Regulation of Burkholderia cenocepacia virulence by the fatty acyl-CoA ligase DsfR as a response regulator of quorum sensing signal.

Quorum sensing (QS) is a cell-to-cell communication mechanism mediated by small diffusible signaling molecules. Previous studies showed that RpfR controls Burkholderia cenocepacia virulence as a cis-2-dodecenoic acid (BDSF) QS signal receptor. Here, we report that the fatty acyl-CoA ligase DsfR (BCAM2136), which efficiently catalyzes in vitro synthesis of lauryl-CoA and oleoyl-CoA from lauric acid and oleic acid, respectively, acts as a global transcriptional regulator to control B.

Phytopathogenic bacteria utilize host glucose as a signal to stimulate virulence through LuxR homologues.

Chemical signal-mediated biological communication is common within bacteria and between bacteria and their hosts. Many plant-associated bacteria respond to unknown plant compounds to regulate bacterial gene expression. However, the nature of the plant compounds that mediate such interkingdom communication and the underlying mechanisms remain poorly characterized.

Type III Secretion System Repressor RhpR Induces GrlP, a Glycine-Rich Outer Membrane Lipoprotein with Functions in Regulating the Periplasmic Space and Pleiotropic Responses.

The two-component system RhpRS was initially identified as a regulator of genes encoding the type III secretion system (T3SS) in Pseudomonas syringae. Phosphorylated RhpR (P-RhpR) negatively regulates the T3SS genes by repressing the promoter, but directly activates the expression of a small gene named here as . Here, we show that is expressed higher in rich medium than in minimal medium in pv.

-3-Oxo-Octanoyl Homoserine Lactone Primes Plant Resistance Against Necrotrophic Pathogen by Coordinating Jasmonic Acid and Auxin-Signaling Pathways.

Many Gram-negative bacteria use small signal molecules, such as -acyl-homoserine lactones (AHLs), to communicate with each other and coordinate their collective behaviors. Recently, increasing evidence has demonstrated that long-chained quorum-sensing signals play roles in priming defense responses in plants. Our previous work indicated that a short-chained signal, -3-oxo-octanoyl homoserine lactone (3OC8-HSL), enhanced Arabidopsis resistance to the hemi-biotrophic bacteria pv.

RIR1 represses plant immunity by interacting with mitochondrial complex I subunit in rice.

We previously observed decreased expression of rice OsmiR159a.1 on infection with the bacterial blight-causing pathogen Xanthomonas oryzae pv. oryzae (Xoo), and identified the OsLRR_RLK (leucine-rich repeat_ receptor like kinase) gene as an authentic target of OsmiR159a.

Whole genome sequencing of Enterobacter mori, an emerging pathogen of kiwifruit and the potential genetic adaptation to pathogenic lifestyle.

Members of the Enterobacter genus are gram-negative bacteria, which are used as plant growth-promoting bacteria, and increasingly recovered from economic plants as emerging pathogens. A new Enterobacter mori strain, designated CX01, was isolated as an emerging bacterial pathogen of a recent outbreak of kiwifruit canker-like disease in China. The main symptoms associated with this syndrome are bleeding cankers on the trunk and branch, and brown leaf spots.

5S Multifunctional Intelligent Coating with Superdurable, Superhydrophobic, Self-Monitoring, Self-Heating, and Self-Healing Properties for Existing Construction Application.

There is a constant drive to develop ultra-high-performance multifunctional coatings for existing construction used in modern engineering technologies. For these materials to be used in unsound infrastructure protections, they are required to present enhanced robustness while bearing functionalities to meet multiple uses. Single-function coating is not smart enough to provide satisfactory protection, and the preparation process of multifunctional materials is complex, costly, and provides poor durability.

Two components of the rhpPC operon coordinately regulate the type III secretion system and bacterial fitness in Pseudomonas savastanoi pv. phaseolicola.

Many plant bacterial pathogens including Pseudomonas species, utilize the type III secretion system (T3SS) to deliver effector proteins into plant cells. Genes encoding the T3SS and its effectors are repressed in nutrient-rich media but are rapidly induced after the bacteria enter a plant or are transferred into nutrient-deficient media. To understand how the T3SS genes are regulated, we screened for P.

Xanthomonas campestris Promotes Diffusible Signal Factor Biosynthesis and Pathogenicity by Utilizing Glucose and Sucrose from Host Plants.

The plant pathogen Xanthomonas campestris pv. campestris produces diffusible signal factor (DSF) quorum sensing (QS) signals to regulate its biological functions and virulence. Our previous study showed that X.

A dual role for proline iminopeptidase in the regulation of bacterial motility and host immunity.

During plant-pathogen interactions, pathogenic bacteria have evolved multiple strategies to cope with the sophisticated defence systems of host plants. Proline iminopeptidase (PIP) is essential to Xanthomonas campestris pv. campestris (Xcc) virulence, and is conserved in many plant-associated bacteria, but its pathogenic mechanism remains unclear.

integrates -2-dodecenoic acid and cyclic dimeric guanosine monophosphate signals to control virulence.

Quorum sensing (QS) signals are used by bacteria to regulate biological functions in response to cell population densities. Cyclic diguanosine monophosphate (c-di-GMP) regulates cell functions in response to diverse environmental chemical and physical signals that bacteria perceive. In , the QS signal receptor RpfR degrades intracellular c-di-GMP when it senses the QS signal -2-dodecenoic acid, also called diffusible signal factor (BDSF), as a proxy for high cell density.

[Function of biofilms in phytopathogenic bacterial-host interactions].

Biofilms are complex three-dimensional bacterial assemblages that attach to biotic or abiotic solid surfaces, and frequently embed within a self-produced matrix of extracellular polymeric substances. Biofilm formation is a microbial defense response to biotic and abiotic stresses, and a key factor for survival in adverse environments. A wide variety of microorganisms can colonize distant tissues of higher plants, such as leaves, vascular network and roots, and adhere to the surface of the tissues to form biofilms.

Interkingdom signaling in plant-microbe interactions.

The widespread communications between prokaryotes and eukaryotes via signaling molecules are believed to affect gene expression in both partners. During the communication process, the contacted organisms produce and release small molecules that establish communication channels between two kingdoms-this procedure is known as interkingdom signaling. Interkingdom communications are widespread between pathogenic or beneficial bacteria and their host plants, with diversified outcomes depending on the specific chemical-triggered signaling pathways.

Dynamic and Coordinated Expression Changes of Rice Small RNAs in Response to Xanthomonas oryzae pv. oryzae.

Endogenous small RNAs are newly identified players in plant immune responses, yet their roles in rice (Oryza sativa) responding to pathogens are still less understood, especially for pathogens that can cause severe yield losses. We examined the small RNA expression profiles of rice leaves at 2, 6, 12, and 24 hours post infection of Xanthomonas oryzae pv. oryzae (Xoo) virulent strain PXO99, the causal agent of rice bacterial blight disease.

[Efficient transient expression to analyze miRNA targets in rice protoplasts].

Compared with the transgenic approach, transient assays provide a convenient alternative to analyze gene expression. To analyze the relationship between miRNAs and their target genes, a rice protoplast system to detect target gene activity was established. The MIRNA and GFP-fused target sequence (or GFP-fused mutated sequence as a non-target control) were constructed into the same plasmid, and then delivered into rice protoplasts.

Synergistic activation of the pathogenicity-related proline iminopeptidase gene in Xanthomonas campestris pv. campestris by HrpX and a LuxR homolog.

Xanthomonas campestris pv. campestris strain 8004 contains an orphan quorum-sensing (QS) locus, xccR-pip(Xcc), in which the proline iminopeptidase (pip(Xcc)) gene (where "Xcc" indicates that the pip gene is from X. campestris pv.

[Implication of post-translational modifications in suppressor activity and stability of the Cucumber mosaic virus 2b protein].

To gain insights into the function of potential post-translational modifications on the activity of the Cucumber mosaic virus (CMV)-encoded silencing suppressor protein 2b, one predicted phosphorylation site (S40) and two predicted ubiquitination/sumoylation sites (K22 and K39) in CMV-Q2b protein were individually or simultaneously mutated by site-directed mutagenesis methods. These Q2b mutants were inserted into plant expression vectors, expressed in plant leaves, and then analyzed for their silencing suppressor activities. The results showed that S40A mutation greatly impaired both the local and systemic silencing suppressor activity, and the K22R mutation has no significant effect on the suppressor activity, while the K22R/K39R double mutation reduced the systemic silencing suppressor activity.

XerR, a negative regulator of XccR in Xanthomonas campestris pv. campestris, relieves its repressor function in planta.

We previously reported that XccR, a LuxR-type regulator of Xanthomonas campestris pv. campestris (Xcc), activates the downstream proline iminopeptidase virulence gene (pip) in response to certain host plant factor(s). In this report, we further show that the expression of the xccR gene was repressed in the culture medium by an NtrC-type response regulator, which we named XerR (XccR expression-related, repressor), and that this repression was relieved when the bacteria were grown in planta.

Identification and functional characterization of small non-coding RNAs in Xanthomonas oryzae pathovar oryzae.

Background: Small non-coding RNAs (sRNAs) are regarded as important regulators in prokaryotes and play essential roles in diverse cellular processes. Xanthomonas oryzae pathovar oryzae (Xoo) is an important plant pathogenic bacterium which causes serious bacterial blight of rice. However, little is known about the number, genomic distribution and biological functions of sRNAs in Xoo.

3-Acetonyl-3-hydroxyoxindole: a new inducer of systemic acquired resistance in plants.

Systemic acquired resistance (SAR) is an inducible defence mechanism which plays a central role in protecting plants from microbial pathogen attack. Guided by bioassays, a new chemical inducer of SAR was isolated from the extracts of Strobilanthes cusia and identified to be 3-acetonyl-3-hydroxyoxindole (AHO), a derivative of isatin. Tobacco plants treated with AHO exhibited enhanced resistance to tobacco mosaic virus (TMV) and to the fungal pathogen Erysiphe cichoracearum (powdery mildew), accompanied by increased levels of pathogenesis-related gene 1 (PR-1) expression, salicylic acid (SA) accumulation and phenylalanine ammonia-lyase activity.

A proline iminopeptidase gene upregulated in planta by a LuxR homologue is essential for pathogenicity of Xanthomonas campestris pv. campestris.

Expression of bacterial genes is often regulated by complex mechanisms, some of which involve host cues. Analysis of the Xanthomonas campestris pv. campestris (Xcc) genome sequence revealed the presence of an xccR/pip locus.

Comparative and functional genomic analyses of the pathogenicity of phytopathogen Xanthomonas campestris pv. campestris.

Xanthomonas campestris pathovar campestris (Xcc) is the causative agent of crucifer black rot disease, which causes severe losses in agricultural yield world-wide. This bacterium is a model organism for studying plant-bacteria interactions. We sequenced the complete genome of Xcc 8004 (5,148,708 bp), which is highly conserved relative to that of Xcc ATCC 33913.