scholarly journals Contrasting patterns of microbial dominance in the Arabidopsis thaliana phyllosphere

2021 ◽  
Author(s):  
Derek S Lundberg ◽  
Roger de Pedro Jové ◽  
Pratchaya Pramoj Na Ayutthaya ◽  
Talia L Karasov ◽  
Or Shalev Skriptchak ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Biotic Interactions ◽  
Late Summer ◽  
Amplicon Sequencing ◽  
Secretion Systems ◽  
Bacterial Populations ◽  
Protective Properties ◽  
Genomic Features ◽  
Local Plant ◽  
Protein Secretion Systems

Pseudomonas and Sphingomonas are among the most abundant bacterial genera in the phyllosphere of wild Arabidopsis thaliana. Relative to Pseudomonas, the ecology of Sphingomonas and its interaction with plants remains elusive, despite its global ubiquity and known representatives of plant-beneficial strains. We analyzed the genomic features of over 400 endophytic Sphingomonas isolates collected from A. thaliana and neighboring plants, revealing high intergenomic diversity compared to much more homogenous Pseudomonas populations on the same plants. Variation in plasmid complement and additional genomic features suggest high adaptability, and the widespread presence of protein secretion systems hints at frequent biotic interactions. While some of the isolates showed plant-protective properties, this was a rare trait. To begin to understand the bacterial populations at the investigated A. thaliana sites and the alternate hosts of these strains when A. thaliana becomes limiting, we employed amplicon sequencing and a novel bulk-culturing metagenomics approach on A. thaliana and neighboring plants, both in spring when A. thaliana was flowering and in late summer before the emergence of the A. thaliana winter cohort. Our data reveal that Sphingomonas and Pseudomonas strains from A. thaliana not only survive, but also thrive on other diverse local plant hosts, suggesting that leaf-to-leaf transmission from these biotic reservoirs may be a major source of microbes to the next generation.

scholarly journals Characterization of the early response of Arabidopsis thaliana to Dickeya dadantii infection using expression profiling

2018 ◽  
Author(s):  
Frédérique Van Gijsegem ◽  
Frédérique Bitton ◽  
Anne-Laure Laborie ◽  
Yvan Kraepiel ◽  
Jacques Pédron
Keyword(s):  
Arabidopsis Thaliana ◽  
Early Stage ◽  
Plant Defence ◽  
Plant Responses ◽  
Type I ◽  
In Planta ◽  
Secretion Systems ◽  
Dickeya Dadantii ◽  
A Genome

AbstractTo draw a global view of plant responses to interactions with the phytopathogenic enterobacterale Dickeya dadantii, a causal agent of soft rot diseases on many plant species, we analysed the early Arabidopsis responses to D. dadantii infection. We performed a genome-wide analysis of the Arabidopsis thaliana transcriptome during D. dadantii infection and conducted a genetic study of identified responses.A limited set of genes related to plant defence or interactions with the environment were induced at an early stage of infection, with an over-representation of genes involved in both the metabolism of indole glucosinolates (IGs) and the jasmonate (JA) defence pathway. Bacterial type I and type II secretion systems are required to trigger the induction of IG and JA-related genes while the type III secretion system appears to partially inhibit these defence pathways. Using Arabidopsis mutants impaired in JA biosynthesis or perception, we showed that induction of some IG metabolism genes was COI1-dependent but, surprisingly, JA-independent. Moreover, characterisation of D. dadantii disease progression in Arabidopsis mutants impaired in JA or IG pathways showed that JA triggers an efficient plant defence response that does not involve IGs.The induction of the IG pathway by bacterial pathogens has been reported several times in vitro. This study shows for the first time, that this induction does indeed occur in planta, but also that this line of defence is ineffective against D. dadantii infection, in contrast to its role to counteract herbivorous or fungal pathogen attacks.

Super-resolution imaging of bacterial pathogens and visualization of their secreted effectors

2020 ◽  
Author(s):  
Moirangthem Kiran Singh ◽  
Linda J Kenney
Keyword(s):  
Virulence Factors ◽  
Protein Secretion ◽  
Fluorescent Probes ◽  
Imaging Techniques ◽  
Super Resolution ◽  
Bacterial Pathogenesis ◽  
Secretion Systems ◽  
Complex Protein ◽  
Resolution Imaging ◽  
Protein Secretion Systems

ABSTRACT Recent advances in super-resolution imaging techniques, together with new fluorescent probes have enhanced our understanding of bacterial pathogenesis and their interplay within the host. In this review, we provide an overview of what these techniques have taught us about the bacterial lifestyle, the nucleoid organization, its complex protein secretion systems, as well as the secreted virulence factors.

scholarly journals Biohardening of Arabidopsis thaliana Seeds and Seedlings with Fraser Photinia Associated Bacterium (PGB_invit) in In vitro Conditions

2019 ◽  
Vol 47 (3) ◽  
pp. 954-961
Author(s):  
Maria BATOOL ◽  
Özlem AKKAYA ◽  
Mine GÜL ŞEKER ◽  
Yelda ÖZDEN ÇİFTÇİ
Keyword(s):  
Arabidopsis Thaliana ◽  
Photosynthetic Pigments ◽  
Growth Parameters ◽  
Endophytic Bacterium ◽  
Dry Weight ◽  
Bacterial Populations ◽  
Positive Effects ◽  
Inactive Form ◽  
Potential Possibility

The aim of this study was to analyze possible positive effects of putatively endophytic PGPB (PGB_invit), which was isolated from long-term in vitro cultured fraser photinia microshoots, on seed and 7-day old seedling stages of Arabidopsis thaliana. Seeds and in vitro-germinated seedlings were inoculated with 107 CFU/mL and 108 CFU/mL active (A) and inactive (I) endophytic bacterial populations along with their mix compositions (A+I) and suspended in MPYE broth together with their controls (untreated ones). 14 days old seedlings were evaluated for various plant growth parameters [i.e., shoot and root fresh weight (FW), shoot length (SL), shoot and root dry weight (DW), root length (RL) and photosynthetic pigments including chlorophyll a, b and carotenoids of plantlets] as well as endophytic and rhizospheric trait of bacteria. Positive effects of inactive and active bacterium on FW, DW and photosynthetic pigments for 7-day inoculated seedlings were recorded whereas an increase in photosynthetic contents for seed stage inoculations was observed. Rhizospheric and endophytic colonization of the bacteria was confirmed by PCR with the presence of virD1 gene, which is previously recorded to be existed in the plasmid of bacterium after inoculation. Overall, these results demonstrated that this peculiar putative endophytic bacterium being beneficial in active and even more useful in inactive form for A. thaliana when optimum conditions and concentrations are used. Moreover, presence of virD1 gene suggested its potential possibility to be used in bioengineering along with various other beneficial PGPR features as biofertilizer.

scholarly journals Comparison of ATPase-Encoding Type III Secretion System hrcN Genes in Biocontrol Fluorescent Pseudomonads and in Phytopathogenic Proteobacteria

2004 ◽  
Vol 70 (9) ◽  
pp. 5119-5131 ◽  
Author(s):  
Fabio Rezzonico ◽  
Geneviève Défago ◽  
Yvan Moënne-Loccoz
Keyword(s):  
Pseudomonas Syringae ◽  
Protein Secretion ◽  
Type Iii Secretion ◽  
Fluorescent Pseudomonads ◽  
Secretion Systems ◽  
Associated Bacteria ◽  
Type Iii ◽  
Encoding Gene ◽  
Type Iii Protein Secretion ◽  
Protein Secretion Systems

ABSTRACT Type III protein secretion systems play a key role in the virulence of many pathogenic proteobacteria, but they also occur in nonpathogenic, plant-associated bacteria. Certain type III protein secretion genes (e.g., hrcC) have been found in Pseudomonas sp. strain SBW25 (and other biocontrol pseudomonads), but other type III protein secretion genes, such as the ATPase-encoding gene hrcN, have not been found. Using both colony hybridization and a PCR approach, we show here that hrcN is nevertheless present in many biocontrol fluorescent pseudomonads. The phylogeny of biocontrol Pseudomonas strains based on partial hrcN sequences was largely congruent with the phylogenies derived from analyses of rrs (encoding 16S rRNA) and, to a lesser extent, biocontrol genes, such as phlD (for 2,4-diacetylphloroglucinol production) and hcnBC (for HCN production). Most biocontrol pseudomonads clustered separately from phytopathogenic proteobacteria, including pathogenic pseudomonads, in the hrcN tree. The exception was strain KD, which clustered with phytopathogenic pseudomonads, such as Pseudomonas syringae, suggesting that hrcN was acquired from the latter species. Indeed, strain KD (unlike strain SBW25) displayed the same organization of the hrpJ operon, which contains hrcN, as P. syringae. These results indicate that the occurrence of hrcN in most biocontrol pseudomonads is not the result of recent horizontal gene transfer from phytopathogenic bacteria, although such transfer might have occurred for a minority of biocontrol strains.

scholarly journals Microbiota Analysis of an Environmental Slurry and Its Potential Role as a Reservoir of Bovine Digital Dermatitis Pathogens

2017 ◽  
Vol 83 (11) ◽  
Author(s):  
Kirstine Klitgaard ◽  
Mikael L. Strube ◽  
Anastasia Isbrand ◽  
Tim K. Jensen ◽  
Martin W. Nielsen
Keyword(s):  
Dairy Herd ◽  
Amplicon Sequencing ◽  
Dairy Herds ◽  
Rrna Gene ◽  
Digital Dermatitis ◽  
Bacterial Populations ◽  
Associated Bacteria ◽  
Content Type ◽  
Next Generation Sequencing Technology ◽  
Route Of Transmission

ABSTRACT At present, very little information exists regarding what role the environmental slurry may play as an infection reservoir and/or route of transmission for bovine digital dermatitis (DD), a disease which is a global problem in dairy herds. To investigate whether DD-related bacteria belong to the indigenous microbiota of the dairy herd environment, we used deep amplicon sequencing of the 16S rRNA gene in 135 slurry samples collected from different sites in 22 dairy farms, with and without DD-infected cows. Both the general bacterial populations and digital dermatitis-associated Treponema were targeted in this study. The results revealed significant differences in the bacterial communities between the herds, with only 12 bacterial taxa shared across at least 80% of all the individual samples. These differences in the herd microbiota appeared to reflect mainly between-herd variation. Not surprisingly, the slurry was dominated by ubiquitous gastrointestinal bacteria, such as Ruminococcaceae and Lachnospiraceae. Despite the low relative abundance of spirochetes, which ranged from 0 to 0.6%, we were able to detect small amounts of bacterial DNA from DD-associated treponemes in the slurry. However, the DD-associated Treponema spp. were detected only in samples from herds with reported DD problems. These data indicate that treponemes involved in the pathogenesis of DD are not part of the normal environmental microflora in dairy herds without clinical DD and, consequently, that slurry is not a primary reservoir of infection. IMPORTANCE Bovine digital dermatitis (DD), a dermal disease which causes lameness in dairy cattle, is a serious problem worldwide. To control this disease, the infection reservoirs and transmission routes of DD pathogens need to be clarified. The dairy herd slurry may be a pathogen reservoir of DD-associated bacteria. The rationale for the present study was, therefore, to examine whether DD-associated bacteria are always present in slurry or if they are found only in DD-afflicted herds. The results strongly indicated that DD Treponema spp. are not part of the indigenous slurry and, therefore, do not comprise an infection reservoir in healthy herds. This study applied next-generation sequencing technology to decipher the microbial compositions of environmental slurry of dairy herds with and without digital dermatitis.

Sign in / Sign up

Export Citation Format

Share Document