Ecology of host plant resistance
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Drought stress affects Solanum lycopersicum susceptibility to Bactericera cockerelli colonization - Huot - 2017 - Entomologia Experimentalis et Applicata - Wiley Online Library

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Recent outbreaks in plant diseases associated with Liberibacter pathogens have impacted large areas of western and southern North America. The increase in frequency and severity of drought could render plants more susceptible to the colonization by insect vectors. Experiments were conducted in a laboratory setting to evaluate the influence of water scarcity on drought stress of tomato plants, Solanum lycopersicum L. (Solanaceae). Weekly water treatment of 200, 100, and 50 ml resulted in unstressed (control, Ψw = −0.55 MPa), lowly drought‐stressed (LDS, Ψw = −0.70 MPa), and moderately drought‐stressed (MDS, Ψw = −0.87 MPa) plants, respectively. By controlling for both water availability and plant drought stress, the effect of drought stress on S. lycopersicum susceptibility to potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae), was evaluated. In a no‐choice experiment, MDS plants had significantly more B. cockerelli nymphs than control plants. However, plant susceptibility to B. cockerelli colonization was not due to the oviposition preference for MDS, but rather to the higher B. cockerelli nymphal survival on MDS than on control plants. Nymphal survival of B. cockerelli on MDS plants was consistently and significantly higher than on control plants. Throughout all nymphal stages, B. cockerelli had higher survival on MDS plants than on control plants. Drought stress not only enhanced B. cockerelli survival on S. lycopersicum but it also resulted in 60% more adults produced on water‐stressed plants than on control plants. Therefore, as adults can move from plant to plant, drought stress could increase B. cockerelli's dispersion potential. Although plant drought stress improved B. cockerelli survival, it did not affect B. cockerelli oviposition. No difference in number of offspring was found between B. cockerelli adults that developed on MDS vs. control plants. These results might be relevant to B. cockerelli outbreaks and Liberibacter epidemics.
 
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Trade-Offs in Arbuscular Mycorrhizal Symbiosis: Disease Resistance, Growth Responses and Perspectives for Crop Breeding

Trade-Offs in Arbuscular Mycorrhizal Symbiosis: Disease Resistance, Growth Responses and Perspectives for Crop Breeding | Ecology of host plant resistance | Scoop.it
There is an increasing need to develop high-yielding, disease-resistant crops and reduce fertilizer usage. Combining disease resistance with efficient nutrient assimilation through improved associations with symbiotic microorganisms would help to address this. Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with most terrestrial plants, resulting in nutritional benefits and the enhancement of stress tolerance and disease resistance. Despite these advantages, arbuscular mycorrhizal (AM) interactions are not normally directly considered in plant breeding. Much of our understanding of the mechanisms of AM symbiosis comes from model plants, which typically exhibit positive growth responses. However, applying this knowledge to crops has not been straightforward. In many crop plants, phosphate uptake and growth responses in AM-colonized plants are variable, with AM plants exhibiting sometimes zero or negative growth responses and lower levels of phosphate acquisition. Host plants must also balance the ability to host AMF with the ability to resist pathogens. Advances in understanding the plant immune system have revealed similarities between pathogen infection and AM colonization that may lead to trade-offs between symbiosis and disease resistance. This review considers the potential trade-offs between AM colonization, agronomic traits and disease resistance and highlights the need for translational research to apply fundamental knowledge to crop improvement.

Via Jonathan Plett, Francis Martin
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Analysis of Acquisition and Titer of Maize Mosaic Rhabdovirus in Its Vector, Peregrinus maidis (Hemiptera: Delphacidae)

Analysis of Acquisition and Titer of Maize Mosaic Rhabdovirus in Its Vector, Peregrinus maidis (Hemiptera: Delphacidae) | Ecology of host plant resistance | Scoop.it
Abstract

The corn planthopper, Peregrinus maidis (Ashmead) (Hemiptera: Delphacidae), transmits Maize mosaic rhabdovirus (MMV), an important pathogen of maize and sorghum, in a persistent propagative manner. To better understand the vectorial capacity of P. maidis, we determined the efficiency of MMV acquisition by nymphal and adult stages, and characterized MMV titer through development. Acquisition efficiency, i.e., proportion of insects that acquired the virus, was determined by reverse transcriptase polymerase chain reaction (RT-PCR) and virus titer of individual insects was estimated by quantitative RT-PCR. Acquisition efficiency of MMV differed significantly between nymphs and adults. MMV titer increased significantly over time and throughout insect development from nymphal to adult stage, indication of virus replication in the vector during development. There was a positive association between the vector developmental stage and virus titer. Also, the average titer in male insects was threefold higher than female titers, and this difference persisted up to 30 d post adult eclosion. Overall, our findings indicate that nymphs are more efficient than adults at acquiring MMV and virus accumulated in the vector over the course of nymphal development. Furthermore, sustained infection over the lifespan of P. maidis indicates a potentially high capacity of this vector to transmit MMV.


Via Rabenstein, Frank
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Symbionts protect aphids from parasitic wasps by attenuating herbivore-induced plant volatiles

Symbionts protect aphids from parasitic wasps by attenuating herbivore-induced plant volatiles | Ecology of host plant resistance | Scoop.it
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Via julien levy
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Chinese scientists may have just found a new way to feed 200 million people

Chinese scientists may have just found a new way to feed 200 million people | Ecology of host plant resistance | Scoop.it
Scientists in China have developed several types of rice that can be grown in seawater, potentially creating enough food for 200 million people. Researchers have been trying to grow the grain in salty water for decades but have only now developed varieties that could be commercially viable. The rice was grown in a field near the Yellow Sea coastal city of Qingdao in China’s eastern Shandong province. 200 different types of the grain were planted to investigate which would grow best in salty conditions. 
Via Neelima Sinha
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Chewing sandpaper: grit, plant apparency and plant defense in sand-entrapping plants - LoPresti - 2016 - Ecology - Wiley Online Library

Chewing sandpaper: grit, plant apparency and plant defense in sand-entrapping plants - LoPresti - 2016 - Ecology - Wiley Online Library | Ecology of host plant resistance | Scoop.it
Abstract Sand entrapment on plant surfaces, termed psammophory or sand armor, is a phylogenetically and geographically widespread trait.
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Plant mating system transitions drive the macroevolution of defense strategies

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Host Plant Induced Variation in Gut Bacteria of Helicoverpa armigera

Host Plant Induced Variation in Gut Bacteria of  Helicoverpa armigera | Ecology of host plant resistance | Scoop.it
Helicoverpa are important polyphagous agricultural insect pests and they have a worldwide distribution. In this study, we report the bacterial community structure in the midgut of fifth instar larvae of Helicoverpa armigera , a species prevalent in the India, China, South Asia, South East Asia, Southern & Eastern Africa and Australia. Using culturable techniques, we isolated and identified members of Bacillus firmus , Bacillus niabense , Paenibacillus jamilae , Cellulomonas variformis , Acinetobacter schindleri , Micrococcus yunnanesis , Enterobacter sp., and Enterococcus cassiliflavus in insect samples collected from host plants grown in different parts of India. Besides these the presence of Sphingomonas , Ralstonia , Delftia , Paracoccus and Bacteriodetes was determined by culture independent molecular analysis. We found that Enterobacter and Enterococcus were universally present in all our Helicoverpa samples collected from different crops and in different parts of India. The bacterial diversity varied greatly among insects that were from different host plants than those from the same host plant of different locations. This result suggested that the type of host plant greatly influences the midgut bacterial diversity of H. armigera , more than the location of the host plant. On further analyzing the leaf from which the larva was collected, it was found that the H. armigera midgut bacterial community was similar to that of the leaf phyllosphere. This finding indicates that the bacterial flora of the larval midgut is influenced by the leaf surface bacterial community of the crop on which it feeds. Additionally, we found that laboratory made media or the artificial diet is a poor bacterial source for these insects compared to a natural diet of crop plant.
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host plant defenses can affect microbial community in insect

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How to Win the War on Bugs? Listen to Plants. They’ve Been Fighting Longer Than We Have.

How to Win the War on Bugs? Listen to Plants. They’ve Been Fighting Longer Than We Have. | Ecology of host plant resistance | Scoop.it
We are losing the war on bugs. Every year, we dump 1 billion tons of insecticides on them; every year, they eat up to a fifth of the crops we grow. It’s a lose-lose scenario. Insecticides are expensive to make and use: Apple trees, for example, must be sprayed 20...

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The Destructive Citrus Pathogen, ‘Candidatus Liberibacter asiaticus’ Encodes a Functional Flagellin Characteristic of a Pathogen-Associated Molecular Pattern

The Destructive Citrus Pathogen, ‘Candidatus Liberibacter asiaticus’ Encodes a Functional Flagellin Characteristic of a Pathogen-Associated Molecular Pattern | Ecology of host plant resistance | Scoop.it
PLOS ONE: an inclusive, peer-reviewed, open-access resource from the PUBLIC LIBRARY OF SCIENCE. Reports of well-performed scientific studies from all disciplines freely available to the whole world.
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Induced Release of a Plant-Defense Volatile ‘Deceptively’ Attracts Insect Vectors to Plants Infected with a Bacterial Pathogen

Induced Release of a Plant-Defense Volatile ‘Deceptively’ Attracts Insect Vectors to Plants Infected with a Bacterial Pathogen | Ecology of host plant resistance | Scoop.it
From molecules to physiology
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Induced Plant Resistance to Herbivory

Induced Plant Resistance to Herbivory | Ecology of host plant resistance | Scoop.it
Flowering plants dominate much of the Earth's surface and yet, as sessile organisms, they must constantly resist attack by numerous voracious herbivores. Survival in the face of an abundance of insect predators relies on ...
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Frontiers | The Microbe-Free Plant: Fact or Artifact? | Plant-Microbe Interaction

Plant-microbe interactions are ubiquitous. Plants are often colonized by pathogens but even more commonly engaged in neutral or mutualistic interactions with microbes: below-ground microbial plant ...

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Global gene regulation in tomato plant ( Solanum lycopersicum) responding to vector ( Bactericera cockerelli) feeding and pathogen (‘ Candidatus Liberibacter solanacearum’) infection

Global gene regulation in tomato plant ( Solanum lycopersicum) responding to vector ( Bactericera cockerelli) feeding and pathogen (‘ Candidatus Liberibacter solanacearum’) infection | Ecology of host plant resistance | Scoop.it
Key message Different responses are elicited in tomato plants by Bactericera cockerelli harboring or not the pathogen ‘ Candidatus Liberibacter solanacearum’.
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‘Candidatus Liberibacter solanacearum’ (Lso) has emerged as a major pathogen of crops worldwide. This bacterial pathogen is transmitted by Bactericera cockerelli, the tomato psyllid, to solanaceous crops. In this study, the transcriptome profiles of tomato (Solanum lycopersicum) exposed to B. cockerelli infestation and Lso infection were evaluated at 1, 2 and 4 weeks following colonization and/or infection. The plant transcriptional responses to Lso-negative B. cockerelli were different than plant responses to Lso-positive B. cockerelli. The comparative transcriptome analyses of plant responses to Lso-negative B. cockerelli revealed the up-regulation of genes associated with plant defenses regardless of the time-point. In contrast, the general responses to Lso-positive B. cockerelli and Lso-infection were temporally different. Infected plants down-regulated defense genes at week one while delayed the up-regulation of the defense genes until weeks two and four, time points in which early signs of disease development were also detected in the transcriptional response. For example, infected plants regulated carbohydrate metabolism genes which could be linked to the disruption of sugar distribution usually associated with Lso infection. Also, infected plants down-regulated photosynthesis-related genes potentially resulting in plant chlorosis, another symptom associated with Lso infection. Overall, this study highlights that tomato plants induce different sets of genes in response to different stages of B. cockerelli infestation and Lso infection. This is the first transcriptome study of tomato responses to B. cockerelli and Lso, a first step in the direction of finding plant defense genes to enhance plant resistance.
 
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Resistance to citrus canker induced by a variant of Xanthomonas citri ssp. citri is associated with a hypersensitive cell death response involving autophagy‐associated vacuolar processes

Resistance to citrus canker induced by a variant of Xanthomonas citri ssp. citri is associated with a hypersensitive cell death response involving autophagy‐associated vacuolar processes | Ecology of host plant resistance | Scoop.it
Xanthomonas citri ssp. citri (X. citri) is the causal agent of Asiatic citrus canker, a disease that seriously affects most commercially important Citrus species worldwide. We have identified previously a natural variant, X. citri AT, that triggers a host-specific defence response in Citrus limon. However, the mechanisms involved in this canker disease resistance are unknown. In this work, the defence response induced by X. citri AT was assessed by transcriptomic, physiological and ultrastructural analyses, and the effects on bacterial biofilm formation were monitored in parallel. We show that X. citri AT triggers a hypersensitive response associated with the interference of biofilm development and arrest of bacterial growth in C. limon. This plant response involves an extensive transcriptional reprogramming, setting in motion cell wall reinforcement, the oxidative burst and the accumulation of salicylic acid (SA) and phenolic compounds. Ultrastructural analyses revealed subcellular changes involving the activation of autophagy-associated vacuolar processes. Our findings show the activation of SA-dependent defence in response to X. citri AT and suggest a coordinated regulation between the SA and flavonoid pathways, which is associated with autophagy mechanisms that control pathogen invasion in C. limon. Furthermore, this defence response protects C. limon plants from disease on subsequent challenges by pathogenic X. citri. This knowledge will allow the rational exploitation of the plant immune system as a biotechnological approach for the management of the disease.
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New Phytologist: Characterization of an antimicrobial and phytotoxic ribonuclease secreted by the fungal wheat pathogen Zymoseptoria tritici (2017)

New Phytologist: Characterization of an antimicrobial and phytotoxic ribonuclease secreted by the fungal wheat pathogen Zymoseptoria tritici (2017) | Ecology of host plant resistance | Scoop.it
 The fungus Zymoseptoria tritici is the causal agent of Septoria Tritici Blotch (STB) disease of wheat leaves. Zymoseptoria tritici secretes many functionally uncharacterized effector proteins during infection. Here, we characterized a secreted ribonuclease (Zt6) with an unusual biphasic expression pattern.Transient expression systems were used to characterize Zt6, and mutants thereof, in both host and non-host plants. Cell-free protein expression systems monitored the impact of Zt6 protein on functional ribosomes, and in vitroassays of cells treated with recombinant Zt6 determined toxicity against bacteria, yeasts and filamentous fungi.We demonstrated that Zt6 is a functional ribonuclease and that phytotoxicity is dependent on both the presence of a 22-amino-acid N-terminal ‘loop’ region and its catalytic activity. Zt6 selectively cleaves both plant and animal rRNA species, and is toxic to wheat, tobacco, bacterial and yeast cells, but not to Z. tritici itself.Zt6 is the first Z. tritici effector demonstrated to have a likely dual functionality. The expression pattern of Zt6 and potent toxicity towards microorganisms suggest that, although it may contribute to the execution of wheat cell death, it is also likely to have an important secondary function in antimicrobial competition and niche protection.
Via Kamoun Lab @ TSL
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AgTech Startups Offer Hope in Brutal Citrus Greening Fight

AgTech Startups Offer Hope in Brutal Citrus Greening Fight | Ecology of host plant resistance | Scoop.it
Citrus greening continues to ravage citrus groves worldwide with no cure even after $400 million in investment form the USDA.

Via julien levy
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Late blight threatens Michigan tomatoes

Late blight threatens Michigan tomatoes | Ecology of host plant resistance | Scoop.it
Michigan potatoes infected with late blight have been found. Tomato growers should also be on alert for this disease.

Michigan potatoes infected with late blight have been found. Tomato growers should also be on alert for this disease.

 
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Plant mating systems affect adaptive plasticity in response to herbivory - Campbell - 2014 - The Plant Journal - Wiley Online Library

Plant mating systems affect adaptive plasticity in response to herbivory - Campbell - 2014 - The Plant Journal - Wiley Online Library | Ecology of host plant resistance | Scoop.it
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Timeline Photos - Food and Agriculture Organization of the United Nations (FAO) | Facebook

Timeline Photos - Food and Agriculture Organization of the United Nations (FAO) | Facebook | Ecology of host plant resistance | Scoop.it
#Biodiversity for #food and #agriculture is among the earth’s most important resources. Crops, livestock, aquatic organisms, forest trees,...
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Diaphorina citri (Hemiptera: Liviidae) Abundance in Puerto Rico Declines with Elevation

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Scientists Find Mosquito Receptors that Make DEET Effective as Repellent

Scientists Find Mosquito Receptors that Make DEET Effective as Repellent | Ecology of host plant resistance | Scoop.it
Scientists have long known that DEET, the gold standard of insect repellents for more than six decades, effectively repels mosquitoes, but now researchers in the Walter Leal Lab at the University o...
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Plant defensive compound methyl jasmonate may play an important role in mosquito repellent.

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Induction of Salicylic Acid–Mediated Defense Response in Perennial Ryegrass Against Infection by Magnaporthe oryzae

Induction of Salicylic Acid–Mediated Defense Response in Perennial Ryegrass Against Infection by Magnaporthe oryzae | Ecology of host plant resistance | Scoop.it

Incorporation of plant defense activators is an innovative approach to development of an integrated strategy for the management of turfgrass diseases. The effects of salicylic acid (SA), benzothiadiazole (BTH, chemical analog of SA), jasmonic acid (JA), and ethephon (ET, an ethylene-releasing compound) on development of gray leaf spot in perennial ryegrass (Lolium perenne L.) caused by Magnaporthe oryzae were evaluated. Gray leaf spot disease incidence and severity were significantly decreased when plants were treated prior to inoculation with SA, BTH, and partially by ET but not by JA. Accumulation of endogenous SA and elevated expression of pathogenesis-related (PR)-1, PR-3.1, and PR-5 genes were associated with inoculation of plants by M. oryzae. Treatment of plants with SA enhanced expression levels of PR-3.1 and PR-5 but did not affect the PR-1 level, whereas BTH treatment enhanced relative expression levels of all three PR genes. Microscopic observations of leaves inoculated with M. oryzae revealed higher frequencies of callose deposition at the penetration sites in SA- and BTH-treated plants compared with the control plants (treated with water). These results suggest that early and higher induction of these genes by systemic resistance inducers may provide perennial ryegrass with a substantial advantage to defend against infection by M. oryzae.

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Plant Resistance against Herbivory

Plant Resistance against Herbivory | Ecology of host plant resistance | Scoop.it
Every bite an herbivore takes comes at the expense of a plant. Are plants passive victims or do they actively resist these attacks?
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The evolutionary strategies of plant defenses have a dynamic impact on the adaptations and interactions of vectors and pathogens - Huot - 2013 - Insect Science - Wiley Online Library

The evolutionary strategies of plant defenses have a dynamic impact on the adaptations and interactions of vectors and pathogens - Huot - 2013 - Insect Science - Wiley Online Library | Ecology of host plant resistance | Scoop.it
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