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current knowledge on the ralstonia solanacearum type iii secretion system. 201323617636
the xylem as battleground for plant hosts and vascular wilt pathogens.vascular wilts are among the most destructive plant diseases that occur in annual crops as well as in woody perennials. these diseases are generally caused by soil-borne bacteria, fungi, and oomycetes that infect through the roots and enter the water-conducting xylem vessels where they proliferate and obstruct the transportation of water and minerals. as a consequence, leaves wilt and die, which may lead to impairment of the whole plant and eventually to death of the plant. cultural, chemical, a ...201323630534
regulate and be regulated: integration of defense and other signals by the atmyb30 transcription factor.transcriptional regulation in host cells plays a crucial role in the establishment of plant defense and associated cell death in response to pathogen attack. here, we review our current knowledge of the transcriptional control of plant defenses with a focus on the myb family of transcription factors (tfs). within this family, the arabidopsis myb protein atmyb30 is a key regulator of plant defenses and one of the best characterized myb regulators directing defense-related transcriptional response ...201323596456
nuclear jasmonate and salicylate signaling and crosstalk in defense against pathogens.an extraordinary progress has been made over the last two decades on understanding the components and mechanisms governing plant innate immunity. after detection of a pathogen, effective plant resistance depends on the activation of a complex signaling network integrated by small signaling molecules and hormonal pathways, and the balance of these hormone systems determines resistance to particular pathogens. the discovery of new components of hormonal signaling pathways, including plant nuclear ...201323577014
plant nucleotide binding site-leucine-rich repeat (nbs-lrr) genes: active guardians in host defense responses.the most represented group of resistance genes are those of the nucleotide binding site-leucine-rich repeat (nbs-lrr) class. these genes are very numerous in the plant genome, and they often occur in clusters at specific loci following gene duplication and amplification events. to date, hundreds of resistance genes and relatively few quantitative trait loci for plant resistance to pathogens have been mapped in different species, with some also cloned. when these nbs-lrr genes have been physically ...201323549266
plant-bacterium interactions analyzed by proteomics.the evolution of the plant immune response has resulted in a highly effective defense system that is able to resist potential attack by microbial pathogens. the primary immune response is referred to as pathogen associated molecular pattern (pamp) triggered immunity and has evolved to recognize common features of microbial pathogens. in response to the delivery of pathogen effector proteins, plants acquired r proteins to fight against pathogen attack. r-dependent defense response is important in ...201323424014
phosphorylation of hopq1, a type iii effector from pseudomonas syringae, creates a binding site for host 14-3-3 proteins.hopq1 (for hrp outer protein q), a type iii effector secreted by pseudomonas syringae pv phaseolicola, is widely conserved among diverse genera of plant bacteria. it promotes the development of halo blight in common bean (phaseolus vulgaris). however, when this same effector is injected into nicotiana benthamiana cells, it is recognized by the immune system and prevents infection. although the ability to synthesize hopq1 determines host specificity, the role it plays inside plant cells remains u ...201323396834
comparative genomics of 12 strains of erwinia amylovora identifies a pan-genome with a large conserved core.the plant pathogen erwinia amylovora can be divided into two host-specific groupings; strains infecting a broad range of hosts within the rosaceae subfamily spiraeoideae (e.g., malus, pyrus, crataegus, sorbus) and strains infecting rubus (raspberries and blackberries). comparative genomic analysis of 12 strains representing distinct populations (e.g., geographic, temporal, host origin) of e. amylovora was used to describe the pan-genome of this major pathogen. the pan-genome contains 5751 coding ...201323409014
characterization and dna-binding specificities of ralstonia tal-like effectors.transcription activator-like effectors (tales) from xanthomonas sp. have been used as customizable dna-binding modules for genome-engineering applications. ralstonia solanacearum tale-like proteins (rtls) exhibit similar structural features to tales, including a central dna-binding domain composed of 35 amino acid-long repeats. here, we characterize the rtls and show that they localize in the plant cell nucleus, mediate dna binding, and might function as transcriptional activators. rtls have a u ...201323300258
overexpression of a novel biotrophy-specific colletotrichum truncatum effector, ctnudix, in hemibiotrophic fungal phytopathogens causes incompatibility with their host plants.the hemibiotrophic fungus colletotrichum truncatum causes anthracnose disease on lentils and a few other grain legumes. it shows initial symptomless intracellular growth, where colonized host cells remain viable (biotrophy), and then switches to necrotrophic growth, killing the colonized host plant tissues. here, we report a novel effector gene, ctnudix, from c. truncatum that is exclusively expressed during the late biotrophic phase (before the switch to necrotrophy) and elicits a hypersensitiv ...201322962277
agrobacterium infection and plant defense-transformation success hangs by a thread.the value of agrobacterium tumefaciens for plant molecular biologists cannot be appreciated enough. this soil-borne pathogen has the unique capability to transfer dna (t-dna) into plant systems. gene transfer involves both bacterial and host factors, and it is the orchestration of these factors that determines the success of transformation. some plant species readily accept integration of foreign dna, while others are recalcitrant. the timing and intensity of the microbially activated host defen ...201324391655
prophage-mediated dynamics of 'candidatus liberibacter asiaticus' populations, the destructive bacterial pathogens of citrus huanglongbing.prophages are highly dynamic components in the bacterial genome and play an important role in intraspecies variations. there are at least two prophages in the chromosomes of candidatus liberibacter asiaticus' (las) floridian isolates. las is both unculturable and the most prevalent species of liberibacter pathogens that cause huanglongbing (hlb), a worldwide destructive disease of citrus. in this study, seven new prophage variants resulting from two hyper-variable regions were identified by scre ...201324349235
a high-throughput virus-induced gene silencing protocol identifies genes involved in multi-stress tolerance.understanding the function of a particular gene under various stresses is important for engineering plants for broad-spectrum stress tolerance. although virus-induced gene silencing (vigs) has been used to characterize genes involved in abiotic stress tolerance, currently available gene silencing and stress imposition methodology at the whole plant level is not suitable for high-throughput functional analyses of genes. this demands a robust and reliable methodology for characterizing genes invol ...201324289810
genomic survey of pathogenicity determinants and vntr markers in the cassava bacterial pathogen xanthomonas axonopodis pv. manihotis strain cio151.xanthomonas axonopodis pv. manihotis (xam) is the causal agent of bacterial blight of cassava, which is among the main components of human diet in africa and south america. current information about the molecular pathogenicity factors involved in the infection process of this organism is limited. previous studies in other bacteria in this genus suggest that advanced draft genome sequences are valuable resources for molecular studies on their interaction with plants and could provide valuable too ...201324278159
a comparative hidden markov model analysis pipeline identifies proteins characteristic of cereal-infecting fungi.fungal pathogens cause devastating losses in economically important cereal crops by utilising pathogen proteins to infect host plants. secreted pathogen proteins are referred to as effectors and have thus far been identified by selecting small, cysteine-rich peptides from the secretome despite increasing evidence that not all effectors share these attributes.201324252298
tomato fruit and seed colonization by clavibacter michiganensis subsp. michiganensis through external and internal routes.the gram-positive bacterium clavibacter michiganensis subsp. michiganensis, causal agent of bacterial wilt and canker of tomato, is an economically devastating pathogen that inflicts considerable damage throughout all major tomato-producing regions. annual outbreaks continue to occur in new york, where c. michiganensis subsp. michiganensis spreads via infected transplants, trellising stakes, tools, and/or soil. globally, new outbreaks can be accompanied by the introduction of contaminated seed s ...201324014525
antimicrobial nodule-specific cysteine-rich peptides induce membrane depolarization-associated changes in the transcriptome of sinorhizobium meliloti.leguminous plants establish symbiosis with nitrogen-fixing alpha- and betaproteobacteria, collectively called rhizobia, which provide combined nitrogen to support plant growth. members of the inverted repeat-lacking clade of legumes impose terminal differentiation on their endosymbiotic bacterium partners with the help of the nodule-specific cysteine-rich (ncr) peptide family composed of close to 600 members. among the few tested ncr peptides, cationic ones had antirhizobial activity measured by ...201323995935
bacterial effector activates jasmonate signaling by directly targeting jaz transcriptional repressors.gram-negative bacterial pathogens deliver a variety of virulence proteins through the type iii secretion system (t3ss) directly into the host cytoplasm. these type iii secreted effectors (t3ses) play an essential role in bacterial infection, mainly by targeting host immunity. however, the molecular basis of their functionalities remains largely enigmatic. here, we show that the pseudomonas syringae t3se hopz1a, a member of the widely distributed yopj effector family, directly interacts with jasm ...201324204266
the current status of the elemental defense hypothesis in relation to pathogens.metal hyperaccumulating plants are able to accumulate exceptionally high concentrations of metals, such as zinc, nickel, or cadmium, in their aerial tissues. these metals reach concentrations that would be toxic to most other plant species. this trait has evolved multiple times independently in the plant kingdom. recent studies have provided new insight into the ecological and evolutionary significance of this trait, by showing that some metal hyperaccumulating plants can use high concentrations ...201324137169
small rna sx13: a multifaceted regulator of virulence in the plant pathogen xanthomonas.small noncoding rnas (srnas) are ubiquitous posttranscriptional regulators of gene expression. using the model plant-pathogenic bacterium xanthomonas campestris pv. vesicatoria (xcv), we investigated the highly expressed and conserved srna sx13 in detail. deletion of sx13 impinged on xcv virulence and the expression of genes encoding components and substrates of the hrp type iii secretion (t3s) system. qrt-pcr analyses revealed that sx13 promotes mrna accumulation of hrpx, a key regulator of the ...201324068933
vigs-mediated forward genetics screening for identification of genes involved in nonhost resistance.nonhost disease resistance of plants against bacterial pathogens is controlled by complex defense pathways. understanding this mechanism is important for developing durable disease-resistant plants against wide range of pathogens. virus-induced gene silencing (vigs)-based forward genetics screening is a useful approach for identification of plant defense genes imparting nonhost resistance. tobacco rattle virus (trv)-based vigs vector is the most efficient vigs vector to date and has been efficie ...201323995956
loss of function in mlo orthologs reduces susceptibility of pepper and tomato to powdery mildew disease caused by leveillula taurica.powdery mildew disease caused by leveillula taurica is a serious fungal threat to greenhouse tomato and pepper production. in contrast to most powdery mildew species which are epiphytic, l. taurica is an endophytic fungus colonizing the mesophyll tissues of the leaf. in barley, arabidopsis, tomato and pea, the correct functioning of specific homologues of the plant mlo gene family has been found to be required for pathogenesis of epiphytic powdery mildew fungi. the aim of this study was to inves ...201323923019
overexpression of atshn1/win1 provokes unique defense responses.the plant cell cuticle serves as the first barrier protecting plants from mechanical injury and invading pathogens. the cuticle can be breached by cutinase-producing pathogens and the degradation products may activate pathogenesis signals in the invading pathogens. cuticle degradation products may also trigger the plant's defense responses. botrytis cinerea is an important plant pathogen, capable of attacking and causing disease in a wide range of plant species. arabidopsis thaliana shn1-1d is a ...201323922943
the salmonella type iii effector ssph2 specifically exploits the nlr co-chaperone activity of sgt1 to subvert immunity.to further its pathogenesis, s. typhimurium delivers effector proteins into host cells, including the novel e3 ubiquitin ligase (nel) effector ssph2. using model systems in a cross-kingdom approach we gained further insight into the molecular function of this effector. here, we show that ssph2 modulates innate immunity in both mammalian and plant cells. in mammalian cell culture, ssph2 significantly enhanced nod1-mediated il-8 secretion when transiently expressed or bacterially delivered. in add ...201323935490
receptor-like cytoplasmic kinases are pivotal components in pattern recognition receptor-mediated signaling in plant immunity.innate immunity is generally initiated with recognition of conserved pathogen-associated molecular patterns (pamps). pamps are perceived by pattern recognition receptors (prrs), leading to activation of a series of immune responses, including the expression of defense genes, ros production and activation of map kinase. recent progress has indicated that receptor-like cytoplasmic kinases (rlcks) are directly activated by ligand-activated prrs and initiate pattern-triggered immunity (pti) in both ...201323857358
modulation of phytoalexin biosynthesis in engineered plants for disease resistance.phytoalexins are antimicrobial substances of low molecular weight produced by plants in response to infection or stress, which form part of their active defense mechanisms. starting in the 1950's, research on phytoalexins has begun with biochemistry and bio-organic chemistry, resulting in the determination of their structure, their biological activity as well as mechanisms of their synthesis and their catabolism by microorganisms. elucidation of the biosynthesis of numerous phytoalexins has perm ...201323880860
the receptor-like protein remax of arabidopsis detects the microbe-associated molecular pattern emax from xanthomonas.as part of their immune system, plants have pattern recognition receptors (prrs) that can detect a broad range of microbe-associated molecular patterns (mamps). here, we identified a prr of arabidopsis thaliana with specificity for the bacterial mamp emax from xanthomonads. response to emax seems to be restricted to the brassicaceae family and also varied among different accessions of arabidopsis. in crosses between sensitive accessions and the insensitive accession shakhdara, emax perception ma ...201323898033
pepper arginine decarboxylase is required for polyamine and γ-aminobutyric acid signaling in cell death and defense response.the xanthomonas campestris pv vesicatoria (xcv) effector avrbst induces a hypersensitive cell death in pepper (capsicum annuum). however, the molecular mechanisms underlying avrbst-triggered cell death are not fully understood. here, we identified pepper arginine decarboxylase (caadc1) as an avrbst-interacting protein, which is early and strongly induced in incompatible pepper-xcv interactions. bimolecular fluorescence complementation and coimmunoprecipitation assays showed that the caadc1-avrbs ...201323784462
oxylipin biosynthesis genes positively regulate programmed cell death during compatible infections with the synergistic pair potato virus x-potato virus y and tomato spotted wilt virus.one of the most severe symptoms caused by compatible plant-virus interactions is systemic necrosis, which shares common attributes with the hypersensitive response to incompatible pathogens. although several studies have identified viral symptom determinants responsible for systemic necrosis, mechanistic models of how they contribute to necrosis in infected plants remain scarce. here, we examined the involvement of different branches of the oxylipin biosynthesis pathway in the systemic necrosis ...201323487466
the pseudomonas syringae type iii effector avrrpt2 promotes pathogen virulence via stimulating arabidopsis auxin/indole acetic acid protein turnover.to accomplish successful infection, pathogens deploy complex strategies to interfere with host defense systems and subvert host physiology to favor pathogen survival and multiplication. modulation of plant auxin physiology and signaling is emerging as a common virulence strategy for phytobacteria to cause diseases. however, the underlying mechanisms remain largely elusive. we have previously shown that the pseudomonas syringae type iii effector avrrpt2 alters arabidopsis (arabidopsis thaliana) a ...201323632856
suppression of plant defense responses by extracellular metabolites from pseudomonas syringae pv. tabaci in nicotiana benthamiana.pseudomonas syringae pv. tabaci (pstab) is the causal agent of wildfire disease in tobacco plants. several pathovars of pseudomonas syringae produce a phytotoxic extracellular metabolite called coronatine (cor). cor has been shown to suppress plant defense responses. interestingly, pstab does not produce cor but still actively suppresses early plant defense responses. it is not clear if pstab produces any extracellular metabolites that actively suppress early defense during bacterial pathogenesi ...201323597256
modifying lignin to improve bioenergy feedstocks: strengthening the barrier against pathogens?lignin is a ubiquitous polymer present in cell walls of all vascular plants, where it rigidifies and strengthens the cell wall structure through covalent cross-linkages to cell wall polysaccharides. the presence of lignin makes the cell wall recalcitrant to conversion into fermentable sugars for bioenergy uses. therefore, reducing lignin content and modifying its linkages have become major targets for bioenergy feedstock development through either biotechnology or traditional plant breeding. in ...201323577013
diatom assemblages promote ice formation in large lakes.we present evidence for the directed formation of ice by planktonic communities dominated by filamentous diatoms sampled from the ice-covered laurentian great lakes. we hypothesize that ice formation promotes attachment of these non-motile phytoplankton to overlying ice, thereby maintaining a favorable position for the diatoms in the photic zone. however, it is unclear whether the diatoms themselves are responsible for ice nucleation. scanning electron microscopy revealed associations of bacteri ...201323552624
escherichia coli o157:h7 induces stronger plant immunity than salmonella enterica typhimurium sl1344.consumption of fresh produce contaminated with bacterial human pathogens has resulted in various, sometimes deadly, disease outbreaks. in this study, we assessed plant defense responses induced by the fully pathogenic bacteria escherichia coli o157:h7 and salmonella enterica serovar typhimurium sl1344 in both arabidopsis thaliana and lettuce (lactuca sativa). unlike sl1344, o157:h7 induced strong plant immunity at both pre-invasion and post-invasion steps of infection. for instance, o157:h7 trig ...201323301812
recognition of bacterial plant pathogens: local, systemic and transgenerational immunity.bacterial pathogens can cause multiple plant diseases and plants rely on their innate immune system to recognize and actively respond to these microbes. the plant innate immune system comprises extracellular pattern recognition receptors that recognize conserved microbial patterns and intracellular nucleotide binding leucine-rich repeat (nlr) proteins that recognize specific bacterial effectors delivered into host cells. plants lack the adaptive immune branch present in animals, but still afford ...201323909802
an abscisic acid-independent oxylipin pathway controls stomatal closure and immune defense in arabidopsis.plant stomata function in innate immunity against bacterial invasion and abscisic acid (aba) has been suggested to regulate this process. using genetic, biochemical, and pharmacological approaches, we demonstrate that (i) the arabidopsis thaliana nine-specific-lipoxygenase encoding gene, lox1, which is expressed in guard cells, is required to trigger stomatal closure in response to both bacteria and the pathogen-associated molecular pattern flagellin peptide flg22; (ii) lox1 participates in stom ...201323526882
phytopathogen type iii effectors as probes of biological systems.bacterial phytopathogens utilize a myriad of virulence factors to modulate their plant hosts in order to promote successful pathogenesis. one potent virulence strategy is to inject these virulence proteins into plant cells via the type iii secretion system. characterizing the host targets and the molecular mechanisms of type iii secreted proteins, known as effectors, has illuminated our understanding of eukaryotic cell biology. as a result, these effectors can serve as molecular probes to aid in ...201323433088
the pseudomonas syringae effector hopq1 promotes bacterial virulence and interacts with tomato 14-3-3 proteins in a phosphorylation-dependent manner.a key virulence strategy of bacterial pathogens is the delivery of multiple pathogen effector proteins into host cells during infection. the hrp outer protein q (hopq1) effector from pseudomonas syringae pv tomato (pto) strain dc3000 is conserved across multiple bacterial plant pathogens. here, we investigated the virulence function and host targets of hopq1 in tomato (solanum lycopersicum). transgenic tomato lines expressing dexamethasone-inducible hopq1 exhibited enhanced disease susceptibilit ...201323417089
the cytoskeleton is disrupted by the bacterial effector hrpz, but not by the bacterial pamp flg22, in tobacco by-2 cells.plant innate immunity is composed of two layers. basal immunity is triggered by pathogen-associated molecular patterns (pamps) such as the flagellin-peptide flg22 and is termed pamp-triggered immunity (pti). in addition, effector-triggered immunity (eti) linked with programmed cell death and cytoskeletal reorganization can be induced by pathogen-derived factors, such as the harpin proteins originating from phytopathogenic bacteria. to get insight into the link between cytoskeleton and pti or eti ...201323408828
activation of defense mechanisms against pathogens in mosses and flowering plants.during evolution, plants have developed mechanisms to cope with and adapt to different types of stress, including microbial infection. once the stress is sensed, signaling pathways are activated, leading to the induced expression of genes with different roles in defense. mosses (bryophytes) are non-vascular plants that diverged from flowering plants more than 450 million years ago, allowing comparative studies of the evolution of defense-related genes and defensive metabolites produced after mic ...201323380962
multiple phytohormone signalling pathways modulate susceptibility of tomato plants to alternaria alternata f. sp. lycopersici.three phytohormone molecules - ethylene (et), jasmonic acid (ja) and salicylic acid (sa) - play key roles in mediating disease response to necrotrophic fungal pathogens. this study investigated the roles of the et, ja, and sa pathways as well as their crosstalk during the interaction between tomato (solanum lycopersicum) plants and a necrotrophic fungal pathogen alternaria alternata f. sp. lycopersici (aal). both the et and jasmonic acid insensitive1 (jai1) receptor-dependent ja signalling pathw ...201323264518
a pathogen type iii effector with a novel e3 ubiquitin ligase architecture.type iii effectors are virulence factors of gram-negative bacterial pathogens delivered directly into host cells by the type iii secretion nanomachine where they manipulate host cell processes such as the innate immunity and gene expression. here, we show that the novel type iii effector xopl from the model plant pathogen xanthomonas campestris pv. vesicatoria exhibits e3 ubiquitin ligase activity in vitro and in planta, induces plant cell death and subverts plant immunity. e3 ligase activity is ...201323359647
interactions of salmonella with animals and plants.salmonella enterica species are gram-negative bacteria, which are responsible for a wide range of food- and water-borne diseases in both humans and animals, thereby posing a major threat to public health. recently, there has been an increasing number of reports, linking salmonella contaminated raw vegetables and fruits with food poisoning. many studies have shown that an essential feature of the pathogenicity of salmonella is its capacity to cross a number of barriers requiring invasion of a lar ...201425653644
interactions of salmonella with animals and plants.salmonella enterica species are gram-negative bacteria, which are responsible for a wide range of food- and water-borne diseases in both humans and animals, thereby posing a major threat to public health. recently, there has been an increasing number of reports, linking salmonella contaminated raw vegetables and fruits with food poisoning. many studies have shown that an essential feature of the pathogenicity of salmonella is its capacity to cross a number of barriers requiring invasion of a lar ...201425653644
image-based phenotyping of plant disease symptoms.plant diseases cause significant reductions in agricultural productivity worldwide. disease symptoms have deleterious effects on the growth and development of crop plants, limiting yields and making agricultural products unfit for consumption. for many plant-pathogen systems, we lack knowledge of the physiological mechanisms that link pathogen infection and the production of disease symptoms in the host. a variety of quantitative high-throughput image-based methods for phenotyping plant growth a ...201425601871
image-based phenotyping of plant disease symptoms.plant diseases cause significant reductions in agricultural productivity worldwide. disease symptoms have deleterious effects on the growth and development of crop plants, limiting yields and making agricultural products unfit for consumption. for many plant-pathogen systems, we lack knowledge of the physiological mechanisms that link pathogen infection and the production of disease symptoms in the host. a variety of quantitative high-throughput image-based methods for phenotyping plant growth a ...201425601871
microbe-associated molecular pattern-induced calcium signaling requires the receptor-like cytoplasmic kinases, pbl1 and bik1.plant perception of conserved microbe-derived or damage-derived molecules (so-called microbe- or damage-associated molecular patterns, mamps or damps, respectively) triggers cellular signaling cascades to initiate counteracting defence responses. using mamp-induced rise in cellular calcium levels as one of the earliest biochemical readouts, we initiated a genetic screen for components involved in early mamp signaling in arabidopsis thaliana.201425522736
interactions of xanthomonas type-iii effector proteins with the plant ubiquitin and ubiquitin-like pathways.in eukaryotes, regulated protein turnover is required during many cellular processes, including defense against pathogens. ubiquitination and degradation of ubiquitinated proteins via the ubiquitin-proteasome system (ups) is the main pathway for the turnover of intracellular proteins in eukaryotes. the extensive utilization of the ups in host cells makes it an ideal pivot for the manipulation of cellular processes by pathogens. like many other gram-negative bacteria, xanthomonas species secrete ...201425566304
in vitro activity of glucosinolates and their degradation products against brassica-pathogenic bacteria and fungi.glucosinolates (gsls) are secondary metabolites found in brassica vegetables that confer on them resistance against pests and diseases. both gsls and glucosinolate hydrolysis products (ghps) have shown positive effects in reducing soil pathogens. information about their in vitro biocide effects is scarce, but previous studies have shown sinigrin gsls and their associated allyl isothiocyanate (aitc) to be soil biocides. the objective of this work was to evaluate the biocide effects of 17 gsls and ...201425362058
in vitro activity of glucosinolates and their degradation products against brassica-pathogenic bacteria and fungi.glucosinolates (gsls) are secondary metabolites found in brassica vegetables that confer on them resistance against pests and diseases. both gsls and glucosinolate hydrolysis products (ghps) have shown positive effects in reducing soil pathogens. information about their in vitro biocide effects is scarce, but previous studies have shown sinigrin gsls and their associated allyl isothiocyanate (aitc) to be soil biocides. the objective of this work was to evaluate the biocide effects of 17 gsls and ...201425362058
genetic diversity analysis in a set of caricaceae accessions using resistance gene analogues.in order to assess genetic diversity of a set of 41 caricaceae accessions, this study used 34 primer pairs designed from the conserved domains of bacterial leaf blight resistance genes from rice, in a pcr based approach, to identify and analyse resistance gene analogues from various accessions of carica papaya, vasconcellea goudotiana, v. microcarpa, v. parviflora, v. pubescens, v. stipulata and, v. quercifolia and jacaratia spinosa.201425491793
pepper heat shock protein 70a interacts with the type iii effector avrbst and triggers plant cell death and immunity.heat shock proteins (hsps) function as molecular chaperones and are essential for the maintenance and/or restoration of protein homeostasis. the genus xanthomonas type iii effector protein avrbst induces hypersensitive cell death in pepper (capsicum annuum). here, we report the identification of the pepper cahsp70a as an avrbst-interacting protein. bimolecular fluorescence complementation and coimmunoprecipitation assays confirm the specific interaction between cahsp70a and avrbst in planta. the ...201425491184
pepper heat shock protein 70a interacts with the type iii effector avrbst and triggers plant cell death and immunity.heat shock proteins (hsps) function as molecular chaperones and are essential for the maintenance and/or restoration of protein homeostasis. the genus xanthomonas type iii effector protein avrbst induces hypersensitive cell death in pepper (capsicum annuum). here, we report the identification of the pepper cahsp70a as an avrbst-interacting protein. bimolecular fluorescence complementation and coimmunoprecipitation assays confirm the specific interaction between cahsp70a and avrbst in planta. the ...201425491184
improving crop disease resistance: lessons from research on arabidopsis and tomato.one of the great challenges for food security in the 21st century is to improve yield stability through the development of disease-resistant crops. crop research is often hindered by the lack of molecular tools, growth logistics, generation time and detailed genetic annotations, hence the power of model plant species. our knowledge of plant immunity today has been largely shaped by the use of models, specifically through the use of mutants. we examine the importance of arabidopsis and tomato as ...201425520730
peptidoglycan from fermentation by-product triggers defense responses in grapevine.plants are constantly under attack from a variety of microorganisms, and rely on a series of complex detection and response systems to protect themselves from infection. here, we found that a by-product of glutamate fermentation triggered defense responses in grapevine, increasing the expression of defense response genes in cultured cells, foliar chitinase activity, and resistance to infection by downy mildew in leaf explants. to identify the molecule that triggered this innate immunity, we frac ...201425427192
probing formation of cargo/importin-α transport complexes in plant cells using a pathogen effector.importin-αs are essential adapter proteins that recruit cytoplasmic proteins destined for active nuclear import to the nuclear transport machinery. cargo proteins interact with the importin-α armadillo repeat domain via nuclear localization sequences (nlss), short amino acids motifs enriched in lys and arg residues. plant genomes typically encode several importin-α paralogs that can have both specific and partially redundant functions. although some cargos are preferentially imported by a distin ...201425284001
probing formation of cargo/importin-α transport complexes in plant cells using a pathogen effector.importin-αs are essential adapter proteins that recruit cytoplasmic proteins destined for active nuclear import to the nuclear transport machinery. cargo proteins interact with the importin-α armadillo repeat domain via nuclear localization sequences (nlss), short amino acids motifs enriched in lys and arg residues. plant genomes typically encode several importin-α paralogs that can have both specific and partially redundant functions. although some cargos are preferentially imported by a distin ...201425284001
redundancy among phospholipase d isoforms in resistance triggered by recognition of the pseudomonas syringae effector avrrpm1 in arabidopsis thaliana.plants possess a highly sophisticated system for defense against microorganisms. so called mamp (microbe-associated molecular patterns) triggered immunity (mti) prevents the majority of non-adapted pathogens from causing disease. adapted plant pathogens use secreted effector proteins to interfere with such signaling. recognition of microbial effectors or their activity by plant resistance (r)-proteins triggers a second line of defense resulting in effector triggered immunity (eti). the latter us ...201425431578
a conserved peptide pattern from a widespread microbial virulence factor triggers pattern-induced immunity in arabidopsis.microbe- or host damage-derived patterns mediate activation of pattern-triggered immunity (pti) in plants. microbial virulence factor (effector)-triggered immunity (eti) constitutes a second layer of plant protection against microbial attack. various necrosis and ethylene-inducing peptide 1 (nep1)-like proteins (nlps) produced by bacterial, oomycete and fungal microbes are phytotoxic virulence factors that exert immunogenic activities through phytotoxin-induced host cell damage. we here show tha ...201425375108
structure of a diguanylate cyclase from thermotoga maritima: insights into activation, feedback inhibition and thermostability.large-scale production of bis-3'-5'-cyclic-di-gmp (c-di-gmp) would facilitate biological studies of numerous bacterial signaling pathways and phenotypes controlled by this second messenger molecule, such as virulence and biofilm formation. c-di-gmp constitutes also a potentially interesting molecule as a vaccine adjuvant. even though chemical synthesis of c-di-gmp can be done, the yields are incompatible with mass-production. tdgc, a stand-alone diguanylate cyclase (dgc or ggdef domain) from the ...201425360685
novel cyclic di-gmp effectors of the yajq protein family control bacterial virulence.bis-(3',5') cyclic di-guanylate (cyclic di-gmp) is a key bacterial second messenger that is implicated in the regulation of many critical processes that include motility, biofilm formation and virulence. cyclic di-gmp influences diverse functions through interaction with a range of effectors. our knowledge of these effectors and their different regulatory actions is far from complete, however. here we have used an affinity pull-down assay using cyclic di-gmp-coupled magnetic beads to identify cy ...201425329577
expression profiling during arabidopsis/downy mildew interaction reveals a highly-expressed effector that attenuates responses to salicylic acid.plants have evolved strong innate immunity mechanisms, but successful pathogens evade or suppress plant immunity via effectors delivered into the plant cell. hyaloperonospora arabidopsidis (hpa) causes downy mildew on arabidopsis thaliana, and a genome sequence is available for isolate emoy2. here, we exploit the availability of genome sequences for hpa and arabidopsis to measure gene-expression changes in both hpa and arabidopsis simultaneously during infection. using a high-throughput cdna tag ...201425329884
genomic insights into the evolutionary origin of xanthomonas axonopodis pv. citri and its ecological relatives.xanthomonas axonopodis pv. citri (xac) is the causal agent of citrus bacterial canker (cbc) and is a serious problem worldwide. like cbc, several important diseases in other fruits, such as mango, pomegranate, and grape, are also caused by xanthomonas pathovars that display remarkable specificity toward their hosts. while citrus and mango diseases were documented more than 100 years ago, the pomegranate and grape diseases have been known only since the 1950s and 1970s, respectively. interestingl ...201425085494
teaching fido new modification tricks. 201425255332
proteomics of effector-triggered immunity (eti) in plants.effector-triggered immunity (eti) was originally termed gene-for-gene resistance and dates back to fundamental observations of flax resistance to rust fungi by harold henry flor in the 1940s. since then, genetic and biochemical approaches have defined our current understanding of how plant "resistance" proteins recognize microbial effectors. more recently, proteomic approaches have expanded our view of the protein landscape during eti and contributed significant advances to our mechanistic under ...201425513776
pepper mitochondrial formate dehydrogenase1 regulates cell death and defense responses against bacterial pathogens.formate dehydrogenase (fdh; ec 1.2.1.2) is an nad-dependent enzyme that catalyzes the oxidation of formate to carbon dioxide. here, we report the identification and characterization of pepper (capsicum annuum) mitochondrial fdh1 as a positive regulator of cell death and defense responses. transient expression of fdh1 caused hypersensitive response (hr)-like cell death in pepper and nicotiana benthamiana leaves. the d-isomer -: specific 2-hydroxyacid dehydrogenase signatures of fdh1 were required ...201425237129
identification of novel coxiella burnetii icm/dot effectors and genetic analysis of their involvement in modulating a mitogen-activated protein kinase pathway.coxiella burnetii, the causative agent of q fever, is a human intracellular pathogen that utilizes the icm/dot type ivb secretion system to translocate effector proteins into host cells. to identify novel c. burnetii effectors, we applied a machine-learning approach to predict c. burnetii effectors, and examination of 20 such proteins resulted in the identification of 13 novel effectors. to determine whether these effectors, as well as several previously identified effectors, modulate conserved ...201424958706
altered cultivar resistance of kimchi cabbage seedlings mediated by salicylic acid, jasmonic acid and ethylene.two cultivars buram-3-ho (susceptible) and cr-hagwang (moderate resistant) of kimchi cabbage seedlings showed differential defense responses to anthracnose (colletotrichum higginsianum), black spot (alternaria brassicicola) and black rot (xanthomonas campestris pv. campestris, xcc) diseases in our previous study. defense-related hormones salicylic acid (sa), jasmonic acid (ja) and ethylene led to different transcriptional regulation of pathogenesis-related (pr) gene expression in both cultivars. ...201425289020
global analysis of the hrpl regulon in the plant pathogen pseudomonas syringae pv. tomato dc3000 reveals new regulon members with diverse functions.the type iii secretion system (t3ss) is required for virulence in the gram-negative plant pathogen pseudomonas syringae pv. tomato dc3000. the alternative sigma factor hrpl directly regulates expression of t3ss genes via a promoter sequence, often designated as the "hrp promoter." although the hrpl regulon has been extensively investigated in dc3000, it is not known whether additional regulon members remain to be found. to systematically search for hrpl-regulated genes, we used chromatin immunop ...201425170934
the phytotoxin coronatine is a multifunctional component of the virulence armament of pseudomonas syringae.plant pathogens deploy an array of virulence factors to suppress host defense and promote pathogenicity. numerous strains of pseudomonas syringae produce the phytotoxin coronatine (cor). a major aspect of cor function is its ability to mimic a bioactive jasmonic acid (ja) conjugate and thus target the ja-receptor cor-insensitive 1 (coi1). biological activities of cor include stimulation of ja-signaling and consequent suppression of sa-dependent defense through antagonistic crosstalk, antagonism ...201425156488
hell's bels: bacterial e3 ligases that exploit the eukaryotic ubiquitin machinery. 201425121772
apoplastic peroxidases are required for salicylic acid-mediated defense against pseudomonas syringae.reactive oxygen species (ros) generated by nadph oxidases or apoplastic peroxidases play an important role in the plant defense response. diminished expression of at least two arabidopsis thaliana peroxidase encoding genes, prx33 (at3g49110) and prx34 (at3g49120), as a consequence of anti-sense expression of a heterologous french bean peroxidase gene (asfbp1.1), were previously shown to result in reduced levels of ros following pathogen attack, enhanced susceptibility to a variety of bacterial a ...201425096754
apoplastic peroxidases are required for salicylic acid-mediated defense against pseudomonas syringae.reactive oxygen species (ros) generated by nadph oxidases or apoplastic peroxidases play an important role in the plant defense response. diminished expression of at least two arabidopsis thaliana peroxidase encoding genes, prx33 (at3g49110) and prx34 (at3g49120), as a consequence of anti-sense expression of a heterologous french bean peroxidase gene (asfbp1.1), were previously shown to result in reduced levels of ros following pathogen attack, enhanced susceptibility to a variety of bacterial a ...201425096754
analysis of clonostachys rosea-induced resistance to tomato gray mold disease in tomato leaves.tomato gray mold disease, caused by botrytis cinerea, is a serious disease in tomato. clonostachys rosea is an antagonistic microorganism to b. cinerea. to investigate the induced resistance mechanism of c. rosea, we examined the effects of these microorganisms on tomato leaves, along with changes in the activities of three defense enzymes (pal, ppo, gst), second messengers (no, h2o2, o2(-)) and phytohormones (iaa, aba, ga3, zt, meja, sa and c2h4). compared to the control, all treatments induced ...201425061981
lamp assay and rapid sample preparation method for on-site detection of flavescence dorée phytoplasma in grapevine.in europe the most devastating phytoplasma associated with grapevine yellows (gy) diseases is a quarantine pest, flavescence dorée (fdp), from the 16srv taxonomic group. the on-site detection of fdp with an affordable device would contribute to faster and more efficient decisions on the control measures for fdp. therefore, a real-time isothermal lamp assay for detection of fdp was validated according to the eppo standards and miqe guidelines. the lamp assay was shown to be specific and extremely ...201426146413
lamp assay and rapid sample preparation method for on-site detection of flavescence dorée phytoplasma in grapevine.in europe the most devastating phytoplasma associated with grapevine yellows (gy) diseases is a quarantine pest, flavescence dorée (fdp), from the 16srv taxonomic group. the on-site detection of fdp with an affordable device would contribute to faster and more efficient decisions on the control measures for fdp. therefore, a real-time isothermal lamp assay for detection of fdp was validated according to the eppo standards and miqe guidelines. the lamp assay was shown to be specific and extremely ...201426146413
killing two birds with one stone: trans-kingdom suppression of pamp/mamp-induced immunity by t3e from enteropathogenic bacteria.within the past decade, remarkable similarities between the molecular organization of animal and plant systems for non-self discrimination were revealed. obvious parallels exist between the molecular structures of the receptors mediating the recognition of pathogen- or microbe-associated molecular patterns (pamps/mamps) with plant pattern recognition receptors strikingly resembling mammalian toll-like receptors. mitogen-activated protein kinase cascades, leading to the transcriptional activation ...201425101059
genome-wide identification of mapkk and mapkkk gene families in tomato and transcriptional profiling analysis during development and stress response.mitogen-activated protein kinase (mapk) cascades have important functions in plant growth, development, and response to various stresses. the mapkk and mapkkk gene families in tomato have never been systematically analyzed. in this study, we performed a genome-wide analysis of the mapkk and mapkkk gene families in tomato and identified 5 mapkk genes and 89 mapkkk genes. phylogenetic analyses of the mapkk and mapkkk gene families showed that all the mapkk genes formed four groups (groups a, b, c, ...201425036993
sucrose and invertases, a part of the plant defense response to the biotic stresses.sucrose is the main form of assimilated carbon which is produced during photosynthesis and then transported from source to sink tissues via the phloem. this disaccharide is known to have important roles as signaling molecule and it is involved in many metabolic processes in plants. essential for plant growth and development, sucrose is engaged in plant defense by activating plant immune responses against pathogens. during infection, pathogens reallocate the plant sugars for their own needs forci ...201425002866
interactions of seedborne bacterial pathogens with host and non-host plants in relation to seed infestation and seedling transmission.the ability of seed-borne bacterial pathogens (acidovorax citrulli, clavibacter michiganensis subsp. michiganensis, pseudomonas syringae pv. tomato, xanthomonas euvesicatoria, and pseudomonas syringae pv. glycinea) to infest seeds of host and non-host plants (watermelon, tomato, pepper, and soybean) and subsequent pathogen transmission to seedlings was investigated. a non-pathogenic, pigmented strain of serratia marcescens was also included to assess a null-interacting situation with the same pl ...201424936863
the cuticle and plant defense to pathogens.the cuticle provides a physical barrier against water loss and protects against irradiation, xenobiotics, and pathogens. components of the cuticle are perceived by invading fungi and activate developmental processes during pathogenesis. in addition, cuticle alterations of various types induce a syndrome of reactions that often results in resistance to necrotrophs. this article reviews the current knowledge on the role of the cuticle in relation to the perception of pathogens and activation of de ...201424982666
intervention of phytohormone pathways by pathogen effectors.the constant struggle between plants and microbes has driven the evolution of multiple defense strategies in the host as well as offense strategies in the pathogen. to defend themselves from pathogen attack, plants often rely on elaborate signaling networks regulated by phytohormones. in turn, pathogens have adopted innovative strategies to manipulate phytohormone-regulated defenses. tactics frequently employed by plant pathogens involve hijacking, evading, or disrupting hormone signaling pathwa ...201424920334
searchdogs bacteria, software that provides automated identification of potentially missed genes in annotated bacterial genomes.we report the development of searchdogs bacteria, software to automatically detect missing genes in annotated bacterial genomes by combining blast searches with comparative genomics. having successfully applied the approach to yeast genomes, we redeveloped searchdogs to function as a standalone, downloadable package, requiring only a set of genbank annotation files as input. the software automatically generates a homology structure using reciprocal blast and a synteny-based method; this is follo ...201424659774
genome-wide identification of hfq-regulated small rnas in the fire blight pathogen erwinia amylovora discovered small rnas with virulence regulatory function.erwinia amylovora is a phytopathogenic bacterium and causal agent of fire blight disease in apples and pears. although many virulence factors have been characterized, the coordination of expression of these virulence factors in e. amylovora is still not clear. regulatory small rnas (srnas) are important post-transcriptional regulatory components in bacteria. a large number of srnas require the rna chaperone hfq for both stability and functional activation. in e. amylovora, hfq was identified as ...201424885615
analysis of phaseolus vulgaris response to its association with trichoderma harzianum (all-42) in the presence or absence of the phytopathogenic fungi rhizoctonia solani and fusarium solani.the present study was carried out to evaluate the ability of trichoderma harzianum (all 42-isolated from brazilian cerrado soil) to promote common bean growth and to modulate its metabolism and defense response in the presence or absence of the phytopathogenic fungi rhizoctonia solani and fusarium solani using a proteomic approach. t. harzianum was able to promote common bean plants growth as shown by the increase in root/foliar areas and by size in comparison to plants grown in its absence. the ...201424878929
analysis of the pantoea ananatis pan-genome reveals factors underlying its ability to colonize and interact with plant, insect and vertebrate hosts.pantoea ananatis is found in a wide range of natural environments, including water, soil, as part of the epi- and endophytic flora of various plant hosts, and in the insect gut. some strains have proven effective as biological control agents and plant-growth promoters, while other strains have been implicated in diseases of a broad range of plant hosts and humans. by analysing the pan-genome of eight sequenced p. ananatis strains isolated from different sources we identified factors potentially ...201424884520
chp8, a diguanylate cyclase from pseudomonas syringae pv. tomato dc3000, suppresses the pathogen-associated molecular pattern flagellin, increases extracellular polysaccharides, and promotes plant immune evasion.the bacterial plant pathogen pseudomonas syringae causes disease in a wide range of plants. the associated decrease in crop yields results in economic losses and threatens global food security. competition exists between the plant immune system and the pathogen, the basic principles of which can be applied to animal infection pathways. p. syringae uses a type iii secretion system (t3ss) to deliver virulence factors into the plant that promote survival of the bacterium. the p. syringae t3ss is a ...201424846383
growth-defense tradeoffs in plants: a balancing act to optimize fitness.growth-defense tradeoffs are thought to occur in plants due to resource restrictions, which demand prioritization towards either growth or defense, depending on external and internal factors. these tradeoffs have profound implications in agriculture and natural ecosystems, as both processes are vital for plant survival, reproduction, and, ultimately, plant fitness. while many of the molecular mechanisms underlying growth and defense tradeoffs remain to be elucidated, hormone crosstalk has emerge ...201424777989
functionally redundant rxlr effectors from phytophthora infestans act at different steps to suppress early flg22-triggered immunity.genome sequences of several economically important phytopathogenic oomycetes have revealed the presence of large families of so-called rxlr effectors. functional screens have identified rxlr effector repertoires that either compromise or induce plant defense responses. however, limited information is available about the molecular mechanisms underlying the modes of action of these effectors in planta. the perception of highly conserved pathogen- or microbe-associated molecular patterns (pamps/mam ...201424763622
rapid and sensitive detection of candidatus liberibacter asiaticus by loop mediated isothermal amplification combined with a lateral flow dipstick.citrus huanglongbing (hlb) is the most devastating bacterial citrus disease worldwide. three candidatus liberibacter species are associated with different forms of the disease: candidatus liberibacter asiaticus, candidatus liberibacter americanus and candidatus liberibacter africanus. amongst them, candidatus liberibacter asiaticus is the most widespread and economically important. these gram-negative bacterial plant pathogens are phloem-limited and vectored by citrus psyllids. the current manag ...201424708539
salmonella enterica induces and subverts the plant immune system.infections with salmonella enterica belong to the most prominent causes of food poisoning and infected fruits and vegetables represent important vectors for salmonellosis. although it was shown that plants raise defense responses against salmonella, these bacteria persist and proliferate in various plant tissues. recent reports shed light into the molecular interaction between plants and salmonella, highlighting the defense pathways induced and the means used by the bacteria to escape the plant ...201424772109
an important role of the pepper phenylalanine ammonia-lyase gene (pal1) in salicylic acid-dependent signalling of the defence response to microbial pathogens.phenylalanine ammonia-lyase (pal) has a crucial role in secondary phenylpropanoid metabolism and is one of the most extensively studied enzymes with respect to plant responses to biotic and abiotic stress. here, we identified the pepper (capsicum annuum) pal (capal1) gene, which was induced in pepper leaves by avirulent xanthomonas campestris pv. vesicatoria (xcv) infection. capal1-silenced pepper plants exhibited increased susceptibility to virulent and avirulent xcv infection. reactive oxygen ...201424642849
physiological and molecular implications of plant polyamine metabolism during biotic interactions.during ontogeny, plants interact with a wide variety of microorganisms. the association with mutualistic microbes results in benefits for the plant. by contrast, pathogens may cause a remarkable impairment of plant growth and development. both types of plant-microbe interactions provoke notable changes in the polyamine (pa) metabolism of the host and/or the microbe, being each interaction a complex and dynamic process. it has been well documented that the levels of free and conjugated pas underg ...201424672533
evaluation of antibacterial and cytotoxic activity of artemisia nilagirica and murraya koenigii leaf extracts against mycobacteria and macrophages.artemisia nilagirica (asteraceae) and murraya koenigii (rutaceae) are widely distributed in eastern region of india. leaves of artemisia nilagirica plant are used to treat cold and cough by the local tribal population in east india. murraya koenigii is an edible plant previously reported to have an antibacterial activity. pathogenic strains of mycobacteria are resistant to most of the conventional antibiotics. therefore, it is imperative to identify novel antimycobacterial molecules to treat myc ...201424597853
small non-coding rnas in plant-pathogenic xanthomonas spp.the genus xanthomonas comprises a large group of plant-pathogenic bacteria. the infection and bacterial multiplication in the plant tissue depends on the type iii secretion system and other virulence determinants. recent studies revealed that bacterial virulence is also controlled at the post-transcriptional level by small non-coding rnas (srnas). in this review, we highlight our current knowledge about srnas and rna-binding proteins in xanthomonas species.201424667380
transgenic expression of the rice xa21 pattern-recognition receptor in banana (musa sp.) confers resistance to xanthomonas campestris pv. musacearum.banana xanthomonas wilt (bxw), caused by the bacterium xanthomonas campestris pv. musacearum (xcm), is the most devastating disease of banana in east and central africa. the spread of bxw threatens the livelihood of millions of african farmers who depend on banana for food security and income. there are no commercial chemicals, biocontrol agents or resistant cultivars available to control bxw. here, we take advantage of the robust resistance conferred by the rice pattern-recognition receptor (pr ...201424612254
type iv secretion system is not involved in infection process in citrus.the type iv secretion system (t4ss) is used by gram-negative bacteria to translocate protein and dna substrates across the cell envelope and into target cells. xanthomonas citri subsp. citri contains two copies of the t4ss, one in the chromosome and the other is plasmid-encoded. to understand the conditions that induce expression of the t4ss in xcc, we analyzed, in vitro and in planta, the expression of 18 orfs from the t4ss and 7 hypothetical flanking genes by rt-qpcr. as a positive control, we ...201424707292
the factors affecting effectiveness of treatment in phages therapy.in recent years, the use of lytic bacteriophages as antimicrobial agents controlling pathogenic bacteria has appeared as a promising new alternative strategy in the face of growing antibiotic resistance which has caused problems in many fields including medicine, veterinary medicine, and aquaculture. the use of bacteriophages has numerous advantages over traditional antimicrobials. the effectiveness of phage applications in fighting against pathogenic bacteria depends on several factors such as ...201424600439
regulation of primary plant metabolism during plant-pathogen interactions and its contribution to plant defense.plants are constantly exposed to microorganisms in the environment and, as a result, have evolved intricate mechanisms to recognize and defend themselves against potential pathogens. one of these responses is the downregulation of photosynthesis and other processes associated with primary metabolism that are essential for plant growth. it has been suggested that the energy saved by downregulation of primary metabolism is diverted and used for defense responses. however, several studies have show ...201424575102
pathogenic adaptations to host-derived antibacterial copper.recent findings suggest that both host and pathogen manipulate copper content in infected host niches during infections. in this review, we summarize recent developments that implicate copper resistance as an important determinant of bacterial fitness at the host-pathogen interface. an essential mammalian nutrient, copper cycles between copper (i) (cu(+)) in its reduced form and copper (ii) (cu(2+)) in its oxidized form under physiologic conditions. cu(+) is significantly more bactericidal than ...201424551598
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