Colonization Density Research Articles

Effects of avocado (Persea americana Mill.) scion on arbuscular mycorrhizal and root hair development in rootstock

ABSTRACTGrafting is an important process to propagate horticulture plants; however, the mechanism through which the scion affects the absorption of rootstock remains poorly understood. The effects of the scion on AM fungi types in the rhizosphere soil of rootstock and the absorption of mycorrhizal root were determined in this study. Composition of arbuscular mycorrhizal (AM) fungi, soil assessment, spore density, hyphal length density, glomalin-related soil protein (GRSP) content in rhizosphere soil, root hair morphology and AM colonisation rate were measured among ‘Kampong’ avocado rootstocks grafted with five scions and ‘Kampong’ seedling trees. Results showed the main types of AM fungi in avocado seedling trees and trees grafted with five scions were nearly identical. However, the proportion of main genera exhibited differences. In addition, alkali-hydrolysable N, alkali-hydrolysable P and available K in rhizosphere soil, root hair density, AM colonization, spore density, hyphal length and GRSP content suggested the absorption of ‘Kampong’ rootstocks grafted with ‘Monroe’, ‘Wilson seedless’, ‘Hass’ and ‘Tonnage’ possessed stronger absorption than ‘Kampong’ seedling trees because of high AM colonisation and root hair density. This study suggested scions regulated both the AM and root hair development systematically and laid the foundation for future research of AM-enhancing avocado production.

Exotic weeds and fluctuating microclimate can constrain native plant regeneration in urban forest restoration.

Restoring forest structure and composition is an important component of urban land management, but we lack clear understanding of the mechanisms driving restoration success. Here we studied two indicators of restoration success in temperate rainforests: native tree regeneration and epiphyte colonization. We hypothesized that ecosystem properties such as forest canopy openness, abundance of exotic herbaceous weeds, and the microclimate directly affect the density and diversity of native tree seedlings and epiphytes. Relationships between environmental conditions and the plant community were investigated in 27 restored urban forests spanning 3-70years in age and in unrestored and remnant urban forests. We used structural equation modelling to determine the direct and indirect drivers of native tree regeneration and epiphyte colonization in the restored forests. Compared to remnant forest, unrestored forest had fewer native canopy tree species, significantly more light reaching the forest floor annually, and higher exotic weed cover. Additionally, epiphyte density was lower and native tree regeneration density was marginally lower in the unrestored forests. In restored forests, light availability was reduced to levels found in remnant forests within 20years of restoration planting, followed shortly thereafter by declines in herbaceous exotic weeds and reduced fluctuation of relative humidity and soil temperatures. Contrary to expectations, canopy openness was only an indirect driver of tree regeneration and epiphyte colonization, but it directly regulated weed cover and microclimatic fluctuations, both of which directly drove the density and richness of regeneration and epiphyte colonization. Epiphyte density and diversity were also positively related to forest basal area, as large trees provide physical habitat for colonization. These results imply that ecosystem properties change predictably after initial restoration plantings, and that reaching critical thresholds in some ecosystem properties makes conditions suitable for the regeneration of late successional species, which is vital for restoration success and long-term ecosystem sustainability. Abiotic and biotic conditions that promote tree regeneration and epiphyte colonization will likely be present in forests with a basal area ≥27m2 /ha. We recommend that urban forest restoration plantings be designed to promote rapid canopy closure to reduce light availability, suppress herbaceous weeds, and stabilize the microclimate.

ИЗУЧЕНИЕ МЕЖВИДОВОЙ КОНКУРЕНЦИИ VIBRIO CHOLERAE В БИОПЛЕНКАХ

On the model of biofilms studied interspecific competition toxigenic Vibrio cholerae and the heterologous bacteria E. coli, Klebsiella spp. and Enterococcus spp. Biofilms formed on the plates of food grade plastic in sterile tap water. Ctx + vibrio number was determined by real time-PCR. It has been previously shown complete correlation between results and standard PCR plating on a nutrient agar. It was found that all toxigenic strains in interspecific competition conditions with a strain of E. coli formed biofilm with a density of colonization from 103 to 105 vibrios per cm2 plastic plate. Strains competitors for inhibitory activity against Vibrio have a pronounced heterogeneity. Toxigenic vibrio detection of resistance as part of a biofilm inhibitory activity of other heterologous microorganisms gives hope for successful use in the practice of surveillance of cholera a new type of traps based on the phenomenon of the formation of biofilms.

Microbiological analysis of dental plaque in children with Down syndrome

Topical focus of modern dentistry is improving the prevention of dental diseases in children with Down syndrome. The goal of this work is to assess the species composition of the microflora of dental plaque in children with Down syndrome in comparison with conditionally healthy children. Materials and methods. In this work we have used the results of bacteriological research of clinical material of 10 children with Down syndrome and 15 conditionally healthy children. Swabs from cervical part of the teeth have been taken with the help of a sterile disposable tampon. Microbiological research has included a discharge of microorganisms, identification by morphological, cultural and biochemical properties of cultures. The research has been conducted on clinical strains of microorganisms discharged from dental plaque in children with Down syndrome and conditionally healthy children. The results. In the investigated material of children with Down syndrome, we have detected gram-positive microorganisms, such as Streptococcus spp with α-hemolytic activity, Bacillus spp and Candida fungi, as well as gram-negative bacteria: E. aerogenes , K. pneumoniae, P. aeruginosa, Neisseria spp ( Table 1 ). In the microflora of dental plaque, facultative anaerobic microorganisms have been discharged more often than aerobes. Conclusions. In control and main group, dental plaque microflora is more often presented by associations of bacteria and Candida fungi. The discharge rate of Streptococcus spp with α-hemolytic activity and Candida albicans is equal in both groups. Nonpathogenic Neisseria species have been presented in 9.1 % of strains in the main group, whereas in the control group there have been 35 % of strains. In children with Down syndrome we have detected gram-negative bacilli – enterobacteria with a density of microbial colonization of E. aerogenes Ig (4.66 ± 0.6) cfu/g, pseudomonads and gram-positive spore-forming bacilli – Ig (5.0 ± 0.0) cfu/g, which are representatives of the allochthonous (transitory, fickle) microflora of the oral cavity. Their long stay in the oral cavity prevents the effect of nonspecific protective factors, as well as antagonistic activity of autochthonous microflora. In case of some disorders of physiological state, representatives of allochthonous microflora can linger in the oral cavity, multiply and cause pathological processes.

Competitive use of root exudates by Bacillus amyloliquefaciens with Ralstonia solanacearum decreases the pathogenic population density and effectively controls tomato bacterial wilt

Understanding the interactions between beneficial bacteria, plant pathogens, and root exudates is necessary for the optimization of the bio-control strategies targeted toward plant soil-borne diseases. In this study, we showed that the competitive use of root exudates by the antagonistic bacterial strain SQYUV 162 along with the pathogenic strain Ralstonia solanacearum affected the pathogenic population density and the pathogenicity of R. solanacearum. All of the tested organic acids induced chemotaxis in both SQYUV 162 and R. solanacearum. In addition, the growth of both SQYUV 162 and R. solanacearum was affected by the addition of organic acids. Strong chemotactic responses in SQYUV 162 and R. solanacearum were induced by malic acid and citric acid respectively. It was also observed that the addition of organic acids significantly induced the expression of several virulence-related genes and increased the population density of the pathogen on the roots, resulting in higher disease incidences in hydroponic experiments in comparison to a control. When SQYUV 162 was inoculated, however, both the expression of virulence-related genes and the population density of the pathogen decreased. The population density of SQYUV 162 also increased when roots were placed in contact with organic acids. The improved colonization density of SQYUV 162, as well as the decreased pathogenicity and population density of the pathogen, efficiently suppressed the incidence of bacterial wilt. The present results indicate that certain components of root exudates could suppress soil-borne diseases: by applying bacteria whose resource consumption profile overlaps that of plant pathogens, plant diseases may be better controlled.

Mucosal vaccination promotes clearance of Streptococcus agalactiae vaginal colonization

Group B Streptococcus (GBS) is a leading cause of morbidity and mortality in infants, and colonization of the maternal genital tract is the primary risk factor for newborn infection. Despite the importance of mucosal colonization in GBS pathogenesis, relevant host and bacterial factors are incompletely understood. We investigated the role of humoral immunity in clearance of vaginal colonization in vivo. B-cell-deficient mice or those lacking neonatal Fc-receptor, a mediator of IgG transport to the vaginal mucosa, exhibit prolonged GBS vaginal colonization compared to wild type animals. Intranasal but not intramuscular immunization induced systemic and mucosal immune responses and decreased GBS colonization duration without altering initial colonization density. Vaccine-induced clearance of GBS was serotype-specific, suggesting a role for anti-capsule antibodies in protection. Our results support a role for humoral immunity in GBS eradication from the female genital tract and suggest that mucosal vaccination may prime colonization clearance.

Protection against Streptococcus pneumoniae Invasive Pathogenesis by a Protein-Based Vaccine Is Achieved by Suppression of Nasopharyngeal Bacterial Density during Influenza A Virus Coinfection.

An increase in Streptococcus pneumoniae nasopharynx (NP) colonization density during a viral coinfection initiates pathogenesis. To mimic natural S. pneumoniae pathogenesis, we commensally colonized the NPs of adult C57BL/6 mice with S. pneumoniae serotype (ST) 6A or 8 and then coinfected them with mouse-adapted H1N1 influenza A virus (PR/8/34). S. pneumoniae established effective commensal colonization, and influenza virus coinfection caused S. pneumoniae NP density to increase, resulting in bacteremia and mortality. We then studied histidine triad protein D (PhtD), an S. pneumoniae adhesin vaccine candidate, for its ability to prevent invasive S. pneumoniae disease in adult and infant mice. In adult mice, the efficacy of PhtD vaccination was compared with that of PCV13. Vaccination with PCV13 led to a greater reduction of S. pneumoniae NP density (>2.5 log units) than PhtD vaccination (∼1-log-unit reduction). However, no significant difference was observed with regard to the prevention of S. pneumoniae bacteremia, and there was no difference in mortality. Depletion of CD4+ T cells in PhtD-vaccinated adult mice, but not PCV13-vaccinated mice, caused a loss of vaccine-induced protection. In infant mice, passive transfer of antisera or CD4+ T cells from PhtD-vaccinated adult mice led to a nonsignificant reduction in NP colonization density, whereas passive transfer of antisera and CD4+ T cells was needed to cause a significant reduction in NP colonization density. For the first time, these data show an outcome with regard to prevention of invasive S. pneumoniae pathogenesis with a protein vaccine similar to that which occurs with a glycoconjugate vaccine despite a less robust reduction in NP bacterial density.

The role of breakwaters on the rehabilitation of coastal and mangrove forests in West Kalimantan, Indonesia

The breakwaters, which were built by the government of West Kalimantan, Indonesia in late 1993 were aimed to protect the coast and mangrove forest. However, the effectiveness of building the breakwaters is not known because no measurement has been done. This study aimed to reveal the effectiveness of building breakwaters to protect the coast and its role in the rehabilitation of mangrove forest.The role of breakwaters in protecting the coast and rehabilitating the mangrove forest were assessed by comparing differences between the condition when there were no breakwaters versus condition after the breakwaters built. Beside building breakwaters, the government plant Rhizopora to restore the mangrove forest. The success rate of mangrove rehabilitation effort was determined by measuring density and distribution of Rhizophora and colonization of Avicennia marina. The study conducted using survey method with a landscape approach conducted in three bays of the South China Sea, West Kalimantan, Indonesia, which are: Penibung, Sungai Duri, and Karimunting. The measurement of parameters was conducted with purposive sampling technique based on perpendicular toward the sea area. The parameters measured were shoreline differences, the distribution of bottom and drift sediment, and the prediction of longshore sediment transport alongside the shore.The result showed that the breakwaters built in Karimunting and Penibung Bay were successful to reduce the amount of coastal erosion up to 70% within 22 years. On the contrary, the breakwaters built in the Bay of Sungai Duri could not reduce the coastal erosion. The effects of breakwaters on mangrove rehabilitation were clear, which can be observed on the colonization rate of Avicennia marina and reforestation of Rhizophora sp. in Karimunting Bay. The abrasion of shoreline still occurred although there were breakwaters built. It might be caused by the construction of breakwaters were segmented. The condition worsens by activities of beach sand excavation.

Spatiotemporal variation of arbuscular mycorrhizal fungal colonization in olive (Olea europaea L.) roots across a broad mesic-xeric climatic gradient in North Africa.

This study aims to determine the spatiotemporal dynamics of root colonization and spore density of arbuscular mycorrhizal fungi (AMF) in the rhizosphere of olive trees (Olea europaea) with different plantation ages and under different climatic areas in Algeria. Soil and root samples were seasonally collected from three olive plantations of different ages. Other samples were carried out in productive olive orchards cultivated under a climatic gradient (desertic, semi-arid, subhumid, and humid). The olive varieties analysed in this study were Blanquette, Rougette, Chemlel and the wild-olive. Spore density, mycorrhization intensity (M%), spore diversity and the most probable number (MPN) were determined. Both the intensity of mycorrhizal colonization and spore density increased with the increase of seasonal precipitation and decreased with the increase of air temperature regardless of the climatic region or olive variety. The variety Rougette had the highest mycorrhizal levels in all plantation ages and climates. Spore community was composed of the genera Rhizophagus, Funneliformis, Glomus, Septoglomus, Gigaspora, Scutellospora and Entrophospora. The genus Glomus, with four species, predominated in all climate regions. Spores of Gigaspora sp. and Scutellospora sp. were the most abundant in desertic plantations. Statistical models indicated a positive relationship between spore density and M% during spring and winter in young seedlings and old plantations. A significant positive relationship was found between MPN and spore density under different climates. For a mycotrophic species, the rhizosphere of olive trees proved to be poor in mycorrhiza in terms of mycorrhizal colonization and numbers of the infective AMF propagules.

PCV13-vaccinated children still carrying PCV13 additional serotypes show similar carriage density to a control group of PCV7-vaccinated children

BackgroundIn addition to reducing vaccine-type nasopharyngeal carriage rates, pneumococcal conjugate vaccines (PCVs) may decrease carriage density in vaccinated individuals still carrying vaccine serotypes. However, reduction of carriage density has not been systematically studied. This study compared the effect of PCV13 versus PCV7 on carriage density of the serotypes in PCV13 that are not included in PCV7. MethodsThis randomized, double-blind study was conducted in southern Israel and included Jewish and Bedouin subjects. Per protocol, 881 and 873 infants received PCV13 and PCV7, respectively, at ages 2, 4, 6, and 12months. Nasopharyngeal cultures at ages 7, 12, 13, 18, and 24months were plated using the 4-quadrant semiquantitative method and graded 0 (negative) to 4 (growth in all plate quadrants). In this post hoc analysis, the least squares means of cumulative colonization densities per serotype and serotype combination of the total population and each ethnic subpopulation in each vaccine group were calculated, and differences between vaccine groups derived from a linear model. ResultsPCV13-vaccinated children still carrying the 6 additional PCV13 serotypes unique to PCV13 showed no significant differences in carriage density compared with the PCV7-vaccinated control group. No differences in carriage density were shown between Jewish and Bedouin subpopulations despite higher carriage rates among Bedouin subjects. ConclusionsAlthough PCV13 vaccination reduces vaccine-type carriage compared with PCV7 vaccination by reducing nasopharyngeal acquisition of the additional PCV13 serotypes as previously reported, the current study lacks evidence of a decrease in carriage density of these serotypes when acquired in vaccinated children. Despite the lack of effect on carriage density observed, surveillance data suggest a dramatic decrease in disease rates after PCV implementation. Thus, the current analysis suggests that PCV’s impact on carriage density has minimal or no impact on vaccine success. (www.ClinicalTrials.gov: NCT00508742)

The Effect of Distance from River on Soil Physiochemical Properties, Root Colonization and Spore density of Arbuscular Mycorrhizal Fungi Associated with Salt Cedar

The Effect of Distance from River on Soil Physiochemical Properties, Root Colonization and Spore density of Arbuscular Mycorrhizal Fungi Associated with Salt Cedar

Risk Factors for Influenza-Associated Severe Acute Respiratory Illness Hospitalization in South Africa, 2012-2015.

BackgroundData on risk factors for influenza-associated hospitalizations in low- and middle-income countries are limited.MethodsWe conducted active syndromic surveillance for hospitalized severe acute respiratory illness (SARI) and outpatient influenza-like illness (ILI) in 2 provinces of South Africa during 2012–2015. We compared the characteristics of influenza-positive patients with SARI to those with ILI to identify factors associated with severe disease requiring hospitalization, using unconditional logistic regression.ResultsDuring the study period, influenza virus was detected in 5.9% (110 of 1861) and 15.8% (577 of 3652) of SARI and ILI cases, respectively. On multivariable analysis factors significantly associated with increased risk of influenza-associated SARI hospitalization were as follows: younger and older age (<6 months [adjusted odds ratio {aOR}, 37.6], 6–11 months [aOR, 31.9], 12–23 months [aOR, 22.1], 24–59 months [aOR, 7.1], and ≥65 years [aOR, 40.7] compared with 5–24 years of age), underlying medical conditions (aOR, 4.5), human immunodeficiency virus infection (aOR, 4.3), and Streptococcus pneumoniae colonization density ≥1000 deoxyribonucleic acid copies/mL (aOR, 4.8). Underlying medical conditions in children aged <5 years included asthma (aOR, 22.7), malnutrition (aOR, 2.4), and prematurity (aOR, 4.8); in persons aged ≥5 years, conditions included asthma (aOR, 3.6), diabetes (aOR, 7.1), chronic lung diseases (aOR, 10.7), chronic heart diseases (aOR, 9.6), and obesity (aOR, 21.3). Mine workers (aOR, 13.8) and pregnant women (aOR, 12.5) were also at increased risk for influenza-associated hospitalization.ConclusionsThe risk groups identified in this study may benefit most from annual influenza immunization, and children <6 months of age may be protected through vaccination of their mothers during pregnancy.

Arbuscular Mycorrhizal Fungi spores diversity and AMF infection in some medicinal plants of District Charsadda KPK

An investigation has been made about the Arbuscular Mycorrhizal Fungi (AMF) spore population and root colonization in 20 medicinal plants selected and collected from district Charsadda at early winter and summer seasons during session 2014-2015. The spore density of AMF ranged from 80 spores per 100gm -1 , and root colonization from 20-80%. The lowest spore density was recorded in Cestrum nocturnum, Ficus carica, Aquilaria agallocha and the highest spore density was recorded in Sedum dendroideum, Cannabis sativa, Triticum aestivum, and Mentha longifolia, Withania somnifera while absent in Brassica campestris, Amaranthus viridis. The spore density of AMF and root colonization by these fungi varied from species to species, season to season, and also affected by host plant growth stages (vegetative-fruiting).AM fungi association was more observed at fruiting stage and low at vegetative and flowering phases of host. The most dominant species of AMF were Glomus followed by Sclerocystis and Acaulospora species.

Comparison of cellular responses to Xanthomonas perforans infection between resistant and susceptible tomato accessions

Bacterial spot of tomato (Solanum lycopersicum L.) caused by several Xanthomonas species is one of the most destructive diseases. Genes regulating the hypersensitive resistance and field resistance to X. perforans race T3 have been intensively investigated over the last decade. However, a comparative analysis of cellular responses to the pathogen in susceptible and resistant hosts has not been completed, which prevents the detailed understanding of the interactions between the pathogen and tomato plants. In this study, the characteristics of lesions, stomata, and pathogen colonization in hypersensitive response (HR) PI 128216, field-resistant PI 114490, and susceptible OH 88119 tomato plants after inoculation with green fluorescent protein-labeled X. perforans race T3 bacteria were investigated. Significant differences in developmental processes and the micromorphology of spot lesions among three tomato lines were observed. Our results suggested that the faster lesion development in OH 88119 plants compared with that of the other two lines was associated with a greater increase in the stomatal apertures over a longer period following bacterial inoculation. The depth of bacterial colonization and pathogen density inside infected leaves in OH 88119 were also significantly different from that of resistant tomato plants. Determination of the ultrastructural responses to X. perforans among three tomato lines revealed that cell wall defense response was the main difference between resistant and susceptible tomato lines. These results may provide fundamental information for understanding the cellular and molecular mechanisms regulating tomato responses to X. perforans race T3.

Reproduction of Walnut Twig Beetle in Black Walnut and Butternut

The walnut twig beetle [WTB (Pityophthorus juglandis Blackman)] is the primary insect vector for a pathogen that causes thousand cankers disease (TCD), a disease complex that leads to mortality in species of walnut (Juglans L.). We performed field and laboratory trials to determine if reproduction by WTB varies between two black walnut (Juglans nigra L.) parent trees of a full-sib mapping population of 323 offspring, and between black walnut and butternut (Juglans cinerea L.). These two tree species are native to eastern North America. In field trials, we found no significant differences in colonization density or mean number of adult offspring per female among branch sections from black walnut parent trees or among branch sections from black walnut and butternut, respectively. In laboratory trials with controlled colonization densities of WTB, we found that significantly fewer adult offspring developed in branch sections of the black walnut maternal ‘Sparrow’ parent than the paternal ‘Schessler’ parent over three summer months and one winter month. In the field, high colonization densities likely limited reproduction due to increased intraspecific competition beneath the bark. In the laboratory, where we established a lower colonization density, reproduction was likely influenced by differences in host quality. In laboratory trials, no differences were detected in the number of adult offspring emerging from black walnut and butternut accessions. This finding suggests that butternut is a suitable host for WTB. Future screening of the full-sib mapping population of 323 offspring of black walnut parent trees for WTB resistance is a warranted next step in developing alternative management strategies for TCD in black walnut.

Effects of Arbuscular Mycorrhizal Fungus and Phosphate-Solubilizing Fungus on the Nutrient Uptake and Growth of Beach Plum (Prunus Maritima) Seedlings under NaCl Stress

The objective of this work was to study the effects of inoculation with an arbuscular mycorrhizal fungus (AMF), Glomus mosseae, and/or a phosphate-solubilising fungus (PSF), Mortierella sp. SM-1, on the nutrient uptake and growth of beach plum (Prunus maritima) when grown under 1% (w/v) NaCl stress. High concentration of NaCl (200 mMol) treatments adversely inhibited colonizations and spore densities by AMF or/and PSF, as well as the nutrient uptake of N, Ca, Mg, Cu, Fe, Zn and Mn nutrient acquisition, resulting in an important reduction in shoot and root dry biomass. Plants inoculated with AMF or/and PSF strongly promoted AM colonization and spore density, plant dry biomass and nutrient uptake by P. maritima. Dual inoculation of AMF and PSF showed significant higher effects on variation of the ion concentration (N, Ca, Mg, Cu, Fe, Zn and Mn) and plant growth indexes. It is concluded that AMF inoculation with PSF application could synergistically enhance the nutrient uptake and growth of plants.

Production of native arbuscular mycorrhizal fungi inoculum under different environmental conditions.

In order to obtain an arbuscular mycorrhizal fungi (AMF) native inoculum from Sierra de Moa and determine the most appropriate conditions for its big scale production, four light and temperature combinations were tested in three plant species (Calophyllum antillanum, Talipariti elatum and Paspalum notatum). Growth and development parameters, as well as the mycorrhizal functioning of the seedlings were evaluated. The natural light treatment under high temperatures (L-H) was the most suitable for the growth and development of the three plant species, showing the highest total biomass values, mainly of root, and a positive root-shoot ratio balance. This treatment also promoted higher values of root mycorrhizal colonization, external mycelium and AMF spore density. A total of 38 AMF species were identified among the plants and environmental conditions tested. Archaeospora sp.1, Glomus sp.5, Glomus brohultii and G. glomerulatum were observed in all the treatments. The L-H condition can be recommended for native inoculum production, as it promotes a better expression of the AM symbiosis and an elevated production of mycorrhizal propagules.

Nasopharyngeal Pneumococcal Density and Evolution of Acute Respiratory Illnesses in Young Children, Peru, 2009-2011.

We examined nasopharyngeal pneumococcal colonization density patterns surrounding acute respiratory illnesses (ARI) in young children in Peru. Pneumococcal densities were dynamic, gradually increasing leading up to an ARI, peaking during the ARI, and decreasing after the ARI. Rhinovirus co-infection was associated with higher pneumococcal densities.

TLR9 activation suppresses inflammation in response to Helicobacter pylori infection.

Helicobacter pylori (H. pylori) induces chronic gastritis in humans, and infection can persist for decades. One H. pylori strain-specific constituent that augments disease risk is the cag pathogenicity island. The cag island encodes a type IV secretion system (T4SS) that translocates DNA into host cells. Toll-like receptor 9 (TLR9) is an innate immune receptor that detects hypo-methylated CpG DNA motifs. In this study, we sought to define the role of the H. pylori cag T4SS on TLR9-mediated responses in vivo. H. pylori strain PMSS1 or its cagE- mutant, which fails to assemble a T4SS, were used to infect wild-type or Tlr9-/- C57BL/6 mice. PMSS1-infected Tlr9-/- mice developed significantly higher levels of inflammation, despite similar levels of colonization density, compared with PMSS1-infected wild-type mice. These changes were cag dependent, as both mouse genotypes infected with the cagE- mutant only developed minimal inflammation. Tlr9-/- genotypes did not alter the microbial phenotypes of in vivo-adapted H. pylori strains; therefore, we examined host immunological responses. There were no differences in levels of TH1 or TH2 cytokines in infected mice when stratified by host genotype. However, gastric mucosal levels of IL-17 were significantly increased in infected Tlr9-/- mice compared with infected wild-type mice, and H. pylori infection of IL-17A-/- mice concordantly led to significantly decreased levels of gastritis. Thus loss of Tlr9 selectively augments the intensity of IL-17-driven immune responses to H. pylori in a cag T4SS-dependent manner. These results suggest that H. pylori utilizes the cag T4SS to manipulate the intensity of the host immune response.

Mycorrhiza consortia suppress the fusarium root rot (Fusarium solani f. sp. Phaseoli) in common bean (Phaseolus vulgaris L.)

The ability of Arbuscular Mycorrhizal Fungi (AMF) to alleviate the lethal effects incited by root pathogens in a range of plant hosts has been demonstrated. Accumulated evidence also shows that multiple rather than single AMF species exhibit greater potential against pathogens and could mimic natural systems. Nevertheless, it is well established that the effectiveness of a consortium of beneficial organisms is function of interaction among the partners and the involved host. In the present study, four AMF formulations made up of three strains each (1:1:1 w/w) from propagated units of selected AMF strains, Glomus intraradices, Glomus hoi, Gigaspora margarita, and Scutellospora gigantea were evaluated in enhancing common bean (Phaseolus vulgaris L.) growth and biocontrol vis-à-vis Fusariumsolani under greenhouse conditions. The results revealed that all the mycorrhizal preparations significantly reduced the levels of disease severity and incidence in infected bean plants. The biocontrol efficiency of AMF was a function of genera diversity. Though, either neutral or significantly increased growth parameters were recorded upon mycorrhizal colonization. The rhyzospheric competence (root colonization and spore density) of the mycorrhizal formulations was negatively affected upon Fusarium solani inoculation. Moreover, the total soluble phenols and flavonoids contents as well as the specific activity of Phenylalanine Ammonia Lyase (PAL) were boosted after mycorrhizal colonization, indicating the strengthening of plant immune system against the pathogen. Further studies should confirm our formulations after open field assays as alternatives to agrochemicals.