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Systemic Resistance (systemic + resistance)
Kinds of Systemic Resistance Selected AbstractsEffects of phlebotomy on haemodynamic characteristics during exercise in Standardbred trotters with red cell hypervolaemiaEQUINE VETERINARY JOURNAL, Issue 4 2001P. FUNKQUIST Summary Five Standardbred trotters with red cell hypervolaemia (RCHV) were compared before and after removal of approximately 22% (36 ml/kg bwt) of the total blood volume in order to evaluate the haemodynamic responses, haemorheological alterations and oxygen transport during exercise to fatigue. Data were recorded during submaximal exercise at 4 different speeds on a treadmill and then during continued running at the highest speed step until fatigue. Oxygen uptake (V,O2), pulmonary artery pressure (PAP), systemic artery pressure (SAP), heart rate (HR), haematocrit and haemoglobin concentrations (Hb) were measured. Arteriovenous O2 content difference (C(a-v,)O2), pulmonary vascular resistance (PVR) and total systemic resistance (TSR) were calculated. Whole blood and plasma viscosity and erythrocyte aggregation tendency were determined with a rotational viscometer. Endoscopy was performed after exercise. ANOVA was used for statistical analysis. Phlebotomy resulted in a decrease in haematocrit and Hb during the course of exercise. Blood and plasma viscosity were lower and erythrocyte aggregation tendency was higher after phlebotomy. Throughout exercise, including submaximal work and continued running to fatigue, PAP, SAP, PVR, TSR and C(a-v,)O2 were lower after phlebotomy. HR was higher after phlebotomy during submaximal exercise. Oxygen delivery and VO2 were lower after phlebotomy in the period from submaximal exercise to fatigue. Run time to fatigue was shorter after phlebotomy. Four horses showed exercise-induced pulmonary haemorrhage (EIPH) before phlebotomy and the degree of bleeding was diminished but not abolished after phlebotomy. The reductions in PVR, TSR, PAP and SAP after phlebotomy were probably a result of reduced blood viscosity. In conclusion, although a 22% reduction in blood volume improved the haemodynamic and haemorheological parameters and the degree of EIPH, it was found that RCHV trotters have to rely on high oxygen delivery to the working muscles for maintenance of maximal performance. [source] Bacteria used in the biological control of plant-parasitic nematodes: populations, mechanisms of action, and future prospectsFEMS MICROBIOLOGY ECOLOGY, Issue 2 2007Baoyu Tian Abstract As a group of important natural enemies of nematode pests, nematophagous bacteria exhibit diverse modes of action: these include parasitizing; producing toxins, antibiotics, or enzymes; competing for nutrients; inducing systemic resistance of plants; and promoting plant health. They act synergistically on nematodes through the direct suppression of nematodes, promoting plant growth, and facilitating the rhizosphere colonization and activity of microbial antagonists. This review details the nematophagous bacteria known to date, including parasitic bacteria, opportunistic parasitic bacteria, rhizobacteria, Cry protein-forming bacteria, endophytic bacteria and symbiotic bacteria. We focus on recent research developments concerning their pathogenic mechanisms at the biochemical and molecular levels. Increased understanding of the molecular basis of the various pathogenic mechanisms of the nematophagous bacteria could potentially enhance their value as effective biological control agents. We also review a number of molecular biological approaches currently used in the study of bacterial pathogenesis in nematodes. We discuss their merits, limitations and potential uses. [source] Inactivation of pqq genes of Enterobacter intermedium 60-2G reduces antifungal activity and induction of systemic resistanceFEMS MICROBIOLOGY LETTERS, Issue 1 2008Song Hee Han Abstract Enterobacter intermedium 60-2G, a phosphate solubilizing bacterium, has the ability to induce systemic resistance in plants against soft rot pathogen Erwinia carotovora. Glucose dehydrogenase, an enzyme that utilizes pyrroloquinoline quinone (PQQ) as a cofactor, is required for the synthesis of gluconic acid by E. intermedium 60-2G. Here, we report that the pqqA and pqqB genes are required for phosphate solubilization and induced systemic resistance against a soft rot pathogen in tobacco. Mutations in either the pqqA or pqqB gene abolished the production of 2-ketogluconic acid and eliminated the ability of E. intermedium to solubilize hydroxyapatite. Addition of gluconic acid to the growth media restored the ability of the pqqA mutant to produce 2-ketogluconic acid. Interestingly, both pqqA and pqqB mutants of E. intermedium lost their ability to inhibit the growth of the rice pathogen Magnaporthe grisea KI-409. Additionally, induced systemic resistance against the soft rot pathogen was attenuated in the pqq mutants. These functions were restored by complementation with the wild-type pqq gene cluster. Our findings suggest that PQQ plays an important function in beneficial traits including phosphate solubilization, antifungal activity, and induced systemic resistance of E. intermedium, possibly by acting as a cofactor for several enzymes including glucose dehydrogenase. [source] The development and endophytic nature of the fungus Heteroconium chaetospiraFEMS MICROBIOLOGY LETTERS, Issue 2 2005Teruyoshi Hashiba Abstract The root endophytic fungus Heteroconium chaetospira was isolated from roots of Chinese cabbage grown in field soil in Japan. This fungus penetrates through the outer epidermal cells of its host, passes into the inner cortex, and grows throughout the cortical cells, including those of the root tip region, without causing apparent pathogenic symptoms. There are no ultrastructural signs of host resistance responses. H. chaetospira has been recovered from 19 plant species in which there was no disruption of host growth. H. chaetospira has a symbiotic association with Chinese cabbage. The fungus provides nitrogen in exchange for carbon. These associations are beneficial for the inoculated plants, as demonstrated by increased growth rate. When used as a preinoculum, H. chaetospira suppresses the incidence of clubroot and Verticillium yellows when the test plant is post-inoculated with the causal agents of these diseases. H. chaetospira is an effective biocontrol agent against clubroot in Chinese cabbage at a low to moderate soil moisture range and a pathogen resting spore density of 105 resting spores per gram of soil in situ. Disease caused by Pseudomonas syringae pv. macricola and Alternaria brassicae on leaves can be suppressed by treatment with H. chaetospira. The fungus persists in the roots and induces systemic resistance to the foliar disease. [source] Low Systemic Vascular Resistance After Cardiopulmonary Bypass: Incidence, Etiology, and Clinical ImportanceJOURNAL OF CARDIAC SURGERY, Issue 5 2000T. Carrel M.D. The etiology is not completely elucidated and the clinical importance remains speculative. Methods: In this prospective clinical trial, we assessed the incidence of postoperative low systemic vascular resistance in 800 consecutive patients undergoing elective coronary artery bypass grafting and/or valve replacement. We have attempted to identify the predictive factors responsible for the presence of low systemic vascular resistance and we have examined the subsequent postoperative outcome of those patients who developed early postoperative vasoplegia. The severity of vasoplegia was divided into three groups according either to the value of systemic resistance and/or the dose of vasoconstrictive agents necessary to correct the hemodynamic. Results: Six hundred twenty-five patients (78.1%) did not develop vasoplegia, 115 patients (14.4%) developed a mild vasoplegia, and 60 patients (7.5%) suffered from severe vasoplegia. Low systemic vascular resistance did not affect hospital mortality but was the cause for delayed extubation and prolonged stay on the intensive care unit IICU). Logistic regression analysis identified temperature and duration of cardiopulmonary bypass, total cardioplegic volume infused, reduced left ventricular function, and preoperative treatment with angiotensin-converting enzyme (ACE)-inhibitors, out of 25 parameters, as predictive factors for early postoperative vasoplegia. Conclusion. The occurrence of low systemic vascular resistance following cardiopulmonary bypass is as high as 21.8%. The etiology of this clinical condition is most probably multifactorial. Mortality is not affected by vasoplegia, but there is a trend to higher morbidity and prolonged stay in the ICU. [source] Induction of Systemic Acquired Resistance in Arachis hypogaea L. by Sclerotium rolfsii Derived ElicitorsJOURNAL OF PHYTOPATHOLOGY, Issue 9 2010Durgesh Nandini Abstract Plants evolve a strategy to survive the attacks of potential pathogens by inducing the microbial signal molecules. In this study, plant defence responses were induced in four different varieties of Arachis hypogaea (J-11, GG-20, TG-26 and TPG41) using the fungal components of Sclerotium rolfsii in the form of fungal culture filtrate (FCF) and mycelial cell wall (MCW), and the levels of defence-related signal molecule salicylic acid (SA), marker enzymes such as peroxidase (POX), phenylalanine ammonia lyase (PAL), ,-1,3-glucanase and lignin were determined. There was a substantial fold increase in POX, PAL, SA, ,-1,3-glucanase and lignin content in FCF- and MCW-treated plants of all varieties of groundnut when compared to that of control plants. The enzyme activities were much higher in FCF-treated plants than in MCW-treated plants. The increase in fold activity of enzymes and signal molecule varied between different varieties. These results indicate that the use of fungal components (FCF and MCW) had successfully induced systemic resistance in the four different varieties of groundnut plants against Sclerotium rolfsii. [source] Multiple determinants influence root colonization and induction of induced systemic resistance by Pseudomonas chlororaphis O6MOLECULAR PLANT PATHOLOGY, Issue 6 2006SONG HEE HAN SUMMARY Colonization of the roots of tobacco by Pseudomonas chlororaphis O6 induces systemic resistance to the soft-rot pathogen, Erwinia carotovora ssp. carotovara SCC1. A screen of the transposon mutants of P. chlororaphis O6 showed mutants with about a fivefold reduction in ability to induce systemic resistance to the soft-rot disease. These mutations disrupted genes involved in diverse functions: a methyl-accepting chemotaxis protein, biosynthesis of purines, phospholipase C, transport of branched-chain amino acids and an ABC transporter. Additional mutations were detected in the intergenic spacer regions between genes encoding a GGDEF protein and fumarate dehydratase, and in genes of unknown function. The mutants in the ABC transporters did not display reduced root colonization. However, the other mutants had up to 100-fold reduced colonization levels. Generally the production of metabolites important for interactions in the rhizosphere, phenazines and siderophores, was not altered by the mutations. A reduced induction of systemic resistance by a purine biosynthesis mutant with a disrupted purM gene correlated with poor growth rate, lesser production of phenazines and siderophore and low levels of root colonization. These studies showed that multiple determinants are involved in the induction of systemic resistance, with there being a requirement for strong root colonization. [source] Induction of systemic protection against rust infection in broad bean by saccharin: effects on plant growth and developmentNEW PHYTOLOGIST, Issue 2 2005Celia Boyle Summary ,,Here, we examine the effect of saccharin on the induction of systemic resistance in broad bean (Vicia faba) to the rust fungus Uromyces viciae-fabae. ,,Saccharin was applied to beans at the three-leaf stage, either as a soil drench or by painting the solution on to first leaves. Plants were then challenge inoculated with the rust 1, 6, 10 and 14 d following saccharin treatment, after which they were harvested, assessed for the intensity of rust infection and plant growth measurements conducted. ,,Foliar application of saccharin did not induce systemic protection to rust infection until 14 d after application and was less effective than saccharin applied as a soil drench. When saccharin was applied as a drench, systemic protection was not observed until 6 d after application, but was still apparent in plants 14 d after application of the drench. ,,Irrespective of the method of application, saccharin had no significant effect on fresh and dry weights or leaf area of the plants. Saccharin applied as a drench did, however, reduce the number of leaflets produced. [source] Induction of systemic resistance in Arabidopsis thaliana in response to a culture filtrate from a plant growth-promoting fungus, Phoma sp.PLANT BIOLOGY, Issue 1 2009GS8- Abstract The plant growth-promoting fungus (PGPF), Phoma sp. GS8-3, isolated from a zoysia grass rhizosphere, is capable of protecting cucumber plants against virulent pathogens. This fungus was investigated in terms of the underlying mechanisms and ability to elicit systemic resistance in Arabidopsis thaliana. Root treatment of Arabidopsis plants with a culture filtrate (CF) from Phoma sp. GS8-3 elicited systemic resistance against the bacterial speck pathogen Pseudomonas syringae pv. tomato DC3000 (Pst), with restricted disease development and inhibited pathogen proliferation. Pathway-specific mutant plants, such as jar1 (jasmonic acid insensitive) and ein2 (ethylene insensitive), and transgenic NahG plants (impaired in salicylate signalling) were protected after application of the CF, demonstrating that these pathways are dispensable (at least individually) in CF-mediated resistance. Similarly, NPR1 interference in npr1 mutants had no effect on CF-induced resistance. Gene expression studies revealed that CF treatment stimulated the systemic expression of both the SA-inducible PR-1 and JA/ET-inducible PDF1.2 genes. However, pathogenic challenge to CF-treated plants was associated with potentiated expression of the PR-1 gene and down-regulated expression of the PDF1.2 gene. The observed down-regulation of the PDF1.2 gene in CF-treated plants indicates that there may be cross-talk between SA- and JA/ET-dependent signalling pathways during the pathogenic infection process. In conclusion, our data suggest that CF of Phoma sp. GS8-3 induces resistance in Arabidopsis in a manner where SA and JA/ET may play a role in defence signalling. [source] Gene Expression Analysis in Cucumber Leaves Primed by Root Colonization with Pseudomonas chlororaphis O6 upon Challenge-Inoculation with Corynespora cassiicolaPLANT BIOLOGY, Issue 2 2004M. S. Kim Abstract: Root colonization by Pseudomonas chlororaphis O6, a non-pathogenic rhizobacterium, induced systemic resistance in cucumber against target leaf spot caused by Corynespora cassiicola. A cDNA library was constructed using mRNA extracted from cucumber leaves 12 h after inoculation with C. cassiicola, using plants colonized by O6. To identify genes involved in O6-mediated induced systemic resistance (ISR), we employed a subtractive hybridization method using mRNAs extracted from pathogen-challenged cucumber leaves of plants lacking colonization. Differential screening of the cDNA library led to the isolation of six distinct genes encoding a GTP binding protein, a 60S ribosomal protein, a hypersensitive-induced reaction protein, a ubiquitin extension protein, a pyridine nucleotide-disulfide oxidoreductase, and a signal recognition particle receptor. Expression of these genes was not induced by O6 colonization alone. Rather, transcript accumulation of these genes increased significantly faster and stronger in the O6 colonized than in non-colonized plants after challenge infection. Therefore, O6-mediated ISR may be associated with an enhanced capacity for the rapid and effective activation of cellular defence responses after challenge inoculation. [source] Signal transduction downstream of salicylic and jasmonic acid in herbivory-induced parasitoid attraction by Arabidopsis is independent of JAR1 and NPR1PLANT CELL & ENVIRONMENT, Issue 9 2003R. M. P. VAN POECKE ABSTRACT Plants can defend themselves indirectly against herbivores by emitting a volatile blend upon herbivory that attracts the natural enemies of these herbivores, either predators or parasitoids. Although signal transduction in plants from herbivory to induced volatile production depends on jasmonic acid (JA) and salicylic acid (SA), the pathways downstream of JA and SA are unknown. Use of Arabidopsis provides a unique possibility to study signal transduction by use of signalling mutants, which so far has not been exploited in studies on indirect plant defence. In the present study it was demonstrated that jar1-1 and npr1-1 mutants are not affected in caterpillar (Pieris rapae)-induced attraction of the parasitoid Cotesia rubecula. Both JAR1 and NPR1 (also known as NIM1) are involved in signalling downstream of JA in induced defence against pathogens such as induced systemic resistance (ISR). NPR1 is also involved in signalling downstream of SA in defence against pathogens such as systemic acquired resistance (SAR). These results demonstrate that signalling downstream of JA and SA differs between induced indirect defence against herbivores and defence against pathogens such as SAR and ISR. Furthermore, it was demonstrated that herbivore-derived elicitors are involved in induced attraction of the parasitoid Cotesia rubecula [source] Resistance to Leptosphaeria maculans (phoma stem canker) in Brassica napus (oilseed rape) induced by L. biglobosa and chemical defence activators in field and controlled environmentsPLANT PATHOLOGY, Issue 3 2006S. Y. Liu Effects of pretreatment of Brassica napus leaves with ascospores of Leptosphaeria biglobosa or chemical defence activators [acibenzolar- S -methyl (ASM) or menadione sodium bisulphite (MSB)] on infection by ascospores of Leptosphaeria maculans (phoma stem canker) and development of disease were studied in controlled-environment (phoma leaf spot) and field (phoma leaf spot and stem canker) experiments. In controlled-environment experiments, pretreatment of oilseed rape leaves (cv. Madrigal) with L. biglobosa, ASM or MSB delayed the appearance of L. maculans phoma leaf spot lesions. These pretreatments also decreased the phoma leaf spot lesion area in both pretreated leaves (local effect) and untreated leaves (systemic effect). In winter oilseed rape field experiments in the 2002/03 and 2003/04 growing seasons, pretreatment with L. biglobosa or ASM in October/November decreased not only the number of phoma leaf spot lesions per leaf caused by L. maculans in autumn/winter, but also the severity of phoma stem canker in the subsequent spring/summer. Effects were greater in 2002/03 (when natural L. maculans ascospore release began in September 2002) than in 2003/04 (when ascospore release began in December following a period of dry weather in August/September 2003). These results suggest that pretreatment with biological or chemical defence activators can induce local and systemic resistance to L. maculans, with both short-term effects on the development of phoma leaf spotting and long-term effects on the development of stem canker 8 months later. [source] Menadione sodium bisulphite: a novel plant defence activator which enhances local and systemic resistance to infection by Leptosphaeria maculans in oilseed rapePLANT PATHOLOGY, Issue 4 2003A. A. Borges Pretreatment of the first true leaves of oilseed rape plants (Brassica napus cv. Bristol) with menadione sodium bisulphite (MSB) locally and systemically induced resistance, as shown by reduced lesion size and number, to infection by the fungal pathogen Leptosphaeria maculans, the causal agent of stem canker. Using a known systemic activator of salicylic acid-dependent PR-1 induction, acibenzolar- S -methyl (BTH; S -methylbenzo[1,2,3]thiadiazole-7-carbothiate) as a comparison, real-time PCR expression analysis of genes encoding a pathogenesis-related protein 1 (PR-1) and an ascorbate peroxidase (APX) demonstrated a systemic enhancement of APX expression in MSB-pretreated plants, with no effect on PR-1 expression, suggesting augmented reactive oxygen species production in MSB-pretreated plants. The results demonstrate MSB to be an effective resistance activator in oilseed rape, and potentially useful for the control of stem canker. [source] Effect of 2,6-dichloroisonicotinic acid, its formulation materials and benzothiadiazole on systemic resistance to alternaria leaf spot in cottonPLANT PATHOLOGY, Issue 2 2000E.S. Colson-Hanks A wettable powder (WP) formulation providing 5,25 ,g mL,1 of 2,6-dichloroisonicotinic acid (INA) and 15,75 ,g mL,1 of WP applied to cotton cotyledons significantly increased the resistance of the next two leaves to challenge inoculation by Alternaria macrospora. The wettable powder alone at 15,75 ,g mL,1 had a lesser effect. A wettable granule (WG) formulation supplying 35 ,g mL,1 of benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and 35 ,g mL,1 of WG, applied as a cotyledonary treatment, significantly reduced the formation of lesions on the subsequent two leaves when challenged with A. macrospora. The WG control had no effect. Each treatment except for the WG control also raised the activities of ,-1,3-glucanase in unchallenged leaf and stem tissue. Each of the components of the wettable powder without INA applied to cotyledons raised enzyme activities in the next leaves. Individual components, as suspensions of silicic acid and kaolin and solutions of the detergent Attisol II, the wetting agent Ultravon W300 and pure INA, applied to cotyledons increased the resistance of the next leaves to A. macrospora. The responsiveness of cotton to BTH and to each of the components of formulated INA is discussed in relation to knowledge of the effects of BTH and INA on other plants and to possible ways in which the other components of the wettable powder may affect the process of signalling for systemic resistance to disease. [source] Induced systemic resistance against three foliar diseases of Agrostis stolonifera by (2R,3R)-butanediol or an isoparaffin mixtureANNALS OF APPLIED BIOLOGY, Issue 2 2010A.M. Cortes-Barco Induced systemic resistance (ISR) is a type of plant defence mechanism typically activated by non-pathogenic root-associated micro-organisms and systemic priming of gene expression in response to subsequent pathogen challenge. ISR was found to be activated by PC1, a mixture of food-grade synthetic isoparaffins and (2R,3R)-butanediol, a volatile organic compound produced by bacteria. In controlled environment tests, application of PC1 or (2R,3R)-butanediol to the soil reduced the diseased leaf area of Agrostis stolonifera by 20,40% for the fungal pathogens, Microdochium nivale, Rhizoctonia solani or Sclerotinia homoeocarpa compared to the water control. In A. stolonifera, expression of the jasmonate synthesis-related genes, AsAOS1, encoding an allene oxide synthase, and AsOPR4, encoding a 12-oxo-phytodienoic acid reductase, and expression of a pathogenesis-related protein gene, AsGns5, encoding an acidic , -1,3-glucanase, were primed for increased expression by PC1 or (2R,3R)-butanediol when M. nivale was inoculated 7 days later. However, the compounds differed in their ability to induce expression prior to pathogen challenge. PC1 induced AsAOS1 expression upon treatment, whereas (2R,3R)-butanediol induced expression of AsOPR4 and AsGns5 upon treatment. These results indicate that both (2R,3R)-butanediol and PC1 can produce ISR in A. stolonifera but may do so through different mechanisms. [source] Suppression of southern corn leaf blight by a plant growth-promoting rhizobacterium Bacillus cereus C1LANNALS OF APPLIED BIOLOGY, Issue 1 2010Chien-Jui Huang Southern corn leaf blight (SCLB) is an important foliar disease of maize. In this study, an induced systemic resistance (ISR)-eliciting rhizobacterium Bacillus cereus C1L was used to protect maize against SCLB. Application of B. cereus C1L in maize rhizosphere effectively protected maize from SCLB under greenhouse and field conditions. The protection effect of B. cereus C1L was similar to that of Maneb (2 kg active ingredient per hectare), a recommended fungicide. Furthermore, possible factors of B. cereus C1L to elicit ISR and to promote plant growth were investigated. The results indicate that secreted factors and rhizosphere colonisation ability of B. cereus C1L are involved in ISR elicitation. In addition to biocontrol activity, B. cereus C1L was able to promote growth of maize in field. Compared with a non-treated control, leaf length, leaf width, plant height and fresh and dry weights of B. cereus C1L-treated corn plants significantly increased. Therefore, B. cereus C1L acts as a plant growth-promoting rhizobacterium of maize. [source] | |||||||||||||