scholarly journals Potential Role of Flavobacterial Gliding-Motility and Type IX Secretion System Complex in Root Colonization and Plant Defense

2014 ◽  
Vol 27 (9) ◽  
pp. 1005-1013 ◽  
Author(s):  
Max Kolton ◽  
Omer Frenkel ◽  
Yigal Elad ◽  
Eddie Cytryn
Keyword(s):  
Plant Defense ◽  
Root Colonization ◽  
Plant Protection ◽  
Plant Root ◽  
Secretion System ◽  
Gliding Motility ◽  
Wild Type ◽  
In Planta ◽  
Clavibacter Michiganensis

Members of the Flavobacterium genus are often highly abundant in the rhizosphere. Nevertheless, the physiological characteristics associated with their enhanced rhizosphere competence are currently an enigma. Flavobacteria possess a unique gliding-motility complex that is tightly associated with a recently characterized Bacteroidetes-specific type IX protein secretion system, which distinguishes them from the rest of the rhizosphere microbiome. We hypothesize that proper functionality of this complex may confer a competitive advantage in the rhizosphere. To test this hypothesis, we constructed mutant and complement root-associated flavobacterial variants with dysfunctional secretion and gliding motility, and tested them in a series of in planta experiments. These mutants demonstrated significantly lower rhizosphere persistence (approximately 10-fold), plant root colonization (approximately fivefold), and seed adhesion capacity (approximately sevenfold) than the wild-type strains. Furthermore, the biocontrol capacity of the mutant strain toward foliar-applied Clavibacter michiganensis was significantly impaired relative to the wild-type strain, suggesting a role of the gliding and secretion complex in plant protection. Collectively, these results provide an initial link between the high abundance of flavobacteria in the rhizosphere and their unique physiology, indicating that the flavobacterial gliding-motility and secretion complex may play a central role in root colonization and plant defense.

Plant Resistance Genes for Fungal Pathogens - Physiological Models and Identification in Cereal Crops

1991 ◽  
Vol 46 (11-12) ◽  
pp. 969-981 ◽  
Author(s):  
Wolfgang Knogge
Keyword(s):  
Plant Defense ◽  
Resistance Genes ◽  
Fungal Pathogens ◽  
Plant Protection ◽  
Defense Responses ◽  
Avirulence Gene ◽  
Physiological Models ◽  
Plant Genes ◽  
Plant Pathogen Interaction

The complex biological phenomenon “resistance” can be reduced to single Mendelian traits acting on both the plant and the pathogen side in a number of pathosystems. According to the “gene-for-gene hypothesis”, the outcome of a plant/pathogen interaction in these cases is incompatibility if a plant carrying a particular resistance gene and a pathogen with the complementary avirulence gene meet. This suggests a causal role of resistance genes in a recognition process initiating active plant defense responses. Fundamentally different strategies are followed to identify these genes molecularly depending on the plant and pathogen species involved. Fungal diseases of crop plants, especially those of cereals, cause dramatic yield losses worldwide. It is assumed that a molecular characterization of plant genes conferring resistance to fungal pathogens will lead to a better understanding of the plant defense system in general permitting the development of new methods of crop plant protection.

scholarly journals The Type IX Secretion System Is Required for Virulence of the Fish Pathogen Flavobacterium columnare

2017 ◽  
Vol 83 (23) ◽  
Author(s):  
Nan Li ◽  
Yongtao Zhu ◽  
Benjamin R. LaFrentz ◽  
Jason P. Evenhuis ◽  
David W. Hunnicutt ◽  
...  
Keyword(s):  
Secretion System ◽  
Gliding Motility ◽  
Control Measures ◽  
Flavobacterium Columnare ◽  
Wild Type ◽  
Secretion Systems ◽  
Content Type ◽  
Freshwater Aquaculture ◽  
Columnaris Disease ◽  
Spent Media

ABSTRACT Flavobacterium columnare, a member of the phylum Bacteroidetes, causes columnaris disease in wild and aquaculture-reared freshwater fish. The mechanisms responsible for columnaris disease are not known. Many members of the phylum Bacteroidetes use type IX secretion systems (T9SSs) to secrete enzymes, adhesins, and proteins involved in gliding motility. The F. columnare genome has all of the genes needed to encode a T9SS. gldN, which encodes a core component of the T9SS, was deleted in wild-type strains of F. columnare. The F. columnare ΔgldN mutants were deficient in the secretion of several extracellular proteins and lacked gliding motility. The ΔgldN mutants exhibited reduced virulence in zebrafish, channel catfish, and rainbow trout, and complementation restored virulence. PorV is required for the secretion of a subset of proteins targeted to the T9SS. An F. columnare ΔporV mutant retained gliding motility but exhibited reduced virulence. Cell-free spent media from exponentially growing cultures of wild-type and complemented strains caused rapid mortality, but spent media from ΔgldN and ΔporV mutants did not, suggesting that soluble toxins are secreted by the T9SS. IMPORTANCE Columnaris disease, caused by F. columnare, is a major problem for freshwater aquaculture. Little is known regarding the virulence factors produced by F. columnare, and control measures are limited. Analysis of targeted gene deletion mutants revealed the importance of the type IX protein secretion system (T9SS) and of secreted toxins in F. columnare virulence. T9SSs are common in members of the phylum Bacteroidetes and likely contribute to the virulence of other animal and human pathogens.

Competitiveness in root colonization by Pseudomonas putida requires the rpoS gene

2001 ◽  
Vol 47 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Charles D Miller ◽  
Young-Cheol Kim ◽  
Anne J Anderson
Keyword(s):  
Pseudomonas Putida ◽  
Culture Medium ◽  
Wild Type Strain ◽  
Root Colonization ◽  
Plant Root ◽  
Wild Type ◽  
Rpos Gene ◽  
Activated Oxygen ◽  
Increased Sensitivity ◽  
Dose Dependent

The rpoS gene in Pseudomonas putida was essential for plant root colonization under competitive conditions from other microbes. The RpoS- mutant survived less well than the wild-type strain in culture medium, and unlike the wild-type, failed to colonize the roots in a peat matrix containing an established diverse microflora. The RpoS-deficient P. putida isolate was generated by insertion of a glucuronidase-npt cassette into the rpoS gene. The RpoS- mutant had dose-dependent increased sensitivity to oxidative stress and produced Mn-superoxide dismutase activity earlier than the parent. While extracts from wild-type P. putida stationary-phase cells contained three isozymes of catalase (CatA, CatB, and CatC), the σ38-deficient P. putida lacked CatB. These results are consistent with previous findings that CatB is induced in stationary-phase.Key words: catalase, starvation, activated oxygen species.

scholarly journals Trichoderma-Plant Root Colonization: Escaping Early Plant Defense Responses and Activation of the Antioxidant Machinery for Saline Stress Tolerance

2013 ◽  
Vol 9 (3) ◽  
pp. e1003221 ◽  
Author(s):  
Yariv Brotman ◽  
Udi Landau ◽  
Álvaro Cuadros-Inostroza ◽  
Tohge Takayuki ◽  
Alisdair R. Fernie ◽  
...  
Keyword(s):  
Plant Defense ◽  
Stress Tolerance ◽  
Root Colonization ◽  
Plant Root ◽  
Defense Responses ◽  
Saline Stress ◽  
Plant Defense Responses ◽  
Antioxidant Machinery

scholarly journals The dgc2 gene encoding di-guanylate cyclase suppresses both motility and biofilm formation in the filamentous cyanobacterium Leptolyngbya boryana.

2022 ◽  
Author(s):  
Kazuma Toida ◽  
Wakana Kushida ◽  
Hiroki Yamamoto ◽  
Kyoka Yamamoto ◽  
Kazuma Uesaka ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Biofilm Formation ◽  
Catalytic Domain ◽  
Genetic Model ◽  
Model Organism ◽  
Gliding Motility ◽  
Spontaneous Mutant ◽  
Filamentous Cyanobacterium ◽  
Wild Type

Colony pattern formations of bacteria with motility manifest complicated morphological self-organization phenomena. Leptolyngbya boryana is the filamentous cyanobacterial species, which has been used as a genetic model organism for studying metabolism including photosynthesis and nitrogen-fixation. Although a widely used type strain (wild type) of this species has not been reported to show any motile activity, we isolated a spontaneous mutant strain which shows active motility (gliding activity) to give rise to complicated colony patters, including comet-like wandering clusters and disk-like rotating vortices on solid media. Whole-genome resequencing identified multiple mutations on the genome in the mutant strain. We confirmed that inactivation of a candidate gene, dgc2 (LBDG_02920), in the wild type background was sufficient to give rise to motility and the morphological colony patterns. This gene encodes a protein, containing the GGDEF motif, which is conserved at the catalytic domain of diguanylate cyclase (DGC). Although DGC has been reported to be involved in biofilm formation, the mutant strain lacking dgc2 significantly facilitated biofilm formation, suggesting a role of DGC for suppressing both gliding motility and biofilm formation. Thus, L. boryana provides an excellent genetic model to study dynamic colony pattern formation, and novel insight on a role of c-di-GMP for biofilm formation.

scholarly journals Disease resistance through impairment of α-SNAP–NSF interaction and vesicular trafficking by soybean Rhg1

2016 ◽  
Vol 113 (47) ◽  
pp. E7375-E7382 ◽  
Author(s):  
Adam M. Bayless ◽  
John M. Smith ◽  
Junqi Song ◽  
Patrick H. McMinn ◽  
Alice Teillet ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Soybean Cyst Nematode ◽  
Protein Complexes ◽  
Essential Gene ◽  
Vesicle Trafficking ◽  
Plant Root ◽  
Wild Type ◽  
In Planta ◽  
Root Cells ◽  
Feeding Site

α-SNAP [soluble NSF (N-ethylmaleimide–sensitive factor) attachment protein] and NSF proteins are conserved across eukaryotes and sustain cellular vesicle trafficking by mediating disassembly and reuse of SNARE protein complexes, which facilitate fusion of vesicles to target membranes. However, certain haplotypes of the Rhg1 (resistance to Heterodera glycines 1) locus of soybean possess multiple repeat copies of an α-SNAP gene (Glyma.18G022500) that encodes atypical amino acids at a highly conserved functional site. These Rhg1 loci mediate resistance to soybean cyst nematode (SCN; H. glycines), the most economically damaging pathogen of soybeans worldwide. Rhg1 is widely used in agriculture, but the mechanisms of Rhg1 disease resistance have remained unclear. In the present study, we found that the resistance-type Rhg1 α-SNAP is defective in interaction with NSF. Elevated in planta expression of resistance-type Rhg1 α-SNAPs depleted the abundance of SNARE-recycling 20S complexes, disrupted vesicle trafficking, induced elevated abundance of NSF, and caused cytotoxicity. Soybean, due to ancient genome duplication events, carries other loci that encode canonical (wild-type) α-SNAPs. Expression of these α-SNAPs counteracted the cytotoxicity of resistance-type Rhg1 α-SNAPs. For successful growth and reproduction, SCN dramatically reprograms a set of plant root cells and must sustain this sedentary feeding site for 2–4 weeks. Immunoblots and electron microscopy immunolocalization revealed that resistance-type α-SNAPs specifically hyperaccumulate relative to wild-type α-SNAPs at the nematode feeding site, promoting the demise of this biotrophic interface. The paradigm of disease resistance through a dysfunctional variant of an essential gene may be applicable to other plant–pathogen interactions.

Dual role of the TYLCV protein V2 in suppressing the host plant defense

2013 ◽  
Author(s):  
Yedidya Gafni ◽  
Moshe Lapidot ◽  
Vitaly Citovsky
Keyword(s):  
Transcription Factor ◽  
Plant Defense ◽  
Host Plant ◽  
Bacterial Infections ◽  
Plant Protection ◽  
Cysteine Proteases ◽  
Host Protein ◽  
Disease Response ◽  
The Way

TYLCV-Is is a major tomato pathogen, causing extensive crop losses in Israel and the U.S. We have identified a TYLCV-Is protein, V2, which acts as a suppressor of RNA silencing. Intriguingly, the counter-defense function of V2 may not be limited to silencing suppression. Our recent data suggest that V2 interacts with the tomato CYP1 protease. CYP1 belongs to the family of papain-like cysteine proteases which participate in programmed cell death (PCD) involved in plant defense against pathogens. Based on these data we proposed a model for dual action of V2 in suppressing the host antiviral defense: V2 targets SGS3 for degradation and V2 inhibits CYP1 activity. To study this we proposed to tackle three specific objectives. I. Characterize the role of V2 in SGS3 proteasomal degradation ubiquitination, II. Study the effects of V2 on CYP1 maturation, enzymatic activity, and accumulation and, III. Analyze the effects of the CYP1-V2 interaction on TYLCV-Is infection. Here we describe results from our study that support our hypothesis: the involvement of the host's innate immune system—in this case, PCD—in plant defense against TYLCV-Is. Also, we use TYLCV-Is to discover the molecular pathway(s) by which this plant virus counters this defense. Towards the end of our study we discovered an interesting involvement of the C2 protein encoded by TYLCV-Is in inducing Hypersensitive Response in N. benthamianaplants which is not the case when the whole viral genome is introduced. This might lead to a better understanding of the multiple processes involved in the way TYLCV is overcoming the defense mechanisms of the host plant cell. In a parallel research supporting the main goal described, we also investigated Agrobacteriumtumefaciens-encoded F-box protein VirF. It has been proposed that VirF targets a host protein for the UPS-mediated degradation, very much the way TYLCV V2 does. In our study, we identified one such interactor, an Arabidopsistrihelix-domain transcription factor VFP3, and further show that its very close homolog VFP5 also interacted with VirF. Interestingly, interactions of VirF with either VFP3 or VFP5 did not activate the host UPS, suggesting that VirF might play other UPS-independent roles in bacterial infection. Another target for VirF is VFP4, a transcription factor that both VirF and its plant functional homolog VBF target to degradation by UPS. Using RNA-seqtranscriptome analysis we showed that VFP4 regulates numerous plant genes involved in disease response, including responses to viral and bacterial infections. Detailed analyses of some of these genes indicated their involvement in plant protection against Agrobacterium infection. Thus, Agrobacterium may facilitate its infection by utilizing the host cell UPS to destabilize transcriptional regulators of the host disease response machinery that limits the infection.

A mutation of a single core gene, tssM, of Type VI secretion system of Xanthomonas perforans influences virulence, epiphytic survival and transmission during pathogenesis on tomato

2021 ◽  
Author(s):  
Prabha Liyanapathiranage ◽  
Jeffrey B Jones ◽  
Neha Potnis
Keyword(s):  
Disease Severity ◽  
Core Gene ◽  
Secretion System ◽  
Wild Type ◽  
In Planta ◽  
Type Vi Secretion System ◽  
Biotrophic Pathogen ◽  
Infection Period ◽  
Xanthomonas Perforans ◽  
Type Vi Secretion

Xanthomonas perforans is a seed-borne hemi-biotrophic pathogen that successfully establishes infection in the phyllosphere of tomato. While the majority of the studies investigating mechanistic basis of pathogenesis have focused on successful apoplastic growth, factors important during asymptomatic colonization in the early stages of disease development are not well understood. In this study, we show that tssM gene of the type VI secretion system cluster i3* (T6SS-i3*) plays a significant role during initial asymptomatic epiphytic colonization at different stages during the life cycle of the pathogen. Mutation in a core gene, tssM of T6SS-i3*, imparted higher aggressiveness to the pathogen, as indicated by higher overall disease severity, higher in planta growth as well as shorter latent infection period compared to the wild-type upon dip-inoculation of 4-5-week-old tomato plants. Contribution of tssM towards aggressiveness was evident during vertical transmission from seed-to-seedling with wild-type showing reduced disease severity as well as lower in planta populations on seedlings compared to the mutant. Presence of functional TssM offered higher epiphytic fitness as well as higher dissemination potential to the pathogen when tested in an experimental setup mimicking transplant house high-humidity conditions. We showed higher osmotolerance being one mechanism by which TssM offers higher epiphytic fitness. Taken together, these data reveal that functional TssM plays a larger role in offering ecological advantage to the pathogen. TssM prolongs the association of hemi-biotrophic pathogen with the host, minimizing overall disease severity, yet facilitating successful dissemination.

scholarly journals The Type IX Secretion System Is Required for Virulence of the Fish Pathogen Flavobacterium psychrophilum

2020 ◽  
Vol 86 (16) ◽  
Author(s):  
Paul Barbier ◽  
Tatiana Rochat ◽  
Haitham H. Mohammed ◽  
Gregory D. Wiens ◽  
Jean-François Bernardet ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Gene Deletion ◽  
Cold Water ◽  
Secretion System ◽  
Gliding Motility ◽  
Control Measures ◽  
Fish Pathogen ◽  
Wild Type ◽  
Content Type ◽  
Bacterial Cold Water Disease

ABSTRACT Flavobacterium psychrophilum causes bacterial cold-water disease in wild and aquaculture-reared fish and is a major problem for salmonid aquaculture. The mechanisms responsible for cold-water disease are not known. It was recently demonstrated that the related fish pathogen, Flavobacterium columnare, requires a functional type IX protein secretion system (T9SS) to cause disease. T9SSs secrete cell surface adhesins, gliding motility proteins, peptidases, and other enzymes, any of which may be virulence factors. The F. psychrophilum genome has genes predicted to encode components of a T9SS. Here, we used a SacB-mediated gene deletion technique recently adapted for use in the Bacteroidetes to delete a core F. psychrophilum T9SS gene, gldN. The ΔgldN mutant cells were deficient for secretion of many proteins in comparison to wild-type cells. Complementation of the mutant with wild-type gldN on a plasmid restored secretion. Compared to wild-type and complemented strains, the ΔgldN mutant was deficient in adhesion, gliding motility, and extracellular proteolytic and hemolytic activities. The ΔgldN mutant exhibited reduced virulence in rainbow trout and complementation restored virulence, suggesting that the T9SS plays an important role in the disease. IMPORTANCE Bacterial cold-water disease, caused by F. psychrophilum, is a major problem for salmonid aquaculture. Little is known regarding the virulence factors involved in this disease, and control measures are inadequate. A targeted gene deletion method was adapted to F. psychrophilum and used to demonstrate the importance of the T9SS in virulence. Proteins secreted by this system are likely virulence factors and targets for the development of control measures.

scholarly journals Role of Extracellular Polysaccharide and Endoglucanase in Root Invasion and Colonization of Tomato Plants by Ralstonia solanacearum

1997 ◽  
Vol 87 (12) ◽  
pp. 1264-1271 ◽  
Author(s):  
Elke Saile ◽  
Jeff A. McGarvey ◽  
Mark A. Schell ◽  
Timothy P. Denny
Keyword(s):  
Ralstonia Solanacearum ◽  
Extracellular Polysaccharide ◽  
Wild Type ◽  
In Planta ◽  
Tomato Plants ◽  
Potted Plants ◽  
Stem Infection ◽  
Soil Infestation ◽  
Plant Stem

Ralstonia solanacearum is a soilborne plant pathogen that normally invades hosts through their roots and then systemically colonizes aerial tissues. Previous research using wounded stem infection found that the major factor in causing wilt symptoms was the high-molecular-mass acidic extracellular polysaccharide (EPS I), but the β-1,4-endoglucanase (EG) also contributes to virulence. We investigated the importance of EPS I and EG for invasion and colonization of tomato by infesting soil of 4-week-old potted plants with either a wild-type derivative or genetically well-defined mutants lacking EPS I, EG, or EPS I and EG. Bacteria of all strains were recovered from surface-disinfested roots and hypocotyls as soon as 4 h after inoculation; that bacteria were present internally was confirmed using immunofluorescence microscopy. However, the EPS-minus mutants did not colonize stems as rapidly as the wild type and the EG-minus mutant. Inoculations of wounded petioles also showed that, even though the mutants multiplied as well as the wild type in planta, EPS-minus strains did not spread as well throughout the plant stem. We conclude that poor colonization of stems by EPS-minus strains after petiole inoculation or soil infestation is due to reduced bacterial movement within plant stem tissues.

Sign in / Sign up

Export Citation Format

Share Document