michel Ané, Pierre-Marc Delaux
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New Phytologist: Immune activation mediated by the late blight resistance protein R1 requires nuclear localization of R1 and the effector AVR1 (2015)

New Phytologist: Immune activation mediated by the late blight resistance protein R1 requires nuclear localization of R1 and the effector AVR1 (2015) | Plants and Microbes | Scoop.it
  • Resistance against oomycete pathogens is mainly governed by intracellular nucleotide-binding leucine-rich repeat (NLR) receptors that recognize matching avirulence (AVR) proteins from the pathogen, RXLR effectors that are delivered inside host cells. Detailed molecular understanding of how and where NLR proteins and RXLR effectors interact is essential to inform the deployment of durable resistance (R) genes.
  • Fluorescent tags, nuclear localization signals (NLSs) and nuclear export signals (NESs) were exploited to determine the subcellular localization of the potato late blight protein R1 and the Phytophthora infestans RXLR effector AVR1, and to target these proteins to the nucleus or cytoplasm.
  • Microscopic imaging revealed that both R1 and AVR1 occurred in the nucleus and cytoplasm, and were in close proximity. Transient expression of NLS- or NES-tagged R1 and AVR1 in Nicotiana benthamiana showed that activation of the R1-mediated hypersensitive response and resistance required localization of the R1/AVR1 pair in the nucleus. However, AVR1-mediated suppression of cell death in the absence of R1 was dependent on localization of AVR1 in the cytoplasm. Balanced nucleocytoplasmic partitioning of AVR1 seems to be a prerequisite.
  • Our results show that R1-mediated immunity is activated inside the nucleus with AVR1 in close proximity and suggest that nucleocytoplasmic transport of R1 and AVR1 is tightly regulated.
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Nature Plants: Elicitin recognition confers enhanced resistance to Phytophthora infestans in potato (2015)

Nature Plants: Elicitin recognition confers enhanced resistance to Phytophthora infestans in potato (2015) | Plants and Microbes | Scoop.it

Potato late blight, caused by the destructive Irish famine pathogen Phytophthora infestans, is a major threat to global food security1,2. All late blight resistance genes identified to date belong to the coiled-coil, nucleotide-binding, leucine-rich repeat class of intracellular immune receptors3. However, virulent races of the pathogen quickly evolved to evade recognition by these cytoplasmic immune receptors4. Here we demonstrate that the receptor-like protein ELR (elicitin response) from the wild potato Solanum microdontum mediates extracellular recognition of the elicitin domain, a molecular pattern that is conserved in Phytophthora species. ELR associates with the immune co-receptor BAK1/SERK3 and mediates broad-spectrum recognition of elicitin proteins from several Phytophthora species, including four diverse elicitins from P. infestans. Transfer of ELR into cultivated potato resulted in enhanced resistance to P. infestans. Pyramiding cell surface pattern recognition receptors with intracellular immune receptors could maximize the potential of generating a broader and potentially more durable resistance to this devastating plant pathogen.

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Phytobiomes 2015: Designing a New Paradigm for Crop Improvement​​​​​​​​​​​​​​​​​​​​​​, June 30–J​uly 2, 2015, Washington, DC, U.S.A.​

Phytobiomes 2015: Designing a New Paradigm for Crop Improvement​​​​​​​​​​​​​​​​​​​​​​, June 30–J​uly 2, 2015, Washington, DC, U.S.A.​ | Plants and Microbes | Scoop.it

Phytobiomes 2015: Designing a New Paradigm for Crop Improvement brings together renowned experts in diverse fields related to phytobiomes with sessions ranging from the lessons that can be learned from other microbiome efforts to designing a path forward for a phytobiomes systems approach. Plan now to attend these 2 ½ days encompassing plenary speakers, discussions, and posters presentations.

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PLOS Genetics: The Evolution of Fungal Metabolic Pathways (2014)

PLOS Genetics: The Evolution of Fungal Metabolic Pathways (2014) | Plants and Microbes | Scoop.it

Fungi contain a remarkable range of metabolic pathways, sometimes encoded by gene clusters, enabling them to digest most organic matter and synthesize an array of potent small molecules. Although metabolism is fundamental to the fungal lifestyle, we still know little about how major evolutionary processes, such as gene duplication (GD) and horizontal gene transfer (HGT), have interacted with clustered and non-clustered fungal metabolic pathways to give rise to this metabolic versatility. We examined the synteny and evolutionary history of 247,202 fungal genes encoding enzymes that catalyze 875 distinct metabolic reactions from 130 pathways in 208 diverse genomes. We found that gene clustering varied greatly with respect to metabolic category and lineage; for example, clustered genes in Saccharomycotina yeasts were overrepresented in nucleotide metabolism, whereas clustered genes in Pezizomycotina were more common in lipid and amino acid metabolism. The effects of both GD and HGT were more pronounced in clustered genes than in their non-clustered counterparts and were differentially distributed across fungal lineages; specifically, GD, which was an order of magnitude more abundant than HGT, was most frequently observed in Agaricomycetes, whereas HGT was much more prevalent in Pezizomycotina. The effect of HGT in some Pezizomycotina was particularly strong; for example, we identified 111 HGT events associated with the 15 Aspergillus genomes, which sharply contrasts with the 60 HGT events detected for the 48 genomes from the entire Saccharomycotina subphylum. Finally, the impact of GD within a metabolic category was typically consistent across all fungal lineages, whereas the impact of HGT was variable. These results indicate that GD is the dominant process underlying fungal metabolic diversity, whereas HGT is episodic and acts in a category- or lineage-specific manner. Both processes have a greater impact on clustered genes, suggesting that metabolic gene clusters represent hotspots for the generation of fungal metabolic diversity.

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JGI News: Retracing the Roots of Plant-Fungal Symbiosis (2015)

JGI News: Retracing the Roots of Plant-Fungal Symbiosis (2015) | Plants and Microbes | Scoop.it

Understanding how plants and fungi developed symbiotic relationships.


With apologies to the poet John Donne, and based on recent work from the U.S. Department of Energy Joint Genome Institute (DOE JGI), a DOE Office of Science user facility, it can be said that no plant is an island, entire of itself. Unseen by the human eye, plants interact with many species of fungi and other microbes in the surrounding environment, and these exchanges can impact the plant’s health and tolerance to stressors such as drought or disease, as well as the global carbon cycle.


To understand the basis for fungal symbiotic relationships with plants, a team of DOE JGI researchers led by Igor Grigoriev and longtime collaborators at the French National Institute for Agricultural Research (INRA) and Clark University conducted the first broad, comparative phylogenomic analysis of mycorrhizal fungi, drawing on 49 fungal genomes, 18 of which were sequenced for this study. The 18 new fungal sequences included 13 mycorrhizal genomes, from ectomycorrhizal fungi that penetrate the host roots, and including species that comingle with orchid and heathland (which include blueberry, heather, and heath) plant roots. Published ahead online February 23, 2015 in Nature Genetics, these researchers describe how the comparative analyses of these genomes allowed them to track the evolution of mycorrhizal fungi. The results help researchers understand how plants and fungi developed symbiotic relationships, and how the mutualistic association provides host plants with beneficial traits for environmental adaptation.

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