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expressing the erwinia amylovora type iii effector dspa/e in the yeast saccharomyces cerevisiae strongly alters cellular trafficking.erwinia amylovora is responsible for fire blight, a necrotic disease of apples and pears. e. amylovora relies on a type iii secretion system (t3ss) to induce disease on host plants. dspa/e belongs to the avre family of type iii effector. effectors of the avre family are injected via the t3ss in plant cell and are important to promote bacterial growth following infection and to suppress plant defense responses. their mode of action in the plant cells is unknown. here we study the physiological ef ...201123650572
calcium-dependent protein kinase/nadph oxidase activation circuit is required for rapid defense signal propagation.in animals and plants, pathogen recognition triggers the local activation of intracellular signaling that is prerequisite for mounting systemic defenses in the whole organism. we identified that arabidopsis thaliana isoform cpk5 of the plant calcium-dependent protein kinase family becomes rapidly biochemically activated in response to pathogen-associated molecular pattern (pamp) stimulation. cpk5 signaling resulted in enhanced salicylic acid-mediated resistance to the bacterial pathogen pst dc30 ...201323650383
wrky8 transcription factor functions in the tmv-cg defense response by mediating both abscisic acid and ethylene signaling in arabidopsis.wrky transcription factors are key players in the plant immune response, but less is known about their involvement in antiviral defense than about their roles in defense against bacterial or fungi pathogens. here, we report that arabidopsis thaliana wrky dna-binding protein 8 (wrky8) has a role in mediating the long-distance movement of crucifer-infecting tobacco mosaic virus (tmv-cg). the expression of wrky8 was inhibited by tmv-cg infection, and mutation of wrky8 accelerated the accumulation o ...201323650359
combined effect of a peptide-morpholino oligonucleotide conjugate and a cell-penetrating peptide as an antibiotic.a cell-penetrating peptide (cpp)-morpholino oligonucleotide (mo) conjugate (pmo) that has an antibiotic effect in culture had some contaminating cpps in earlier preparations. the mixed conjugate had gene-specific and gene-nonspecific effects. an improved purification procedure separates the pmo from the free cpp and mo. the gene-specific effects are a result of the pmo, and the nonspecific effects are a result of the unlinked, unreacted cpp. the pmo and the cpp can be mixed together, as has been ...201323650357
genome-wide organization and expression profiling of the nac transcription factor family in potato (solanum tuberosum l.).nac [no apical meristem (nam), arabidopsis thaliana transcription activation factor [ataf1/2] and cup-shaped cotyledon (cuc2)] proteins belong to one of the largest plant-specific transcription factor (tf) families and play important roles in plant development processes, response to biotic and abiotic cues and hormone signalling. our genome-wide analysis identified 110 stnac genes in potato encoding for 136 proteins, including 14 membrane-bound tfs. the physical map positions of stnac genes on 1 ...201323649897
ubiquitin-specific proteases ubp12 and ubp13 act in circadian clock and photoperiodic flowering regulation in arabidopsis.protein ubiquitination is involved in most cellular processes. in arabidopsis (arabidopsis thaliana), ubiquitin-mediated protein degradation regulates the stability of key components of the circadian clock feedback loops and the photoperiodic flowering pathway. here, we identified two ubiquitin-specific proteases, ubp12 and ubp13, involved in circadian clock and photoperiodic flowering regulation. double mutants of ubp12 and ubp13 display pleiotropic phenotypes, including early flowering and sho ...201323645632
drought stress acclimation imparts tolerance to sclerotinia sclerotiorum and pseudomonas syringae in nicotiana benthamiana.acclimation of plants with an abiotic stress can impart tolerance to some biotic stresses. such a priming response has not been widely studied. in particular, little is known about enhanced defense capacity of drought stress acclimated plants to fungal and bacterial pathogens. here we show that prior drought acclimation in nicotiana benthamiana plants imparts tolerance to necrotrophic fungus, sclerotinia sclerotiorum, and also to hemi-biotrophic bacterial pathogen, pseudomonas syringae pv. tabac ...201323644883
high cytokinin levels induce a hypersensitive-like response in tobacco.cytokinins are positive regulators of shoot development. however, it has previously been demonstrated that efficient activation of the cytokinin biosynthesis gene ipt can cause necrotic lesions and wilting in tobacco leaves. some plant pathogens reportedly use their ability to produce cytokinins in disease development. in response to pathogen attacks, plants can trigger a hypersensitive response that rapidly kills cells near the infection site, depriving the pathogen of nutrients and preventing ...201323644362
comparative genome analysis of burkholderia phytofirmans psjn reveals a wide spectrum of endophytic lifestyles based on interaction strategies with host plants.burkholderia phytofirmans psjn is a naturally occurring plant-associated bacterial endophyte that effectively colonizes a wide range of plants and stimulates their growth and vitality. here we analyze whole genomes, of psjn and of eight other endophytic bacteria. this study illustrates that a wide spectrum of endophytic life styles exists. although we postulate the existence of typical endophytic traits, no unique gene cluster could be exclusively linked to the endophytic lifestyle. furthermore, ...201323641251
prospects for advancing defense to cereal rusts through genetical genomics.rusts are one of the most severe threats to cereal crops because new pathogen races emerge regularly, resulting in infestations that lead to large yield losses. in 1999, a new race of stem rust, puccinia graminis f. sp. tritici (pgt ttksk or ug99), was discovered in uganda. most of the wheat and barley cultivars grown currently worldwide are susceptible to this new race. pgt ttksk has already spread northward into iran and will likely spread eastward throughout the indian subcontinent in the nea ...201323641250
coronatine inhibits stomatal closure and delays hypersensitive response cell death induced by nonhost bacterial pathogens.pseudomonas syringae is the most widespread bacterial pathogen in plants. several strains of p. syringae produce a phytotoxin, coronatine (cor), which acts as a jasmonic acid mimic and inhibits plant defense responses and contributes to disease symptom development. in this study, we found that cor inhibits early defense responses during nonhost disease resistance. stomatal closure induced by a nonhost pathogen, p. syringae pv. tabaci, was disrupted by cor in tomato epidermal peels. in addition, ...201323638370
reduced expression of glycolate oxidase leads to enhanced disease resistance in rice.glycolate oxidase (glo) is a key enzyme in photorespiration, catalyzing the oxidation of glycolate to glyoxylate. arabidopsis glo is required for nonhost defense responses to pseudomonas syringae and for tobacco pto/avrpto-mediated defense responses. we previously described identification of rice glo1 that interacts with a glutaredoxin protein, which in turn interacts with tga transcription factors. tga transcription factors are well known to participate in npr1/nh1-mediated defense signaling, w ...201323638363
exopolymer diversity and the role of levan in bacillus subtilis biofilms.exopolymeric substances (eps) are important for biofilm formation and their chemical composition may influence biofilm properties. to explore these relationships the chemical composition of eps from bacillus subtilis ncib 3610 biofilms grown in sucrose-rich (sym) and sucrose-poor (msgg and czapek) media was studied. we observed marked differences in composition of eps polymers isolated from all three biofilms or from spent media below the biofilms. the polysaccharide levan dominated the eps of s ...201323637960
identification of genes and pathways related to phenol degradation in metagenomic libraries from petroleum refinery wastewater.two fosmid libraries, totaling 13,200 clones, were obtained from bioreactor sludge of petroleum refinery wastewater treatment system. the library screening based on pcr and biological activity assays revealed more than 400 positive clones for phenol degradation. from these, 100 clones were randomly selected for pyrosequencing in order to evaluate the genetic potential of the microorganisms present in wastewater treatment plant for biodegradation, focusing mainly on novel genes and pathways of ph ...201323637911
cytotoxic chromosomal targeting by crispr/cas systems can reshape bacterial genomes and expel or remodel pathogenicity islands.in prokaryotes, clustered regularly interspaced short palindromic repeats (crisprs) and their associated (cas) proteins constitute a defence system against bacteriophages and plasmids. crispr/cas systems acquire short spacer sequences from foreign genetic elements and incorporate these into their crispr arrays, generating a memory of past invaders. defence is provided by short non-coding rnas that guide cas proteins to cleave complementary nucleic acids. while most spacers are acquired from phag ...201323637624
mutations in fls2 ser-938 dissect signaling activation in fls2-mediated arabidopsis immunity.flagellin-sensing 2 (fls2) is a leucine-rich repeat/transmembrane domain/protein kinase (lrr-rlk) that is the plant receptor for bacterial flagellin or the flagellin-derived flg22 peptide. previous work has shown that after flg22 binding, fls2 releases bik1 kinase and homologs and associates with bak1 kinase, and that fls2 kinase activity is critical for fls2 function. however, the detailed mechanisms for activation of fls2 signaling remain unclear. the present study initially identified multipl ...201323637603
genetic requirements for signaling from an autoactive plant nb-lrr intracellular innate immune receptor.plants react to pathogen attack via recognition of, and response to, pathogen-specific molecules at the cell surface and inside the cell. pathogen effectors (virulence factors) are monitored by intracellular nucleotide-binding leucine-rich repeat (nb-lrr) sensor proteins in plants and mammals. here, we study the genetic requirements for defense responses of an autoactive mutant of adr1-l2, an arabidopsis coiled-coil (cc)-nb-lrr protein. adr1-l2 functions upstream of salicylic acid (sa) accumulat ...201323633962
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
identification of lens culinaris defense genes responsive to the anthracnose pathogen colletotrichum truncatum.anthracnose of lentil, caused by the hemibiotrophic fungal pathogen colletotrichum truncatum is a serious threat to lentil production in western canada. colletotrichum truncatum employs a bi-phasic infection strategy characterized by initial symptomless biotrophic and subsequent destructive necrotrophic colonization of its host. the transition from biotrophy to necrotrophy (known as the biotrophy-necrotrophy switch [bns]) is critical in anthracnose development. understanding plant responses duri ...201323631759
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
plant systemic induced responses mediate interactions between root parasitic nematodes and aboveground herbivorous insects.insects and nematodes are the most diverse and abundant groups of multicellular animals feeding on plants on either side of the soil-air interface. several herbivore-induced responses are systemic, and hence can influence the preference and performance of organisms in other plant organs. recent studies show that plants mediate interactions between belowground plant parasitic nematodes (ppns) and aboveground herbivorous insects. based on the knowledge of plant responses to pathogens, we review th ...201323630532
e-2-hexenal promotes susceptibility to pseudomonas syringae by activating jasmonic acid pathways in arabidopsis.green leaf volatiles (glvs) are c6-molecules - alcohols, aldehydes, and esters - produced by plants upon herbivory or during pathogen infection. exposure to this blend of volatiles induces defense-related responses in neighboring undamaged plants, thus assigning a role to glvs in regulating plant defenses. here we compared arabidopsis thaliana ecotype landsberg erecta (ler) with a hydroperoxide lyase line, hpl1, unable to synthesize glvs, for susceptibility to pseudomonas syringae pv. tomato (dc ...201323630530
reducing asa leads to leaf lesion and defence response in knock-down of the asa biosynthetic enzyme gdp-d-mannose pyrophosphorylase gene in tomato plant.as a vital antioxidant, l-ascorbic acid (asa) affects diverse biological processes in higher plants. lack of asa in cell impairs plant development. in the present study, we manipulated a gene of gdp-mannose pyrophosphorylase which catalyzes the conversion of d-mannose-1-p to gdp-d-mannose in asa biosynthetic pathway and found out the phenotype alteration of tomato. in the tomato genome, there are four members of gmp gene family and they constitutively expressed in various tissues in distinct exp ...201323626761
novel α-msh peptide analogues with broad spectrum antimicrobial activity.previous investigations indicate that α-melanocyte-stimulating hormone (α-msh) and certain synthetic analogues of it exert antimicrobial effects against bacteria and yeasts. however, these molecules have weak activity in standard microbiology conditions and this hampers a realistic clinical use. the aim in the present study was to identify novel peptides with broad-spectrum antimicrobial activity in growth medium. to this purpose, the gly10 residue in the [dnal(2')-7, phe-12]-msh(6-13) sequence ...201323626703
binding protein is a master regulator of the endoplasmic reticulum stress sensor/transducer bzip28 in arabidopsis.binding protein (bip) is a major chaperone in the endoplasmic reticulum (er) lumen, and this study shows that bip binds to the c-terminal tail of the stress sensor/transducer bzip28, a membrane-associated transcription factor, retaining it in the er under unstressed conditions. in response to er stress, bip dissociates from bzip28, allowing it to be mobilized from the er to the golgi where it is proteolytically processed and released to enter the nucleus. under unstressed conditions, bip binds t ...201323624714
genome-wide identification and functional analyses of calmodulin genes in solanaceous species.calmodulin (cam) is a major calcium sensor in all eukaryotes. it binds calcium and modulates the activity of a wide range of downstream proteins in response to calcium signals. however, little is known about the cam gene family in solanaceous species, including the economically important species, tomato (solanum lycopersicum), and the gene silencing model plant, nicotiana benthamiana. moreover, the potential function of cam in plant disease resistance remains largely unclear.201323621884
dual action of bpc194: a membrane active peptide killing bacterial cells.membrane active peptides can perturb the lipid bilayer in several ways, such as poration and fusion of the target cell membrane, and thereby efficiently kill bacterial cells. we probe here the mechanistic basis of membrane poration and fusion caused by membrane-active, antimicrobial peptides. we show that the cyclic antimicrobial peptide, bpc194, inhibits growth of gram-negative bacteria and ruptures the outer and inner membrane at the onset of killing, suggesting that not just poration is takin ...201323620763
sensing temperature.temperature is an omnipresent physical variable reflecting the rotational, vibrational and translational motion of matter, what richard feynman called the "jiggling" of atoms. temperature varies across space and time, and this variation has dramatic effects on the physiology of living cells. it changes the rate and nature of chemical reactions, and it alters the configuration of the atoms that make up nucleic acids, proteins, lipids and other biomolecules, significantly affecting their activity. ...201323618661
ectopic expression of atpad4 broadens resistance of soybean to soybean cyst and root-knot nematodes.the gene encoding pad4 (phytoalexin-deficient4) is required in arabidopsis for expression of several genes involved in the defense response to pseudomonas syringae pv. maculicola. atpad4 (arabidopsis thaliana pad4) encodes a lipase-like protein that plays a regulatory role mediating salicylic acid signaling.201323617694
a tir-nbs protein encoded by arabidopsis chilling sensitive 1 (chs1) limits chloroplast damage and cell death at low temperature.survival of plants at low temperature depends on mechanisms for limiting physiological damage and maintaining growth. we mapped the chs1-1 (chilling sensitive1-1) mutation in arabidopsis accession columbia to the tir-nbs gene at1g17610. in chs1-1, a single amino acid exchange at the chs1 n-terminus close to the conserved tir domain creates a stable mutant protein that fails to protect leaves against chilling stress. the sequence of another tir-nbs gene (at5g40090) named chl1 (chs1-like 1) is rel ...201323617639
current knowledge on the ralstonia solanacearum type iii secretion system. 201323617636
analyses of wrky18 wrky40 plants reveal critical roles of sa/eds1 signaling and indole-glucosinolate biosynthesis for golovinomyces orontii resistance and a loss-of resistance towards pseudomonas syringae pv. tomato avrrps4.simultaneous mutation of two wrky-type transcription factors, wrky18 and wrky40, renders otherwise susceptible wild-type arabidopsis plants resistant towards the biotrophic powdery mildew fungus golovinomyces orontii. resistance in wrky18 wrky40 double mutant plants is accompanied by massive transcriptional reprogramming, imbalance in salicylic acid (sa) and jasmonic acid (ja) signaling, altered enhanced disease susceptibility1 (eds1) expression, and accumulation of the phytoalexin camalexin. ge ...201323617415
pseudomonas syringae infection assays in arabidopsis.pseudomonas syringae pv. tomato dc30000 (pst dc3000) infection of arabidopsis thaliana has been widely used to elucidate many of the general principles underlying the plant immune response and bacterial pathogenesis. study of pst dc3000 virulence factors has also proven useful in the discovery and elucidation of fundamental mechanisms in plant biology. in particular, pst dc3000 produces a phytotoxin, coronatine, that is a remarkable molecular mimic of the active form of the plant hormone jasmona ...201323615988
bioassays for assessing jasmonate-dependent defenses triggered by pathogens, herbivorous insects, or beneficial rhizobacteria.jasmonates, together with other plant hormones, are important orchestrators of the plant immune system. the different hormone-controlled signaling pathways cross-communicate in an antagonistic or a synergistic manner, providing the plant with a powerful capacity to finely regulate its immune response. jasmonic acid (ja) signaling is required for plant resistance to harmful organisms, such as necrotrophic pathogens and herbivorous insects. furthermore, ja signaling is essential in interactions of ...201323615986
bioactive molecules in soil ecosystems: masters of the underground.complex biological and ecological processes occur in the rhizosphere through ecosystem-level interactions between roots, microorganisms and soil fauna. over the past decade, studies of the rhizosphere have revealed that when roots, microorganisms and soil fauna physically contact one another, bioactive molecular exchanges often mediate these interactions as intercellular signal, which prepare the partners for successful interactions. despite the importance of bioactive molecules in sustainable a ...201323615474
the brassinosteroid signaling pathway-new key players and interconnections with other signaling networks crucial for plant development and stress tolerance.brassinosteroids (brs) are a class of steroid hormones regulating a wide range of physiological processes during the plant life cycle from seed development to the modulation of flowering and senescence. the last decades, and recent years in particular, have witnessed a significant advance in the elucidation of the molecular mechanisms of br signaling from perception by the transmembrane receptor complex to the regulation of transcription factors influencing expression of the target genes. applic ...201323615468
partial disruption of translational and posttranslational machinery reshapes growth rates of bartonella birtlesii.specialization of bacteria in a new niche is associated with genome repertoire changes, and speciation in bacterial specialists is associated with genome reduction. here, we tested a signature-tagged mutant library of 3,456 bartonella birtlesii clones to detect mutants that could grow rapidly in vitro. overall, we found 124 mutants that grew faster than the parental wild-type strain in vitro. we sequenced the genomes of the four mutants with the most rapid growth (formed visible colonies in only ...201323611908
the arabidopsis mediator complex subunits med14/swp and med16/sfr6/ien1 differentially regulate defense gene expression in plant immune responses.pathogen infection in plants triggers large-scale transcriptional changes, both locally and systemically. emerging evidence suggests that the arabidopsis mediator complex plays a crucial role in these transcriptional changes. mediator is highly conserved in eukaryotes, and its core comprises more than 20 subunits organized into three modules named head, middle and tail. the head and middle modules interact with general transcription factors and rna polymerase ii, whereas the tail module associat ...201323607369
comparative genomic analysis of four representative plant growth-promoting rhizobacteria in pseudomonas.some pseudomonas strains function as predominant plant growth-promoting rhizobacteria (pgpr). within this group, pseudomonas chlororaphis and pseudomonas fluorescens are non-pathogenic biocontrol agents, and some pseudomonas aeruginosa and pseudomonas stutzeri strains are pgpr. p. chlororaphis gp72 is a plant growth-promoting rhizobacterium with a fully sequenced genome. we conducted a genomic analysis comparing gp72 with three other pseudomonad pgpr: p. fluorescens pf-5, p. aeruginosa m18, and ...201323607266
just in time: circadian defense patterns and the optimal defense hypothesis.the optimal defense hypothesis (odh) provides a functional explanation for the inhomogeneous distribution of defensive structures and defense metabolites throughout a plant's body: tissues that are most valuable in terms of fitness and have the highest probability of attack are generally the best defended. in a previous review, we argue that ontogenically-controlled accumulations of defense metabolites are likely regulated through an integration of developmental and defense signaling pathways. i ...201323603968
direct regulation of wrky70 by atmyb44 in plant defense responses.cross-talk between hormones is required for plant response to developmental cues and environmental stresses. this cross-talk is achieved through several regulators located in convergence point of distinct hormonal signaling. in plant defense responses, salicylic acid and jasmonic acid affect each other in antagonistic manner. in a recent study we showed that atmyb44 transcription factor positively regulates sa-mediated defense expression and enhanced resistance to pst dc3000. on the other hand, ...201323603962
one shot-two pathogens blocked: exposure of arabidopsis to hexadecane, a long chain volatile organic compound, confers induced resistance against both pectobacterium carotovorum and pseudomonas syringae.bacteria and plant derived volatile organic compounds have been reported as the chemical triggers that elicit induced resistance in plants. previously, volatile organic compounds (vocs), including acetoin and 2,3-butanediol, were found to be emitted from plant growth-promoting rhizobacteria (pgpr) bacillus subtilis gb03, which had been shown to elicit isr and plant growth promotion. more recently, we reported data that stronger induced resistance could be elicited against pseudomonas syringae pv ...201323603940
dechlorination of chloral hydrate is influenced by the biofilm adhesin protein lapa in pseudomonas putida lf54.lapa is the largest surface adhesion protein of pseudomonas putida that initiates biofilm formation. here, by using transposon insertion mutagenesis and a conditional lapa mutant, we demonstrate for the first time that lapa influences chloral hydrate (ch) dechlorination in p. putida lf54.201323603683
evolution and variability of solanum rangap2, a cofactor in the incompatible interaction between the resistance protein gpa2 and the globodera pallida effector gp-rbp-1.the ran gtpase activating protein 2 (rangap2) was first described as a regulator of mitosis and nucleocytoplasmic trafficking. it was then found to interact with the coiled-coil domain of the rx and gpa2 resistance proteins, which confer resistance to potato virus x (pvx) and potato cyst nematode globodera pallida, respectively. rangap2 is thought to mediate recognition of the avirulence protein gp-rbp-1 by gpa2. however, the gpa2-induced hypersensitive response appears to be relatively weak and ...201323601377
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
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
a nuclear localization for avr2 from fusarium oxysporum is required to activate the tomato resistance protein i-2.plant pathogens secrete effector proteins to promote host colonization. during infection of tomato xylem vessels, fusarium oxysporum f. sp. lycopersici (fol) secretes the avr2 effector protein. besides being a virulence factor, avr2 is recognized intracellularly by the tomato i-2 resistance protein, resulting in the induction of host defenses. here, we show that avr2 is highly expressed in root- and xylem-colonizing hyphae three days post inoculation of roots. co-expression of i-2 with avr2 dele ...201323596453
functional redundancy and divergence within the arabidopsis reticulata-related gene family.a number of arabidopsis (arabidopsis thaliana) mutants exhibit leaf reticulation, having green veins that stand out against paler interveinal tissues, fewer cells in the interveinal mesophyll, and normal perivascular bundle sheath cells. here, to examine the basis of leaf reticulation, we analyzed the arabidopsis reticulata-related (rer) gene family, several members of which cause leaf reticulation when mutated. although transcripts of re, rer1, and rer3 were mainly detected in the bundle sheath ...201323596191
the phytophthora parasitica rxlr effector penetration-specific effector 1 favours arabidopsis thaliana infection by interfering with auxin physiology.pathogenic oomycetes have evolved rxlr effectors to thwart plant defense mechanisms and invade host tissues. we analysed the function of one of these effectors (penetration-specific effector 1 (pse1)) whose transcript is transiently accumulated during penetration of host roots by the oomycete phytophthora parasitica. expression of pse1 protein in tobacco (nicotiana tabacum and nicotiana benthamiana) leaves and in arabidopsis thaliana plants was used to assess the role of this effector in plant p ...201323594295
the plant actin cytoskeleton responds to signals from microbe-associated molecular patterns.plants are constantly exposed to a large and diverse array of microbes; however, most plants are immune to the majority of potential invaders and susceptible to only a small subset of pathogens. the cytoskeleton comprises a dynamic intracellular framework that responds rapidly to biotic stresses and supports numerous fundamental cellular processes including vesicle trafficking, endocytosis and the spatial distribution of organelles and protein complexes. for years, the actin cytoskeleton has bee ...201323593000
cell death control: the interplay of apoptosis and autophagy in the pathogenicity of sclerotinia sclerotiorum.programmed cell death is characterized by a cascade of tightly controlled events that culminate in the orchestrated death of the cell. in multicellular organisms autophagy and apoptosis are recognized as two principal means by which these genetically determined cell deaths occur. during plant-microbe interactions cell death programs can mediate both resistant and susceptible events. via oxalic acid (oa), the necrotrophic phytopathogen sclerotinia sclerotiorum hijacks host pathways and induces ce ...201323592997
light-induced acclimation of the arabidopsis chlorina1 mutant to singlet oxygen.singlet oxygen (¹o₂) is a reactive oxygen species that can function as a stress signal in plant leaves leading to programmed cell death. in microalgae, ¹o₂-induced transcriptomic changes result in acclimation to ¹o₂. here, using a chlorophyll b-less arabidopsis thaliana mutant (chlorina1 [ch1]), we show that this phenomenon can also occur in vascular plants. the ch1 mutant is highly photosensitive due to a selective increase in the release of ¹o₂ by photosystem ii. under photooxidative stress co ...201323590883
exploitation of eukaryotic subcellular targeting mechanisms by bacterial effectors.several bacterial species have evolved specialized secretion systems to deliver bacterial effector proteins into eukaryotic cells. these effectors have the capacity to modulate host cell pathways in order to promote bacterial survival and replication. the spatial and temporal context in which the effectors exert their biochemical activities is crucial for their function. to fully understand effector function in the context of infection, we need to understand the mechanisms that lead to the preci ...201323588250
transcriptional profile of p. syringae pv. phaseolicola nps3121 at low temperature: physiology of phytopathogenic bacteria.low temperatures play key roles in the development of most plant diseases, mainly because of their influence on the expression of various virulence factors in phytopathogenic bacteria. thus far, studies regarding this environmental parameter have focused on specific themes and little is known about phytopathogenic bacteria physiology under these conditions. to obtain a global view regarding phytopathogenic bacteria strategies in response to physiologically relevant temperature changes, we used d ...201323587016
candidatus liberibacter americanus induces significant reprogramming of the transcriptome of the susceptible citrus genotype.citrus huanglongbing (hlb) disease is caused by endogenous, phloem-restricted, gram negative, uncultured bacteria named candidatus liberibacter africanus (calaf), ca. l. asiaticus (calas), and ca. l. americanus (calam), depending on the continent where the bacteria were first detected. the asian citrus psyllid vector, diaphorina citri, transmits calas and calam and both liberibacter species are present in brazil. several studies of the transcriptional response of citrus plants manifesting hlb sy ...201323586643
role of homeodomain leucine zipper (hd-zip) iv transcription factors in plant development and plant protection from deleterious environmental factors.homeobox genes comprise an important group of genes that are responsible for regulation of developmental processes. these genes determine cell differentiation and cell fate in all eukaryotic organisms, starting from the early stages of embryo development. homeodomain leucine zipper (hd-zip) transcription factors are unique to the plant kingdom. members of the hd-zip iv subfamily have a complex domain topology and can bind several cis-elements with overlapping sequences. many of the reported hd-z ...201323584027
new checkpoints in stomatal defense.recent reports have revealed new guard cell signaling elements that function in stomatal defense in arabidopsis thaliana (arabidopsis). we discuss here the role of oxylipins, salicylic acid (sa), and abscisic acid (aba) in stomatal immunity in response to the bacterial pathogen pseudomonas syringae.201323582764
proline mechanisms of stress survival.the imino acid proline is utilized by different organisms to offset cellular imbalances caused by environmental stress. the wide use in nature of proline as a stress adaptor molecule indicates that proline has a fundamental biological role in stress response. understanding the mechanisms by which proline enhances abiotic/biotic stress response will facilitate agricultural crop research and improve human health.201323581681
response of tobacco to the pseudomonas syringae pv. tomato dc3000 is mainly dependent on salicylic acid signaling pathway.pseudomonas syringae pv. tomato dc3000 (pst dc3000) was the first pathogen to be demonstrated to infect arabidopsis and to cause disease symptoms in the laboratory setting. however, the defense response to pst dc3000 was unclear in tobacco. in this report, the expression profiles of twelve defense response-related genes were analyzed after treatment with salicylic acid (sa), jasmonic acid (ja), and pathogen pst dc3000 by qrt-pcr. according to our results, it could be presented that the genes pri ...201323581479
comparative transcriptome analysis of gossypium hirsutum l. in response to sap sucking insects: aphid and whitefly.cotton (gossypium hirsutum l.) is a major fiber crop that is grown worldwide; it faces extensive damage from sap-sucking insects, including aphids and whiteflies. genome-wide transcriptome analysis was performed to understand the molecular details of interaction between gossypium hirsutum l. and sap-sucking pests, namely aphis gossypii (aphid) and bemisia tabacci (whiteflies). roche's gs-titanium was used to sequence transcriptomes of cotton infested with aphids and whiteflies for 2 h and 24 h.201323577705
arabidopsis phospholipase dβ1 modulates defense responses to bacterial and fungal pathogens.pathogen infection of higher plants often induces rapid production of phosphatidic acid (pa) and changes in lipid profiles, but the enzymatic basis and the function of the lipid change in pathogen-plant interactions are not well understood. infection of phospholipase d β1 (pldβ1)-deficient plants by pseudomonas syringae tomato pv dc3000 (pst dc30000) resulted in less bacterial growth than in wild-type plants, and the effect was more profound in virulent pst dc3000 than avirulent pst dc3000 (carr ...201323577648
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
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
effects of pesticides on the reduction of plant and human pathogenic bacteria in application water.overhead spray applications of in-field tomato treatments dissolved in aqueous solutions have specific pest targets (fungal, bacterial, insect, or other). any organism present in the solution or on treated plant surfaces that is not a specific target of the application is unlikely inactivated and can instead be spread through the phyllosphere. in this laboratory study, commercially labeled pesticides (including actigard 50wg, bravo weather stik 6f, cabrio 20eg, kasumin, kocide 3000 46wg, oxidate ...201323575141
antibacterial constituents of three cameroonian medicinal plants: garcinia nobilis, oricia suaveolens and balsamocitrus camerunensis.multidrug resistance is a worrying cause of treatment failure in bacterial infections. the search of bioactive constituents from medicinal plants against multidrug resistant (mdr) bacteria has significantly evolved in the two last decades. in the present study, twenty-two compounds (three terpenoids, eleven phenolics and eight alkaloids) isolated from three cameroonian medicinal plants, namely garcinia nobilis, oricia suaveolens and balsamocitrus camerunensis, as well as the crude extracts were ...201323574627
production of indole acetic acid by pseudomonas sp.: effect of coinoculation with mesorhizobium sp. cicer on nodulation and plant growth of chickpea (cicer arietinum).pseudomonas isolates obtained from the rhizosphere of chickpea (cicer arietinum l.) and green gram (vigna radiata) were found to produce significant amount of indole acetic acid (iaa) when grown in a lb medium broth supplemented with l-tryptophan. seed bacterization of chickpea cultivar c235 with different pseudomonas isolates showed stunting effect on the development of root and shoot at 5 and 10 days of seedling growth except the strains mps79 and mps90 that showed stimulation of root growth, ...201123572992
bacillus subtilis biofilm induction by plant polysaccharides.bacillus subtilis is a plant-beneficial gram-positive bacterium widely used as a biofertilizer. however, relatively little is known regarding the molecular processes underlying this bacterium's ability to colonize roots. in contrast, much is known about how this bacterium forms matrix-enclosed multicellular communities (biofilms) in vitro. here, we show that, when b. subtilis colonizes arabidopsis thaliana roots it forms biofilms that depend on the same matrix genes required in vitro. b. subtili ...201323569226
metabolite profiling and biological activities of bioactive compounds produced by chrysosporium lobatum strain bk-3 isolated from kaziranga national park, assam, india.in an ongoing survey for bioactive potential of microorganisms from different biosphere zones of india, a new chrysosporium lobatum strain bk-3 was isolated from soil sample collected from a biodiversity hotspot, kaziranga national park, assam, india. bioactivity-guided purification resulted in the isolation of two bioactive compounds whose chemical structures were elucidated by (1)h and (13)c nuclear magnetic resonance (nmr), 2d-nmr, fourier transform infra-red (ft-ir) and mass spectroscopic te ...201323565355
differential requirement of oryza sativa rar1 in immune receptor-mediated resistance of rice to magnaporthe oryzae.the required for mla12 resistance (rar1) protein is essential for the plant immune response. in rice, a model monocot species, the function of oryza sativa rar1 (osrar1) has been little explored. in our current study, we characterized the response of a rice osrar1 t-dna insertion mutant to infection by magnaporthe oryzae, the causal agent of rice blast disease. osrar1 mutants displayed reduced resistance compared with wild type rice when inoculated with the normally virulent m. oryzae isolate po ...201323563801
pattern-triggered immunity suppresses programmed cell death triggered by fumonisin b1.programmed cell death (pcd) is a crucial process for plant innate immunity and development. in plant innate immunity, pcd is believed to prevent the spread of pathogens from the infection site. although proper control of pcd is important for plant fitness, we have limited understanding of the molecular mechanisms regulating plant pcd. plant innate immunity triggered by recognition of effectors (effector-triggered immunity, eti) is often associated with pcd. however pattern-triggered immunity (pt ...201323560104
jasmonates: biosynthesis, perception, signal transduction and action in plant stress response, growth and development. an update to the 2007 review in annals of botany.jasmonates are important regulators in plant responses to biotic and abiotic stresses as well as in development. synthesized from lipid-constituents, the initially formed jasmonic acid is converted to different metabolites including the conjugate with isoleucine. important new components of jasmonate signalling including its receptor were identified, providing deeper insight into the role of jasmonate signalling pathways in stress responses and development.201323558912
the hopq1 effector's nucleoside hydrolase-like domain is required for bacterial virulence in arabidopsis and tomato, but not host recognition in tobacco.bacterial pathogens deliver multiple effector proteins into host cells to facilitate bacterial growth. hopq1 is an effector from pseudomonas syringae pv. tomato dc3000 that is conserved across multiple bacterial pathogens which infect plants. hopq1's central region possesses some homology to nucleoside hydrolases, but possesses an alternative aspartate motif not found in characterized enzymes. a structural model was generated for hopq1 based on the e. coli rihb nucleoside hydrolase and the role ...201323555744
comparative genomics of multiple strains of pseudomonas cannabina pv. alisalensis, a potential model pathogen of both monocots and dicots.comparative genomics of closely related pathogens that differ in host range can provide insights into mechanisms of host-pathogen interactions and host adaptation. furthermore, sequencing of multiple strains with the same host range reveals information concerning pathogen diversity and the molecular basis of virulence. here we present a comparative analysis of draft genome sequences for four strains of pseudomonas cannabina pathovar alisalensis (pcal), which is pathogenic on a range of monocotyl ...201323555661
pseudomonas syringae pv. actinidiae from recent outbreaks of kiwifruit bacterial canker belong to different clones that originated in china.a recently emerged plant disease, bacterial canker of kiwifruit (actinidia deliciosa and a. chinensis), is caused by pseudomonas syringae pv. actinidiae (psa). the disease was first reported in china and japan in the 1980s. a severe outbreak of psa began in italy in 2008 and has spread to other european countries. psa was found in both new zealand and chile in 2010. to study the evolution of the pathogen and analyse the transmission of psa between countries, genomes of strains from china and jap ...201323555547
pseudomonas syringae pv. syringae uses proteasome inhibitor syringolin a to colonize from wound infection sites.infection of plants by bacterial leaf pathogens at wound sites is common in nature. plants defend wound sites to prevent pathogen invasion, but several pathogens can overcome spatial restriction and enter leaf tissues. the molecular mechanisms used by pathogens to suppress containment at wound infection sites are poorly understood. here, we studied pseudomonas syringae strains causing brown spot on bean and blossom blight on pear. these strains exist as epiphytes that can cause disease upon woun ...201323555272
a circadian clock-regulated toggle switch explains atgrp7 and atgrp8 oscillations in arabidopsis thaliana.the circadian clock controls many physiological processes in higher plants and causes a large fraction of the genome to be expressed with a 24h rhythm. the transcripts encoding the rna-binding proteins atgrp7 (arabidopsis thaliana glycine rich protein 7) and atgrp8 oscillate with evening peaks. the circadian clock components cca1 and lhy negatively affect atgrp7 expression at the level of transcription. atgrp7 and atgrp8, in turn, negatively auto-regulate and reciprocally cross-regulate post-tra ...201323555221
horizontal transfer of a subtilisin gene from plants into an ancestor of the plant pathogenic fungal genus colletotrichum.the genus colletotrichum contains a large number of phytopathogenic fungi that produce enormous economic losses around the world. the effect of horizontal gene transfer (hgt) has not been studied yet in these organisms. inter-kingdom hgt into fungal genomes has been reported in the past but knowledge about the hgt between plants and fungi is particularly limited. we describe a gene in the genome of several species of the genus colletotrichum with a strong resemblance to subtilisins typically fou ...201323554975
catalyzing plant science research with rna-seq.next generation dna sequencing technologies are driving increasingly rapid, affordable and high resolution analyses of plant transcriptomes through sequencing of their associated cdna (complementary dna) populations; an analytical platform commonly referred to as rna-sequencing (rna-seq). since entering the arena of whole genome profiling technologies only a few years ago, rna-seq has proven itself to be a powerful tool with a remarkably diverse range of applications, from detailed studies of bi ...201323554602
a novel l-isoleucine-4'-dioxygenase and l-isoleucine dihydroxylation cascade in pantoea ananatis.a unique operon structure has been identified in the genomes of several plant- and insect-associated bacteria. the distinguishing feature of this operon is the presence of tandem hila and hilb genes encoding dioxygenases belonging to the pf13640 and pf10014 (bsma) pfam families, respectively. the genes encoding hila and hilb from pantoea ananatis aj13355 were cloned and expressed in escherichia coli. the culturing of e. coli cells expressing hila (e. coli-hila) or both hila and hilb (e. coli-hil ...201323554367
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
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
transcriptional profiling of rice early response to magnaporthe oryzae identified oswrkys as important regulators in rice blast resistance.rice blast disease is a major threat to rice production worldwide, but the mechanisms underlying rice resistance to the causal agent magnaporthe oryzae remain elusive. therefore, we carried out a transcriptome study on rice early defense response to m. oryzae. we found that the transcriptional profiles of rice compatible and incompatible interactions with m. oryzae were mostly similar, with genes regulated more prominently in the incompatible interactions. the functional analysis showed that the ...201323544090
zmlea3, a multifunctional group 3 lea protein from maize (zea mays l.), is involved in biotic and abiotic stresses.late embryogenesis abundant (lea) proteins accumulate to high levels during the late stage of seed maturation and in response to water deficit, and are involved in protecting higher plants from damage caused by environmental stresses, especially drought. in the present study, a novel maize (zea mays l.) group 3 lea gene, zmlea3, was identified and later characterized using transgenic tobacco plants to investigate its functions in abiotic and biotic stresses. transcript accumulation demonstrated ...201323543751
posttranslational modification of flagellin flab in shewanella oneidensis.shewanella oneidensis is a highly motile organism by virtue of a polar, glycosylated flagellum composed of flagellins flaa and flab. in this study, the functional flagellin flab was isolated and analyzed with nano-liquid chromatography-mass spectrometry (ms) and tandem ms. in combination with the mutational analysis, we propose that the flab flagellin protein from s. oneidensis is modified at five serine residues with a series of novel o-linked posttranslational modifications (ptms) that differ ...201323543712
bean common bacterial blight: pathogen epiphytic life and effect of irrigation practices.in recent years, bean common bacterial blight (cbb) caused by xanthomonas axonopodis pv. phaseoli (xap) has caused serious yield losses in several countries. cbb is considered mainly a foliar disease in which symptoms initially appear as small water-soaked spots that then enlarge and become necrotic and usually bordered by a chlorotic zone. xap epiphytic population community has a critical role in the development of the disease and subsequent epidemics. the epiphytic population of xap in the fie ...201323539532
molecular signatures in arabidopsis thaliana in response to insect attack and bacterial infection.under the threat of global climatic change and food shortages, it is essential to take the initiative to obtain a comprehensive understanding of common and specific defence mechanisms existing in plant systems for protection against different types of biotic invaders. we have implemented an integrated approach to analyse the overall transcriptomic reprogramming and systems-level defence responses in the model plant species arabidopsis thaliana (a. thaliana henceforth) during insect brevicoryne b ...201323536844
heterotrimeric g protein signalling in the plant kingdom.in animals, heterotrimeric g proteins, comprising α-, β-and γ-subunits, perceive extracellular stimuli through cell surface receptors, and transmit signals to ion channels, enzymes and other effector proteins to affect numerous cellular behaviours. in plants, g proteins have structural similarities to the corresponding molecules in animals but transmit signals by atypical mechanisms and effector proteins to control growth, cell proliferation, defence, stomate movements, channel regulation, sugar ...201323536550
family-specific degenerate primer design: a tool to design consensus degenerated oligonucleotides.designing degenerate pcr primers for templates of unknown nucleotide sequence may be a very difficult task. in this paper, we present a new method to design degenerate primers, implemented in family-specific degenerate primer design (fas-dpd) computer software, for which the starting point is a multiple alignment of related amino acids or nucleotide sequences. to assess their efficiency, four different genome collections were used, covering a wide range of genomic lengths: arenavirus (10 × 10(4) ...201323533783
characterization of aphanizomenon ovalisporum amidinotransferase involved in cylindrospermopsin synthesis.an increasing abundance of aphanizomenon ovalisporum in water bodies from diverse world regions has been reported in the last few years, with the majority of the isolated strains producing the toxin cylindrospermopsin (cyn), leading to a rise in ecological and health risks. the understanding of cyn synthesis is crucial in the control of cyn production. an amidinotransferase (amdt) seems to be the first enzyme involved in the synthesis of cyn. in this study, we have cloned and overexpressed the a ...201323533111
quantitative proteomics of tomato defense against pseudomonas syringae infection.genetic and microarray analyses have provided useful information in the area of plant and pathogen interactions. pseudomonas syringae pv. tomato dc3000 (pst) causes bacterial speck disease in tomato. previous studies have shown that changes in response to pathogen infection at transcript level are variable at different time points. this study provides information not only on proteomic changes between a resistant and a susceptible genotype, but also information on changes between an early and a l ...201323533086
multiple exoribonucleases catalyze maturation of the 3' terminus of 16s ribosomal rna (rrna).processing of ribosomal rna (rrna) precursors is an important component of rna metabolism in all cells. however, in no system have we yet identified all the rnases involved in this process. here, we show that four 3'→5'-exoribonucleases, rnases ii, r, and ph, and polynucleotide phosphorylase (pnpase), participate in maturation of the 3' end of 16s rrna. in their absence, 16s precursor molecules with 33 extra 3'-nt accumulate; however, the presence of any one of the four rnases is sufficient to a ...201323532845
br-signaling kinase1 physically associates with flagellin sensing2 and regulates plant innate immunity in arabidopsis.pathogen-associated molecular pattern (pamp)-trigged immunity (pti) is the first defensive line of plant innate immunity and is mediated by pattern recognition receptors. here, we show that a mutation in br-signaling kinase1 (bsk1), a substrate of the brassinosteroid (br) receptor brassinosteroid insensitive1, suppressed the powdery mildew resistance caused by a mutation in enhanced disease resistance2, which negatively regulates powdery mildew resistance and programmed cell death, in arabidopsi ...201323532072
raba members act in distinct steps of subcellular trafficking of the flagellin sensing2 receptor.cell surface proteins play critical roles in the perception of environmental stimuli at the plasma membrane (pm) and ensuing signal transduction. intracellular localization of such proteins must be strictly regulated, which requires elaborate integration of exocytic and endocytic trafficking pathways. subcellular localization of arabidopsis thaliana flagellin sensing2 (fls2), a receptor that recognizes bacterial flagellin, also depends on membrane trafficking. however, our understanding about th ...201323532067
alternative oxidase: a mitochondrial respiratory pathway to maintain metabolic and signaling homeostasis during abiotic and biotic stress in plants.alternative oxidase (aox) is a non-energy conserving terminal oxidase in the plant mitochondrial electron transport chain. while respiratory carbon oxidation pathways, electron transport, and atp turnover are tightly coupled processes, aox provides a means to relax this coupling, thus providing a degree of metabolic homeostasis to carbon and energy metabolism. beside their role in primary metabolism, plant mitochondria also act as "signaling organelles", able to influence processes such as nucle ...201323531539
combined roles of ethylene and endogenous peptides in regulating plant immunity and growth. 201323530253
purification and characterization of ases protein: a subtilisin secreted by acremonium strictum is a novel plant defense elicitor.in this work, the purification and characterization of an extracellular elicitor protein, designated ases, produced by an avirulent isolate of the strawberry pathogen acremonium strictum, are reported. the defense eliciting activity present in culture filtrates was recovered and purified by ultrafiltration (cutoff, 30 kda), anionic exchange (q-sepharose, ph 7.5), and hydrophobic interaction (phenyl-sepharose) chromatographies. two-dimensional sds-page of the purified active fraction revealed a s ...201323530047
functional analysis of endo-1,4-β-glucanases in response to botrytis cinerea and pseudomonas syringae reveals their involvement in plant-pathogen interactions.plant cell wall modification is a critical component in stress responses. endo-1,4-β-glucanases (egs) take part in cell wall editing processes, e.g. elongation, ripening and abscission. here we studied the infection response of solanum lycopersicum and arabidopsis thaliana with impaired egs. transgenic tomcel1 and tomcel2 tomato antisense plants challenged with pseudomonas syringae showed higher susceptibility, callose priming and increased jasmonic acid pathway marker gene expression. these two ...201323528138
resistance of arabidopsis thaliana to the green peach aphid, myzus persicae, involves camalexin and is regulated by micrornas.· small rnas play important roles in resistance to plant viruses and the complex responses against pathogens and leaf-chewing insects. · we investigated whether small rna pathways are involved in arabidopsis resistance against a phloem-feeding insect, the green peach aphid (myzus persicae). we used a 2-wk fecundity assay to assess aphid performance on arabidopsis rna silencing and defence pathway mutants. quantitative real-time polymerase chain reaction was used to monitor the transcriptional ac ...201323528052
thermo-regulation of genes mediating motility and plant interactions in pseudomonas syringae.pseudomonas syringae is an important phyllosphere colonist that utilizes flagellum-mediated motility both as a means to explore leaf surfaces, as well as to invade into leaf interiors, where it survives as a pathogen. we found that multiple forms of flagellum-mediated motility are thermo-suppressed, including swarming and swimming motility. suppression of swarming motility occurs between 28° and 30 °c, which coincides with the optimal growth temperature of p. syringae. both flic (encoding flagel ...201323527276
escherichia coli nema is an efficient chromate reductase that can be biologically immobilized to provide a cell free system for remediation of hexavalent chromium.hexavalent chromium is a serious and widespread environmental pollutant. although many bacteria have been identified that can transform highly water-soluble and toxic cr(vi) to insoluble and relatively non-toxic cr(iii), bacterial bioremediation of cr(vi) pollution is limited by a number of issues, in particular chromium toxicity to the remediating cells. to address this we sought to develop an immobilized enzymatic system for cr(vi) remediation. to identify novel cr(vi) reductase enzymes we fir ...201323527133
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