Background
Since the 1980s, numerous mutualistic
Pseudomonas
spp. strains have been used in studies on the biology of plant growth-promoting rhizobacteria (PGPR) and their interactions with host ...plants. In 1988, a strain from the
Pseudomonas fluorescens
group, WCS417, was isolated from lesions of wheat roots growing in a take-all disease-suppressive soil. In subsequent trials, WCS417 limited the build-up of take-all disease in field-grown wheat and significantly increased wheat yield. In 1991, WCS417 was featured in one of the first landmark studies on rhizobacteria-induced systemic resistance (ISR), in which it was shown to confer systemic immunity in carnation (
Dianthus caryophyllus
) against Fusarium wilt. The discovery that WCS417 conferred systemic immunity in the model plant species
Arabidopsis thaliana
in 1996 incited intensive research on the molecular mechanisms by which PGPR promote plant growth and induce broad-spectrum disease resistance in plants. Since then, the strain name appeared in over 750 studies on beneficial plant-microbe interactions.
Scope
In this review, we will highlight key discoveries in plant-microbe interactions research that have emerged from over 30 years of research featuring WCS417 as a model rhizobacterial strain. WCS417 was instrumental in improving our understanding of the microbial determinants that are involved in root colonization and the establishment of mutually beneficial interactions with the host plant. The model strain also provided novel insight into the molecular mechanisms of plant growth promotion and the onset and expression of rhizobacteria-ISR. More recently, WCS417 has been featured in studies on host immune evasion during root colonization, and chemical communication in the rhizosphere during root microbiome assembly.
Conclusions
Numerous studies on the modes of action of WCS417 have provided major conceptual advances in our understanding of how free-living mutualists colonize the rhizosphere, modulate plant immunity, and promote plant growth. The concepts may prove useful in our understanding of the molecular mechanisms involved in other binary plant-beneficial microbe interactions, and in more complex microbial community contexts, such as the root microbiome.
Jasmonic acid (JA) is a critical hormonal regulator of plant growth and defense. To advance our understanding of the architecture and dynamic regulation of the JA gene regulatory network, we ...performed a high-resolution RNA-seq time series of methyl JA-treated Arabidopsis thaliana at 15 time points over a 16-h period. Computational analysis showed that methyl JA (MeJA) induces a burst of transcriptional activity, generating diverse expression patterns over time that partition into distinct sectors of the JA response targeting specific biological processes. The presence of transcription factor (TF) DNA binding motifs correlated with specific TF activity during temporal MeJA-induced transcriptional reprogramming. Insight into the underlying dynamic transcriptional regulation mechanisms was captured in a chronological model of the JA gene regulatory network. Several TFs, including MYB59 and bHLH27, were uncovered as early network components with a role in pathogen and insect resistance. Analysis of subnetworks surrounding the TFs ORA47, RAP2.6L, MYB59, and ANAC055, using transcriptome profiling of overexpressors and mutants, provided insights into their regulatory role in defined modules of the JA network. Collectively, our work illuminates the complexity of the JA gene regulatory network, pinpoints and validates previously unknown regulators, and provides a valuable resource for functional studies on JA signaling components in plant defense and development.
Walking Without Awareness Harms, Ilse M; van Dijken, Joke H; Brookhuis, Karel A ...
Frontiers in psychology,
08/2019, Letnik:
10
Journal Article
Recenzirano
Odprti dostop
Pedestrians are commonly engaged in other activities while walking. The current study assesses (1) whether pedestrians are sufficiently aware of their surroundings to successfully negotiate obstacles ...in a city, and (2) whether various common walking practices affect awareness of obstacles and, or, avoidance behavior. To this end, an obstacle, i.e., a signboard was placed on a pavement in the city centre of Utrecht, the Netherlands. The behavioral measure consisted of the distance to the signboard before pedestrians moved to avoid it. After passing, participants were interviewed to obtain thought samples, self-reported route familiarity, a confirmation of secondary task engagement, and to assess awareness through recall and recognition of the signboard and its text. In this study 234 pedestrians participated. More than half of the participants (53.8%) was unaware of the signboard, still none of them had bumped into it. Mind wandering, being engaged in secondary tasks such as talking with a companion or using a mobile phone, and being familiar with a route, did not affect awareness nor avoidance behavior. In conclusion, despite being very common there was no evidence that
necessarily results in risk. The absence of awareness does not imply any absence of cognitive and perceptual processing. Pedestrians are still capable of successfully avoiding obstacles in their path, even in visually more challenging environments such as a city centre. It is argued that this is because walking consists of highly automated, skilled behavior.
SUMMARY
The plant hormone abscisic acid (ABA) regulates essential processes in plant development and responsiveness to abiotic and biotic stresses. ABA perception triggers a post‐translational ...signaling cascade that elicits the ABA gene regulatory network (GRN), encompassing hundreds of transcription factors (TFs) and thousands of transcribed genes. To further our knowledge of this GRN, we performed an RNA‐seq time series experiment consisting of 14 time points in the 16 h following a one‐time ABA treatment of 5‐week‐old Arabidopsis rosettes. During this time course, ABA rapidly changed transcription levels of 7151 genes, which were partitioned into 44 coexpressed modules that carry out diverse biological functions. We integrated our time‐series data with publicly available TF‐binding site data, motif data, and RNA‐seq data of plants inhibited in translation, and predicted (i) which TFs regulate the different coexpression clusters, (ii) which TFs contribute the most to target gene amplitude, (iii) timing of engagement of different TFs in the ABA GRN, and (iv) hierarchical position of TFs and their targets in the multi‐tiered ABA GRN. The ABA GRN was found to be highly interconnected and regulated at different amplitudes and timing by a wide variety of TFs, of which the bZIP family was most prominent, and upregulation of genes encompassed more TFs than downregulation. We validated our network models in silico with additional public TF‐binding site data and transcription data of selected TF mutants. Finally, using a drought assay we found that the Trihelix TF GT3a is likely an ABA‐induced positive regulator of drought tolerance.
Significance Statement
The hormone abscisic acid (ABA) regulates many plant stress responses and plant development by activating a complex gene regulatory network. We unveiled key players and their hierarchy in the ABA network. For this, we generated high‐density RNA‐seq time series data of mature ABA‐treated Arabidopsis thaliana leaves and used existing and newly developed methods to integrate the transcriptional dynamics with publicly available TF‐binding data and RNA‐seq data of ABA‐treated plants inhibited in translation.
Currently licensed influenza vaccines mainly induce antibodies against highly variable epitopes. Due to antigenic drift, protection is subtype or strain-specific and regular vaccine updates are ...required. In case of antigenic shifts, which have caused several pandemics in the past, completely new vaccines need to be developed. We set out to develop a vaccine that provides protection against a broad range of influenza viruses. Therefore, highly conserved parts of the influenza A virus (IAV) were selected of which we constructed antibody and T cell inducing peptide-based vaccines. The B epitope vaccine consists of the highly conserved HA2 fusion peptide and M2e peptide coupled to a CD4 helper epitope. The T epitope vaccine comprises 25 overlapping synthetic long peptides of 26-34 amino acids, thereby avoiding restriction for a certain MHC haplotype. These peptides are derived from nucleoprotein (NP), polymerase basic protein 1 (PB1) and matrix protein 1 (M1). C57BL/6 mice, BALB/c mice, and ferrets were vaccinated with the B epitopes, 25 SLP or a combination of both. Vaccine-specific antibodies were detected in sera of mice and ferrets and vaccine-specific cellular responses were measured in mice. Following challenge, both mice and ferrets showed a reduction of virus titers in the lungs in response to vaccination. Summarizing, a peptide-based vaccine directed against conserved parts of influenza virus containing B and T cell epitopes shows promising results for further development. Such a vaccine may reduce disease burden and virus transmission during pandemic outbreaks.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Bacterial flagellin molecules are strong inducers of innate immune responses in both mammals and plants. The opportunistic pathogen Pseudomonas aeruginosa secretes an alkaline protease called AprA ...that degrades flagellin monomers. Here, we show that AprA is widespread among a wide variety of bacterial species. In addition, we investigated the role of AprA in virulence of the bacterial plant pathogen P. syringae pv. tomato DC3000. The AprA-deficient DC3000 ΔaprA knockout mutant was significantly less virulent on both tomato and Arabidopsis thaliana. Moreover, infiltration of A. thaliana Col-0 leaves with DC3000 ΔaprA evoked a significantly higher level of expression of the defense-related genes FRK1 and PR-1 than did wild-type DC3000. In the flagellin receptor mutant fls2, pathogen virulence and defense-related gene activation did not differ between DC3000 and DC3000 ΔaprA. Together, these results suggest that AprA of DC3000 is important for evasion of recognition by the FLS2 receptor, allowing wild-type DC3000 to be more virulent on its host plant than AprA-deficient DC3000 ΔaprA. To provide further evidence for the role of DC3000 AprA in host immune evasion, we overexpressed the AprA inhibitory peptide AprI of DC3000 in A. thaliana to counteract the immune evasive capacity of DC3000 AprA. Ectopic expression of aprI in A. thaliana resulted in an enhanced level of resistance against wild-type DC3000, while the already elevated level of resistance against DC3000 ΔaprA remained unchanged. Together, these results indicate that evasion of host immunity by the alkaline protease AprA is important for full virulence of strain DC3000 and likely acts by preventing flagellin monomers from being recognized by its cognate immune receptor.
Objective
Previous research reported cognitive and psychomotor impairments in long‐term users of benzodiazepine receptor agonists (BZRAs). This article explores the role of acute intoxication and ...clinical complaints.
Methods
Neurocognitive and on‐road driving performance of 19 long‐term (≥6 months) regular (≥twice weekly) BZRA users with estimated plasma concentrations, based on self‐reported use, exceeding the therapeutic threshold (CBZRA+), and 31 long‐term regular BZRA users below (CBZRA−), was compared to that of 76 controls.
Results
BZRA users performed worse on tasks of response speed, processing speed, and sustained attention. Age, but not CBZRA or self‐reported clinical complaints, was a significant covariate. Road‐tracking performance was explained by CBZRA only. The CBZRA + group exhibited increased mean standard deviation of lateral position comparable to that at blood‐alcohol concentrations of 0.5 g/L.
Conclusions
Functional impairments in long‐term BZRA users are not attributable to self‐reported clinical complaints or estimated BZRA concentrations, except for road‐tracking, which was impaired in CBZRA + users. Limitations to address are the lack of assessment of objective clinical complaints, acute task related stress, and actual BZRA plasma concentrations. In conclusion, the results confirm previous findings that demonstrate inferior performance across several psychomotor and neurocognitive domains in long‐term BZRA users.
Main conclusion
Carbonic anhydrases CA1 and CA4 attenuate plant immunity and can contribute to altered disease resistance levels in response to changing atmospheric CO
2
conditions.
β-Carbonic ...anhydrases (CAs) play an important role in CO
2
metabolism and plant development, but have also been implicated in plant immunity. Here we show that the bacterial pathogen
Pseudomonas syringae
and application of the microbe-associated molecular pattern (MAMP) flg22 repress
CA1
and
CA4
gene expression in
Arabidopsis thaliana
. Using the CA double-mutant
ca1ca4,
we provide evidence that CA1 and CA4 play an attenuating role in pathogen- and flg22-triggered immune responses. In line with this,
ca1ca4
plants exhibited enhanced resistance against
P. syringae
, which was accompanied by an increased expression of the defense-related genes
FRK1
and
ICS1.
Under low atmospheric CO
2
conditions (150 ppm), when CA activity is typically low, the levels of
CA1
transcription and resistance to
P. syringae
in wild-type Col-0 were similar to those observed in
ca1ca4.
However, under ambient (400 ppm) and elevated (800 ppm) atmospheric CO
2
conditions,
CA1
transcription was enhanced and resistance to
P. syringae
reduced. Together, these results suggest that CA1 and CA4 attenuate plant immunity and that differential
CA
gene expression in response to changing atmospheric CO
2
conditions contribute to altered disease resistance levels.
Highlights ► NonaMen has the potential to broadly protect against MenB disease. ► Nonamen was considered effective and safe in rabbits and mice. ► Risks-benefit balance favors use of plain NonaMen ...without an aluminium adjuvant.
Neisseria meningitidis and Bordetella pertussis are Gram-negative bacterial pathogens that can cause serious diseases in humans. N. meningitidis outer membrane vesicle (OMV) vaccines and whole cell ...pertussis vaccines have been successfully used in humans to control infections with these pathogens. The mechanisms behind their effectiveness are poorly defined. Here we investigated the role of Toll-like receptor (TLR) 2 and TLR4 in the induction of immune responses in mice after immunization with these vaccines. Innate and adaptive immune responses were compared between wild type mice and mice deficient in TLR2, TLR4, or TRIF. TRIF-deficient and TLR4-deficient mice showed impaired immunity after immunization. In contrast, immune responses were not lower in TLR2-/- mice but tended even to be higher after immunization. Together our data demonstrate that TLR4 activation contributes to the immunogenicity of the N. meningitidis OMV vaccine and the whole cell pertussis vaccine, but that TLR2 activation is not required.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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