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Campestris
Kinds of Campestris Terms modified by Campestris Selected AbstractsCan mechanism inform species' distribution models?ECOLOGY LETTERS, Issue 8 2010Lauren B. Buckley Ecology Letters (2010) 13: 1041,1054 Abstract Two major approaches address the need to predict species distributions in response to environmental changes. Correlative models estimate parameters phenomenologically by relating current distributions to environmental conditions. By contrast, mechanistic models incorporate explicit relationships between environmental conditions and organismal performance, estimated independently of current distributions. Mechanistic approaches include models that translate environmental conditions into biologically relevant metrics (e.g. potential duration of activity), models that capture environmental sensitivities of survivorship and fecundity, and models that use energetics to link environmental conditions and demography. We compared how two correlative and three mechanistic models predicted the ranges of two species: a skipper butterfly (Atalopedes campestris) and a fence lizard (Sceloporus undulatus). Correlative and mechanistic models performed similarly in predicting current distributions, but mechanistic models predicted larger range shifts in response to climate change. Although mechanistic models theoretically should provide more accurate distribution predictions, there is much potential for improving their flexibility and performance. [source] Protective effect of the cruciferous vegetable mustard leaf (Brassica campestris) against in vivo chromosomal damage and oxidative stress induced by ,-radiation and genotoxic chemicalsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2008Ashu B. Tiku Abstract We evaluated the possible protective effect of the popular Indian cruciferous vegetable mustard leaf (Brassica campestris) against chromosomal damage and oxidative stress induced by ,-radiation, cyclophosphamide (CPH) and urethane (URE), in mice. In vivo bone marrow micronucleus test was performed to assess chromosomal damage, and oxidative stress was monitored by estimating the changes in lipid peroxidation and the status of glutathione (GSH) as well as redox cycle antioxidants. Pretreatment with 50,250 mg/kg body wt of mustard leaf extract (MLE) for seven days significantly reduced the frequencies of micronuclei induced by ,-radiation, CPH and URE. The protective effect against chromosomal damage was associated with modulation of lipid peroxidation as well as an increase in GSH and the GSH-dependent enzyme glutathione S -transferase (GST). Mass spectral analysis showed the presence of glucosinolates in MLE used for the pretreatment of mice. These findings indicate that intake of the green leafy cruciferous vegetable mustard leaf can lead to protection against in vivo genotoxicity and oxidative stress. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. [source] Opportunities and constraints in the adaptation of technology for the diagnosis of bacterial plant diseases , experience from Tanzania,EPPO BULLETIN, Issue 3-4 2000R. Black In order to improve diagnostic services and plant quarantine capabilities in Tanzania, the techniques of semi-selective media, the BACTID system, metabolic profiling (Biolog), indirect enzyme-linked immunosorbent assays (ELISA) and polymerase chain reaction (PCR) were assessed for suitability with the existing facilities for the diagnosis and detection of plant-pathogenic bacteria of vegetables. Field-collected samples as well as farmers' own and commercial germplasm were used in studies involving Ralstonia solanacearum, Clavibacter michiganensis subsp. michiganensis and Xanthomonas campestris pv. vesicatoria in Solanaceae and X. c. pv. campestris in Brassicaceae. Each of the techniques was used successfully with one or more of the target pathogens; each had advantages depending on the speed, sensitivity and specificity required, as well as the costs of carrying out the diagnosis. However, constraints emerged relating to the use and disposal of materials such as plastic Petri dishes and toxic substances. The more familiar underlying constraints of high cost and poor availability of consumables and erratic water and electricity supply continued to present problems. These problems will be discussed in relation to the development of an integrated and sustainable approach to the provision of routine diagnostic services. [source] COSTS OF AN INDUCED IMMUNE RESPONSE ON SEXUAL DISPLAY AND LONGEVITY IN FIELD CRICKETSEVOLUTION, Issue 10 2004Alain Jacot Abstract Immune system activation may benefit hosts by generating resistance to parasites. However, natural resources are usually limited, causing a trade-off between the investment in immunity and that in other life-history or sexually selected traits. Despite its importance for the evolution of host defense, state-dependent fitness costs of immunity received little attention under natural conditions. In a field experiment we manipulated the nutritional condition of male field crickets Gryllus campestris and subsequently investigated the effect of an induced immune response through inoculation of bacterial lipopolysaccharides. Immune system activation caused a condition-dependent reduction in body condition, which was proportional to the condition-gain during the preceding food-supplementation period. Independent of nutritional condition, the immune insult induced an enduring reduction in daily calling rate, whereas control-injected males fully regained their baseline level of sexual signaling following a temporary decline. Since daily calling rate affects female mate choice under natural conditions, this suggests a decline in male mating success as a cost of induced immunity. Food supplementation enhanced male life span, whereas the immune insult reduced longevity, independent of nutritional status. Thus, immune system activation ultimately curtails male fitness due to a combined decline in sexual display and life span. Our field study thus indicates a key role for fitness costs of induced immunity in the evolution of host defense. In particular, costs expressed in sexually selected traits might warrant the honest advertisement of male health status, thus representing an important mechanism in parasite-mediated sexual selection. [source] Novel domains of the prokaryotic two-component signal transduction systemsFEMS MICROBIOLOGY LETTERS, Issue 1 2001Michael Y. Galperin Abstract The archetypal two-component signal transduction systems include a sensor histidine kinase and a response regulator, which consists of a receiver CheY-like domain and a DNA-binding domain. Sequence analysis of the sensor kinases and response regulators encoded in complete bacterial and archaeal genomes revealed complex domain architectures for many of them and allowed the identification of several novel conserved domains, such as PAS, GAF, HAMP, GGDEF, EAL, and HD-GYP. All of these domains are widely represented in bacteria, including 19 copies of the GGDEF domain and 17 copies of the EAL domain encoded in the Escherichia coli genome. In contrast, these novel signaling domains are much less abundant in bacterial parasites and in archaea, with none at all found in some archaeal species. This skewed phyletic distribution suggests that the newly discovered complexity of signal transduction systems emerged early in the evolution of bacteria, with subsequent massive loss in parasites and some horizontal dissemination among archaea. Only a few proteins containing these domains have been studied experimentally, and their exact biochemical functions remain obscure; they may include transformations of novel signal molecules, such as the recently identified cyclic diguanylate. Recent experimental data provide the first direct evidence of the participation of these domains in signal transduction pathways, including regulation of virulence genes and extracellular enzyme production in the human pathogens Bordetella pertussis and Borrelia burgdorferi and the plant pathogen Xanthomonas campestris. Gene-neighborhood analysis of these new domains suggests their participation in a variety of processes, from mercury and phage resistance to maintenance of virulence plasmids. It appears that the real picture of the complexity of phosphorelay signal transduction in prokaryotes is only beginning to unfold. [source] Quorum-sensing in Gram-negative bacteriaFEMS MICROBIOLOGY REVIEWS, Issue 4 2001Neil A Whitehead Abstract It has become increasingly and widely recognised that bacteria do not exist as solitary cells, but are colonial organisms that exploit elaborate systems of intercellular communication to facilitate their adaptation to changing environmental conditions. The languages by which bacteria communicate take the form of chemical signals, excreted from the cells, which can elicit profound physiological changes. Many types of signalling molecules, which regulate diverse phenotypes across distant genera, have been described. The most common signalling molecules found in Gram-negative bacteria are N -acyl derivatives of homoserine lactone (acyl HSLs). Modulation of the physiological processes controlled by acyl HSLs (and, indeed, many of the non-acyl HSL-mediated systems) occurs in a cell density- and growth phase-dependent manner. Therefore, the term ,quorum-sensing' has been coined to describe this ability of bacteria to monitor cell density before expressing a phenotype. In this paper, we review the current state of research concerning acyl HSL-mediated quorum-sensing. We also describe two non-acyl HSL-based systems utilised by the phytopathogens Ralstonia solanacearum and Xanthomonas campestris. [source] River corridor plants (Stromtalpflanzen) in Central European lowland: a review of a poorly understood plant distribution patternGLOBAL ECOLOGY, Issue 5 2001Michael Burkart Abstract Aim and location In Central European lowlands certain plant species grow mainly or exclusively in the corridors of large rivers. In German-speaking plant geography, they are known as ,Stromtalpflanzen'. The aim of this paper is to review the literature about definitions, explanations and species characteristics and to suggest future directions in research concerning this species group. Results A preliminary list contains 129 ecologically heterogeneous plant species. The mechanisms generating the peculiar distribution pattern may include hydrochory along river corridors, high levels of disturbance by water, variable water availability including inundation and summer drought, warm summers and high nutrient supply on alluvial soils. There is evidence from observational studies for all above mechanisms. However, none of them has been tested experimentally. Demographic data of river corridor plants are limited to very few species, including mainly invasive annuals (Artemisia annua, Bidens frondosa, Cuscuta campestris, Xanthium albinum) and annual (hemi)parasites (Cuscuta campestris, Melampyrum cristatum). Metapopulation studies do not exist to date for European species. Apart from their habitat requirements, river corridor plants were grouped according to their similarities in overall distribution pattern or their distribution within particular river corridors. Main conclusions River corridor plants include a high proportion of threatened plant species. In order to preserve them, and in order to understand the mechanisms generating the peculiar distribution pattern, much more has to be known about their population biology and metapopulation dynamics. [source] Isolation and Characterization of a Porin-Like Outer Membrane Protein from Xanthomonas campestris pv. campestrisIUBMB LIFE, Issue 1 2002Lingyun Wang Abstract Xanthomonas campestris pv. campestris, a plant-associated pathogenic bacterium, is the causal agent of foliar spots and blights in crucifers. The major outer membrane protein, Omp37, of 37 kDa, has been identified, purified to homogeneity, and its characterization has also been carried out. Native Omp37 behaved as a trimer, as revealed by gel filtration and SDS-PAGE. FTIR measurements revealed a high ,-structure content. The pore-forming ability of the purified Omp37 was studied by the liposome swelling assay. Omp37, to our knowledge, is the first porin that has been isolated from Xanthomonas . This study clearly demonstrates that Omp37 is related to the family of trimeric bacterial porins. [source] Evidence for dose-dependent effects on plant growth by Stenotrophomonas strains from different originsJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2003I. Suckstorff Abstract Aims: To assess the influence of Stenotrophomonas on plants, the interaction of 16 Stenotrophomonas strains from clinical and environmental sources with strawberry plant seedlings was analysed. Methods and Results:In vitro, all Stenotrophomonas strains influenced plant growth when applied to seedlings. Whereas most of the Stenotrophomonas strains promoted root growth and hair development, a statistically significantly negative influence on the length of stem was found. Although strains from a clinical origin also showed statistically significant effects on plants, this was generally lower when compared with environmental strains. For three selected strains, a strong dose-dependent effect was observed for all parameters. In vitro, a correlation was found between plant growth promotion and production of a plant growth hormone, indole-3-acetic acid (IAA). Xanthomonas campestris, a phylogenetically very closely related species to Stenotrophomonas, was used as a phytopathogenic control. It too confirmed the reduction of plant growth in this in vitro system. Conclusions: Independent of their origin, Stenotrophomonas strains can produce IAA in vitro and subsequently, influence plant growth. The effect of Stenotrophomonas presence on plants was dose-dependent. Significance and Impact of the Study: The dose-dependent effect of Stenotrophomonas, a bacterium of both biotechnological and medical interest, is of great interest for biocontrol applications of plant-associated strains. This paper is the first report that clearly demonstrates the phytopathogenic capacity of Stenotrophomonas. [source] Maintaining diversity through intermediate disturbances: evidence from rodents colonizing rehabilitating coastal dunesAFRICAN JOURNAL OF ECOLOGY, Issue 4 2000S. M. Ferreira Abstract Rodents inhabit the coastal dune forests of KwaZulu-Natal, South Africa. Here habitat rehabilitation following mining of dunes has resulted in coastal dune forest succession similar to that recorded in nonmined forests. We investigated the colonization of rehabilitating stands and evaluate the role of disturbance in maintaining rodent diversity. A trapping programme was established between July 1993 and February 1995 during which rodent colonization, local extinction and species richness were recorded for rehabilitating stands of different ages. Trends in these variables were closely associated with one of three possible outcomes for a disturbed patch over time, with no intervening disturbances following the initial disturbance. Colonization was initially high which led to an increase in species richness. Extinction was lower than colonization, but became higher when the habitat was 3 years old, which led to a decline in richness. We extrapolate this result assuming negligibly small disturbances after the initiation of rehabilitation and suggest that intermediate levels of disturbance maintain rodent species richness in coastal dune forests. Furthermore, our results illustrated species turnover, a prediction of the recorded outcome, with young stands dominated by Mastomys natalensis and older stands by Saccostomus campestris or Aethomys chrysophilus. Résumé Il y a des rongeurs dans les forêts des dunes côtières du KwaZulu-Natal, en Afrique du Sud. Là, la réhabilitation de l'habitat après l'exploitation minière des dunes a abouti à une succession de forêts côtières des dunes semblable à celle qui est observée dans les forêts non exploitées. Nous avons étudié la colonisation des endroits en voie de réhabilitation et évalué le rôle des perturbations dans le maintien de la diversité des rongeurs. On a mis au point un programme de piégeage entre juillet 1993 et février 1995, pendant lequel on a noté la colonisation par les rongeurs, l'extinction locale et la richesse en espèces pour les endroits à différents stades de réhabilitation. Les tendances pour ces variables étaient étroitement associées à l'un des trois résultats possibles que peut conna,^tre avec le temps un endroit qui a été perturbé, lorsque aucune autre perturbation ne suit la première. La colonisation a d'abord été forte, ce qui a causé un enrichissement des espèces. Les extinctions étaient moins fréquentes que les colonisations, mais elles ont augmenté lorsque le nouvel habitat a atteint l'âge de trois ans, ce qui a entra,^né une perte de richesse en espèces. Nous extrapolons ce résultant en supposant que ce sont de petites perturbations négligeables après le démarrage de la réhabilitation et nous suggérons que des taux moyens de perturbation maintiennent la richesse spécifique des rongeurs dans les forêts des dunes côtières. De plus, nos résultats illustrent une rotation des espèces, une prédiction des résultats rapportés, avec les endroits les plus jeunes dominés par Mastomys natalensis et les plus anciens par Saccostomus campestris et Aethomys chrysophilus. [source] Demographic variation and population viability in Gentianella campestris: effects of grassland management and environmental stochasticityJOURNAL OF ECOLOGY, Issue 3 2001Tommy Lennartsson Summary 1,Transition matrix models were used to evaluate the effects of environmental stochasticity and four different methods of grassland management on dynamics and viability of a population of the biennial Gentianella campestris (Gentianaceae) in species-rich grassland. Data were collected between 1990 and 1995. 2,Continuous summer grazing, the prevailing management strategy in Scandinavian grasslands, resulted in high recruitment of new plants, mainly because litter accumulation was prevented and gaps were created by trampling. Trampling and repeated grazing, however, caused damage which reduced seed production. Lambda for the average matrix was c. 0.77, and a stochastic matrix model yielded an extinction probability for the total population of c. 0.08 within 50 years. 3,Mowing in mid-July (used as a conservation tool) increased seed production, but litter accumulation following re-growth of the vegetation prevented establishment. Lambda and extinction risk were similar to continuous grazing. 4,Mowing in October (another conservation tool) promoted recruitment because of low litter accumulation, but the seed output decreased because plant growth was impaired by tall vegetation. Lambda was 0.64, while the extinction probability was very high (c. 0.98 within 50 years). 5,Mid-July mowing followed by autumn grazing (the historical management regime) yielded high values for both seed production and establishment of rosettes. Lambda was 0.94 and the probability of extinction within 50 years was below detection level. 6,Log-linear analysis showed that the matrices differed significantly both between treatments and between years. The latter indicates environmental stochasticity, here caused by summer drought that increased the extinction risk. Lambda may be slightly underestimated because drought occurred in one out of five summers during the study period, which is high compared with the natural frequency. 7,We conclude that traditional grassland management is more favourable for G. campestris than the methods that prevail in Scandinavia today. This indicates a serious conservation problem, because grazing has replaced traditional management in many of the remaining semi-natural grasslands throughout Europe. [source] ALKALOID COMPOSITION OF LUPINUS CAMPESTRIS FROM MEXICOJOURNAL OF FOOD BIOCHEMISTRY, Issue 2 2001J. MARTÍNEZ-HERRERA ABSTRACT The content of quinolizidine alkaloids (QA) in Lupinus campestris, Fabaceae family, was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS), Samples of various organs of Lupinus campestris collected at different monthly stages of the growing plant, were subjected to extraction in a Merck Extrelut column. The quinolizidine alkaloid patterns of stems, leaves, flowers, pods and seeds were assessed and then identified and quantified by GC. Alkaloid structures were identified according to their mass fragmentation patterns, in combination with their indicative Kovats retention index. Alkaloids found in several developmental stages of the plant were mainly: aphyllidine, 5, 6-dehydrolupanine, aphylline, dehydro-oxosparteine, lupanine, ,-isolupanine, hydroxyaphylline and hydroxyaphyllidine, plus two alkaloids that -were not identified. During the third month the relative abundance of total alkaloids were highest. The main alkaloids found in seeds were hydroxyaphylline and hydroxyaphyllidine. [source] A new method for the synthesis and herbicidal activity of 3-phenoxy-6-(1H- (substituted)pyrazol-1-yl) pyridazinesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2009Fang-Zhong Hu A series of 3-substituted phenoxy-6-((substituted)1H -pyrazol-1-yl) pyridazines were synthesized from the condensation of various phenols and 3-chloro-6-(1H -pyrazol-1-yl) pyridazine 2 or 3-chloro-6-(5,-methyl-4-ethoxycarbonyl- 1H -pyrazol-1-yl) pyridazine 6 in N,N-dimethylformamide (DMF) at 120°C with K2CO3 as an acid receptor. The intermediates 2 or 6 were obtained from the cyclization of 3-chloro-6-hydrazinyl pyridazine 1 with 3-dimethylamino-acrylaldehyde or ethyl 2-((dimethylamino) methylene)-3-oxobutanoate in n -butanol under reflux, respectively, and side products 3 or 7 were also generated. All of the title compounds were confirmed by 1H NMR, infrared spectometry (IR) and elemental analyses. Preliminary bioassay indicated that some of the title compounds showed high inhibitory activity against Brassica campestris L. (B. campestris) and moderate inhibitory activity against Echinochloa crusgalli. For example, the inhibition percentages of compound 4b and 4c against B. campestris were both 94% at 10 ,g/mL. J. Heterocyclic Chem., (2009). [source] Lipid transfer proteins from Brassica campestris and mung bean surpass mung bean chitinase in exploitabilityJOURNAL OF PEPTIDE SCIENCE, Issue 10 2007Peng Lin Abstract Antifungal peptides with a molecular mass of 9 kDa and an N -terminal sequence demonstrating remarkable similarity to those of nonspecific lipid transfer proteins (nsLTPs) were isolated from seeds of the vegetable Brassica campestris and the mung bean. The purified peptides exerted an inhibitory action on mycelial growth in various fungal species. The antifungal activity of Brassica and mung bean nsLTPs were thermostable, pH-stable, and stable after treatment with pepsin and trypsin. In contrast, the antifungal activity of mung bean chitinase was much less stable to changes in pH and temperature. Brassica LTP inhibited proliferation of hepatoma Hep G2 cells and breast cancer MCF 7 cells with an IC50 of 5.8 and 1.6 µM, respectively, and the activity of HIV-1 reverse transcriptase with an IC50 of 4 µM. However, mung bean LTP and chitinase were devoid of antiproliferative and HIV-1 reverse transcriptase inhibitory activities. In contrast to the mung bean LTP, which exhibited antibacterial activity, Brassica LTP was inactive. All three antifungal peptides lacked mitogenic activity toward splenocytes. These results indicate that the two LTPs have more desirable activities than the chitinase and that there is a dissociation between the antifungal and other activities of these antifungal proteins. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] RHEOLOGICAL AND PHYSICAL PROPERTIES OF DATE JUICE PALM BY-PRODUCT (PHOENIX DACTYLIFERA L.) AND COMMERCIAL XANTHAN GUMSJOURNAL OF TEXTURE STUDIES, Issue 2 2010RIADH BEN SALAH ABSTRACT Rheological and thermal properties of xanthan produced by Xanthomonas campestris from date by-products (DBP-xanthan) and commercial xanthan were determined. DBP-xanthan gave solutions with lower apparent viscosity than commercial xanthan. However, DBP-xanthan solutions were more stable to temperature changes and ionic strength than commercial xanthan. Gradual increase of storage modulus (G,) as function of frequency was observed for the two polysaccharides. On the other hand, loss modulus (G,) remained constant for DBP-xanthan and an increase was observed for commercial xanthan. Granulometric profile indicates that DPB-xanthan particle size was lower than commercial xanthan. Differential scanning calorimetry showed that the melting temperatures (Tm) and enthalpy (,Hm) of DBP-xanthan were higher than those of commercial xanthan. These properties of DBP-xanthan are quite rare among xanthan described in the literature and give this new gum great potential for use in the field of bioindustries as thickening and stabilizing agents. PRACTICAL APPLICATIONS Xanthan gum from date by-products (DBP-xanthan) was recently produced in our laboratory. No work has been undertaken to study the rheological properties of this polysaccharide to date. Rheological and some physicals properties were compared to those of commercial xanthan. This could promote industrial use of DBPs as low-cost natural source for xanthan gum production. [source] Characterization of microsatellite markers for rough fescue species (Festuca spp.)MOLECULAR ECOLOGY RESOURCES, Issue 3 2006YONG-BI FU Abstract One major challenge in genetic diversity analysis of minor grass species is the lack of informative molecular markers. A set of 210 simple sequence repeat (SSR) markers developed from wheat and barley were evaluated for their transferability to three rough fescue species [Festuca altaica Trinius, F. campestris (Rydb.) and F. hallii (Vassey) Piper]. Twelve SSR primer pairs displayed scorable polymorphism among and within the species. The number of alleles per primer pair ranged from three to 17 with an average of 8.3 for all the species and greatly varied for each species. About 82% of SSR variation resided within the species. Festuca hallii was genetically most distinct among the three species. [source] Co-regulation of Xanthomonas campestris virulence by quorum sensing and a novel two-component regulatory system RavS/RavRMOLECULAR MICROBIOLOGY, Issue 6 2009Ya-Wen He Summary Xanthomonas campestris pv. campestris (Xcc) is known to regulate virulence through a quorum-sensing mechanism. Detection of the quorum-sensing signal DSF by sensor RpfC leads to activation of the response regulator RpfG, which influences virulence by degrading cyclic-di-GMP and by subsequent increasing expression of the global regulator Clp. In this study, we show that mutation of a response regulator RavR containing the GGDEF,EAL domains decreases Xcc virulence factor production. The functionality of RavR is dependent on its EAL domain-associated cyclic-di-GMP phosphodiesterase activity. Deletion of a multidomain sensor gene ravS, which shares the same operon with ravR, results in similar phenotype changes as the ravR mutant. In addition, the sensor mutant phenotypes can be rescued by in trans expression of the response regulator, supporting the notion that RavS and RavR constitute a two-component regulatory system. Significantly, mutation of either the PAS domain or key residues of RavS implicated in sensing low-oxygen tension abrogates the sensor activity in virulence regulation. Moreover, similar to the DSF signalling system, RavS/RavR regulates virulence gene expression through the global regulator Clp. These results outline a co-regulation mechanism that allows Xcc to integrate population density and environmental cues to modulate virulence factor production and adaptation. [source] Over-expression of putative transcriptional coactivator KELP interferes with Tomato mosaic virus cell-to-cell movementMOLECULAR PLANT PATHOLOGY, Issue 2 2009NOBUMITSU SASAKI SUMMARY Tomato mosaic virus (ToMV) encodes a movement protein (MP) that is necessary for virus cell-to-cell movement. We have demonstrated previously that KELP, a putative transcriptional coactivator of Arabidopsis thaliana, and its orthologue from Brassica campestris can bind to ToMV MP in vitro. In this study, we examined the effects of the transient over-expression of KELP on ToMV infection and the intracellular localization of MP in Nicotiana benthamiana, an experimental host of the virus. In co-bombardment experiments, the over-expression of KELP inhibited virus cell-to-cell movement. The N-terminal half of KELP (KELPdC), which had been shown to bind to MP, was sufficient for inhibition. Furthermore, the over-expression of KELP and KELPdC, both of which were co-localized with ToMV MP, led to a reduction in the plasmodesmal association of MP. In the absence of MP expression, KELP was localized in the nucleus and the cytoplasm by the localization signal in its N-terminal half. It was also shown that ToMV amplified normally in protoplasts prepared from leaf tissue that expressed KELP transiently. These results indicate that over-expressed KELP interacts with MP in vivo and exerts an inhibitory effect on MP function for virus cell-to-cell movement, but not on virus amplification in individual cells. [source] Optimization of pathogenicity assays to study the Arabidopsis thaliana,Xanthomonas campestris pv. campestris pathosystemMOLECULAR PLANT PATHOLOGY, Issue 3 2005DAMIEN MEYER SUMMARY The cruciferous weed Arabidopsis thaliana and the causal agent of black rot disease of Crucifers Xanthomonas campestris pv. campestris (Xcc) are both model organisms in plant pathology. Their interaction has been studied successfully in the past, but these investigations suffered from high variability. In the present study, we describe an improved Arabidopsis,Xcc pathosystem that is based on a wound inoculation procedure. We show that after wound inoculation, Xcc colonizes the vascular system of Arabidopsis leaves and causes typical black rot symptoms in a compatible interaction, while in an incompatible interaction bacterial multiplication is inhibited. The highly synchronous and reproducible symptom expression allowed the development of a disease scoring scheme that enabled us to analyse the effects of mutations in individual genes on plant resistance or on bacterial virulence in a simple and precise manner. This optimized Arabidopsis,Xcc pathosystem will be a robust tool for further genetic and post-genomic investigation of fundamental questions in plant pathology. [source] Xanthomonas citri: breaking the surfaceMOLECULAR PLANT PATHOLOGY, Issue 3 2003Asha M. Brunings SUMMARY Taxonomy: Bacteria; Proteobacteria, Gammaproteobacteria; Xanthomonadales; Xanthomonadaceae, Xanthomonas. Microbiological properties: Gram-negative, obligately aerobic, straight rods, motile by a single polar flagellum, yellow pigment. Related species:X. campestris , X. axonopodis , X. oryzae , X. albilineans . Host range: Affects Rutaceous plants, primarily Citrus spp., Fortunella spp., and Poncirus spp., world-wide. Quarantined pathogen in many countries. Economically important hosts are cultivated orange, grapefruit, lime, lemon, pomelo and citrus rootstock. Disease symptoms: On leaves, first appearance is as oily looking, 2,10 mm, similarly sized, circular spots, usually on the abaxial surface. On leaves, stems, thorns and fruit, circular lesions become raised and blister-like, growing into white or yellow spongy pustules. These pustules then darken and thicken into a light tan to brown corky canker, which is rough to the touch. On stems, pustules may coalesce to split the epidermis along the stem length, and occasionally girdling of young stems may occur. Older lesions on leaves and fruit tend to have more elevated margins and are at times surrounded by a yellow chlorotic halo (that may disappear) and a sunken centre. Sunken craters are especially noticeable on fruit, but the lesions do not penetrate far into the rind. Defoliation and premature abscission of affected fruit occurs on heavily infected trees. Useful websites: Are herbicide-resistant crops the answer to controlling Cuscuta?PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 7 2009Talia Nadler-Hassar Abstract BACKGROUND: Herbicide-resistant crop technology could provide new management strategies for the control of parasitic plants. Three herbicide-resistant oilseed rape (Brassica napus L.) genotypes were used to examine the response of attached Cuscuta campestris Yuncker to glyphosate, imazamox and glufosinate. Cuscata campestris was allowed to establish on all oilseed rape genotypes before herbicides were applied. RESULTS: Unattached seedlings of C. campestris, C. subinclusa Durand & Hilg. and C. gronovii Willd. were resistant to imazamox and glyphosate and sensitive to glufosinate, indicating that resistance initially discovered in C. campestris is universal to all Cuscuta species. Glufosinate applied to C. campestris attached to glufosinate-resistant oilseed rape had little impact on the parasite, while imazamox completely inhibited C. campestris growth on the imidazolinone-resistant host. The growth of C. campestris on glyphosate-resistant host was initially inhibited by glyphosate, but the parasite recovered and resumed growth within 3,4 weeks. CONCLUSION: The ability of C. campestris to recover was related to the quality of interaction between the host and parasite and to the resistance mechanism of the host. The parasite was less likely to recover when it had low compatibility with the host, indicating that parasite-resistant crops coupled with herbicide resistance could be highly effective in controlling Cuscuta. Published 2009 by John Wiley & Sons, Ltd. [source] A steroid fraction of chloroform extract from bee pollen of Brassica campestris induces apoptosis in human prostate cancer PC-3 cellsPHYTOTHERAPY RESEARCH, Issue 11 2007Yao-Dong Wu Abstract Bee pollen of Brassica campestris L. is widely used in China as a natural food supplement and an herbal medicine in strengthening the body's resistance against diseases including cancer. The present study was carried out to investigate the effect of a steroid fraction of chloroform extract from bee pollen of Brassica campestris L. on human cancer cell viability. Our studies show that among nine cancer cell lines of different origin (PC-3, LNCaP, MCF-7, Hela, BEL-7402, BCG-823, KB, A549 and HO8910), this steroid fraction displayed the strongest cytotoxicity in human prostate cancer PC-3 cells. The mode of cell death appeared to be apoptosis in PC-3 cells, as shown by flow-cytometric analysis and fluorescence microscopes. Caspase-3 activity was obviously enhanced after the cells were treated with the fraction. A time-dependent decrease in the expression of anti-apoptotic protein Bcl-2 was also observed by Western blot analysis. It is suggested that the steroid fraction could induce cytotoxicity in prostate cancer PC-3 cells by triggering apoptosis. The studies indicate that the steroid fraction of chloroform extract from bee pollen of Brassica campestris L. may be a promising candidate for the treatment of advanced prostate cancer. Copyright © 2007 John Wiley & Sons, Ltd. [source] Backcross breeding for improved resistance to common bacterial blight in pinto bean (Phaseolus vulgaris L.)PLANT BREEDING, Issue 3 2005N. Mutlu Abstract Common bacterial blight (CBB) caused by Xanthomonas campestris pv. phaseoli reduces common bean (Phaseolus vulgaris L.) yield and quality worldwide. Genetic resistance provides effective disease control; however. a high level of resistance is difficult to attain and does not exist in pinto bean, the most important dry bean market class in North America. Our objective was to determine if a backcross breeding approach with the aid of molecular markers linked to quantitative trait loci (QTL) for resistance to CBB in a donor parent could be used to attain higher levels of resistance to CBB in pinto bean. QTL conditioning CBB resistance from the donor parent XAN 159 were introgressed into the recurrent parent,Chase'using classical backcross breeding and intermittent marker-assisted selection.,Chase'pinto bean is moderately resistant and the breeding line XAN 159 is highly resistant to Xanthomonas campestris. Marker assays confirmed the presence of independent QTL from GN no. 1 Sel 27 and XAN 159 in advanced backcross-derived pinto bean lines with improved CBB resistance. Agronomic characteristics of,Chase'were fully recovered in the backcross-derived lines. An important QTL for CBB resistance from XAN 159 on linkage group B6 was not introgressed because tight linkage between this QTL and the dominant V allele that causes an unacceptable black-mottled seed coat colour pattern in pinto bean could not be broken. [source] Molecular characterization of novel resynthesized rapeseed (Brassica napus) lines and analysis of their genetic diversity in comparison with spring rapeseed cultivars,PLANT BREEDING, Issue 6 2003F. Seyis Abstract Resynthesized (RS) rapeseed generated from interspecific hybridization between suitable forms of Brassica rapa L. (syn. campestris; genome AA, 2n = 20) and B. oleracea L. (CC, 2n = 18) represents a potentially important resource to expand genetic diversity in the narrow gene pool of oilseed rape (B. napus L., AACC, 2n = 38). In this study 165 RS rapeseed lines originating from crosses between an Indian Yellow Sarson (B. rapa ssp. trilocularis) and five different cauliflower (B. oleracea convar. botrytis) cultivars were studied using amplified fragment length polymorphism (AFLP) markers and their genetic diversity was compared in relationship to an assortment of 40 diverse spring oilseed and fodder rape varieties. Using three AFLP primer combinations, a total of 467 polymorphic bands were scored. Cluster analysis allowed differentiation among the different RS lines, which, as expected, were genetically highly divergent from the cultivars. The genetic diversity of the material is discussed in relation to its morphological variability with a view to the implementation of RS lines in oilseed rape breeding. [source] Bacterial leaf blight of strawberry (Fragaria (x) ananassa) caused by a pathovar of Xanthomonas arboricola, not similar to Xanthomonas fragariae Kennedy & King.PLANT PATHOLOGY, Issue 6 2001Description of the causal organism as Xanthomonas arboricola pv. fragariae (pv. nov., comb. nov.) A new bacterial disease of strawberry is described. This disease, called bacterial leaf blight of strawberry, is characterized by dry, brown necrotic leaf spots and large brown V-shaped lesions along the leaf margin, midrib and major veins. Symptoms are different from angular leaf spot of strawberry caused by the bacterium Xanthomonas fragariae. Strains of the bacterial leaf blight pathogen were characterized in a polyphasic approach by biochemical tests, fatty acid analysis, protein electrophoresis, serology, PCR, pigment analysis, ice-nucleation activity, AFLP analysis, DNA:DNA hybridization, pathogenicity and host range tests, and compared with a number of reference strains of X. fragariae and other Xanthomonas species. Bacterial leaf blight strains formed a homogeneous group in all tests, completely different from X. fragariae. They were the only strains causing leaf blight of strawberry upon artificial inoculation into strawberry. Fatty acid and protein electrophoretic analysis showed that the strains belong to the phenon X. campestris (sensu latu, including pathovars now classified as belonging to X. arboricola). AFLP analysis and DNA:DNA hybridization further clarified their taxonomic position as belonging to X. arboricola. The name X. arboricola pv. fragariae is proposed for the bacterium causing leaf blight of strawberry with strain PD2780 (LMG 19145) as pathovar type strain. Criteria for routine identification are given and the taxonomic status is discussed. [source] The redox switch of ,-glutamylcysteine ligase via a reversible monomer,dimer transition is a mechanism unique to plantsTHE PLANT JOURNAL, Issue 6 2008Roland Gromes Summary In plants, the first committed enzyme for glutathione biosynthesis, ,-glutamylcysteine ligase (GCL), is under multiple controls. The recent elucidation of GCL structure from Brassica juncea (BjGCL) has revealed the presence of two intramolecular disulfide bridges (CC1, CC2), which both strongly impact on GCL activity in vitro. Here we demonstrate that cysteines of CC1 are confined to plant species from the Rosids clade, and are absent in other plant families. Conversely, cysteines of CC2 involved in the monomer,dimer transition in BjGCL are not only conserved in the plant kingdom, but are also conserved in the evolutionarily related ,- (and some ,-) proteobacterial GCLs. Focusing on the role of CC2 for GCL redox regulation, we have extended our analysis to all available plant (31; including moss and algal) and related proteobacterial GCL (46) protein sequences. Amino acids contributing to the homodimer interface in BjGCL are highly conserved among plant GCLs, but are not conserved in related proteobacterial GCLs. To probe the significance of this distinction, recombinant GCLs from Nicotiana tabacum (NtGCL), Agrobacterium tumefaciens (AtuGCL, ,-proteobacteria) and Xanthomonas campestris (XcaGCL, ,-proteobacteria) were analyzed for their redox response. As expected, NtGCL forms a homodimer under oxidizing conditions, and is activated more than threefold. Conversely, proteobacterial GCLs remain monomeric under oxidizing and reducing conditions, and their activities are not inhibited by DTT, despite the presence of CC2. We conclude that although plant GCLs are evolutionarily related to proteobacterial GCLs, redox regulation of their GCLs via CC2-dependent dimerization has been acquired later in evolution, possibly as a consequence of compartmentation in the redox-modulated plastid environment. [source] The conserved Xanthomonas campestris pv. vesicatoria effector protein XopX is a virulence factor and suppresses host defense in Nicotiana benthamianaTHE PLANT JOURNAL, Issue 6 2005Matthew Metz Summary Nicotiana benthamiana leaves display a visible plant cell death response when infiltrated with a high titer inoculum of the non-host pathogen, Xanthomonas campestris pv. vesicatoria (Xcv). This visual phenotype was used to identify overlapping cosmid clones from a genomic cosmid library constructed from the Xcv strain, GM98-38. Individual cosmid clones from the Xcv library were conjugated into X. campestris pv. campestris (Xcc) and exconjugants were scored for an altered visual high titer inoculation response in N. benthamiana. The molecular characterization of the cosmid clones revealed that they contained a novel gene, xopX, that encodes a 74-kDa type III secretion system (TTSS) effector protein. Agrobacterium -mediated transient expression of XopX in N. benthamiana did not elicit the plant cell death response although detectable XopX protein was produced. Interestingly, the plant cell death response occurred when the xopX Agrobacterium -mediated transient expression construct was co-inoculated with strains of either Xcv,xopX or Xcc, both lacking xopX. The co-inoculation complementation of the plant cell death response also depends on whether the Xanthomonas strains contain an active TTSS. Transgenic 35S- xopX -expressing N. benthamiana plants also have the visible plant cell death response when inoculated with the non- xopX -expressing strains Xcv,xopX and Xcc. Unexpectedly, transgenic 35S- xopX N. benthamiana plants displayed enhanced susceptibility to bacterial growth of Xcc as well as other non- xopX -expressing Xanthomonas and Pseudomonas strains. This result is also consistent with the increase in bacterial growth on wild type N. benthamiana plants observed for Xcc when XopX is expressed in trans. Furthermore, XopX contributes to the virulence of Xcv on host pepper (Capsicum annuum) and tomato (Lycopersicum esculentum) plants. We propose that the XopX bacterial effector protein targets basic innate immunity in plants, resulting in enhanced plant disease susceptibility. [source] The apo structure of sucrose hydrolase from Xanthomonas campestris pv. campestris shows an open active-site grooveACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2009Elise Champion Glycoside hydrolase family 13 (GH-13) mainly contains starch-degrading or starch-modifying enzymes. Sucrose hydrolases utilize sucrose instead of amylose as the primary glucosyl donor. Here, the catalytic properties and X-ray structure of sucrose hydrolase from Xanthomonas campestris pv. campestris are reported. Sucrose hydrolysis catalyzed by the enzyme follows Michaelis,Menten kinetics, with a Km of 60.7,mM and a kcat of 21.7,s,1. The structure of the enzyme was solved at a resolution of 1.9,Å in the resting state with an empty active site. This represents the first apo structure from subfamily 4 of GH-13. Comparisons with structures of the highly similar sucrose hydrolase from X. axonopodis pv. glycines most notably showed that residues Arg516 and Asp138, which form a salt bridge in the X. axonopodis sucrose complex and define part of the subsite ,1 glucosyl-binding determinants, are not engaged in salt-bridge formation in the resting X. campestris enzyme. In the absence of the salt bridge an opening is created which gives access to subsite ,1 from the `nonreducing' end. Binding of the glucosyl moiety in subsite ,1 is therefore likely to induce changes in the conformation of the active-site cleft of the X. campestris enzyme. These changes lead to salt-bridge formation that shortens the groove. Additionally, this finding has implications for understanding the molecular mechanism of the closely related subfamily 4 glucosyl transferase amylosucrase, as it indicates that sucrose could enter the active site from the `nonreducing' end during the glucan-elongation cycle. [source] Crystallization and preliminary X-ray diffraction characterization of an essential protein from Xanthomonas campestris that contains a noncanonical PilZ signature motif yet is critical for pathogenicityACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 10 2009Tso-Ning Li Recent studies have identified c-di-GMP as a novel secondary messenger molecule that is heavily involved in regulating bacterial biofilm formation, motility, production of pathogenicity factors etc. PilZ domain-containing proteins have been suggested and subsequently proved to be the c-di-GMP receptor. However, considering the diverse biological functions exhibited by c-di-GMP, it may be that receptors other than the PilZ domain exist. An essential protein from the plant pathogen Xanthomonas campestris pv. campestris (Xcc) that contains a noncanonical PilZ signature motif yet is critical for Xcc pathogenicity has been cloned, purified and crystallized. Detailed characterization of this protein may reveal an alternative binding mode of c-di-GMP and allow a more thorough understanding of how c-di-GMP exhibits its diverse effects. [source] Surface display of transglucosidase on Escherichia coli by using the ice nucleation protein of Xanthomonas campestris and its application in glucosylation of hydroquinoneBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2006Po-Hung Wu Abstract A surface anchoring motif using the ice nucleation protein (INP) of Xanthomonas campestris pv. campestris BCRC 12846 for display of transglucosidase has been developed. The transglucosidase gene from Xanthomonas campestris pv. campestris BCRC 12608 was fused to the truncated ina gene. This truncated INP consisting of N- and C-terminal domains (INPNC) was able to direct the expressed transglucosidase fusion protein to the cell surface of E. coli with apparent high enzymatic activity. The localization of the truncated INPNC-transglucosidase fusion protein was examined by Western blot analysis and immunofluorescence labeling, and by whole-cell enzyme activity in the glucosylation of hydroquinone. The glucosylation reaction was carried out at 40°C for 1 h, which gave 23 g/L of ,-arbutin, and the molar conversion based on the amount of hydroquinone reached 83%. The use of whole-cells of the wild type strain resulted in an ,-arbutin concentration of 4 g/L and a molar conversion of 16% only under the same conditions. The results suggested that E. coli displaying transglucosidase using truncated INPNC as an anchoring motif can be employed as a whole-cell biocatalyst in glucosylation. © 2006 Wiley Periodicals, Inc. [source]
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