The rhizobial type III effectors ErnA and Sup3 hijack the SUMOylation pathway to trigger nodule formation in Aeschynomene species.

Rhizobial type III effectors (T3Es) play a crucial role in the symbiotic relationship between rhizobia and legumes by manipulating host cellular processes to promote nodule formation. Previously, we identified two T3Es, ErnA and Sup3, that trigger nodulation in Aeschynomene spp. in the absence of Nod factors.

Development and characterization of a saturated transposon mutant library of serovar Enteritidis LA5.

We created and characterized a saturated Tn-seq mutant library in subsp. ser. Enteritidis strain LA5.

Taxonomic distribution of SbmA/BacA and BacA-like antimicrobial peptide transporters suggests independent recruitment and convergent evolution in host-microbe interactions.

Antimicrobial peptides (AMPs) are often produced by eukaryotes to control bacterial populations in both pathogenic and mutualistic symbioses. Several pathogens and nitrogen-fixing legume symbionts depend on transporters called SbmA (or BacA) or BclA (BacA-like) to survive exposure to AMPs. However, how broadly these transporters are distributed amongst bacteria, and their evolutionary history, is poorly understood.

Quantifying Bacterial Chemotaxis in Controlled and Stationary Chemical Gradients with a Microfluidic Device.

Chemotaxis refers to the ability of organisms to detect chemical gradients and bias their motion accordingly. Quantifying this bias is critical for many applications and requires a device that can generate and maintain a constant concentration field over a long period allowing for the observation of bacterial responses. In 2010, a method was introduced that combines microfluidics and hydrogel to facilitate the diffusion of chemical species and to set a linear gradient in a bacterial suspension in the absence of liquid flow.

FcrX coordinates cell cycle and division during free-living growth and symbiosis by a ClpXP-dependent mechanism.

is a soil bacterium that establishes a nitrogen-fixing symbiosis within root nodules of legumes. In this symbiosis, undergoes a drastic cellular change leading to a terminally differentiated form, called bacteroid, characterized by genome endoreduplication, increased cell size, and high membrane permeability. Bacterial cell cycle (mis)regulation is at the heart of this differentiation process.

Pathogenic nematodes exploit Achilles' heel of plant symbioses.

Cyst nematode parasites disrupt beneficial associations of crops with rhizobia and mycorrhiza. Chen et al. discovered the mechanism and demonstrated that the soybean cyst nematode Heterodera glycines secretes a chitinase that destroys key symbiotic signals from the microbial symbionts.

Ingested soil bacteria breach gut epithelia and prime systemic immunity in an insect.

Insects lack acquired immunity and were thought to have no immune memory, but recent studies reported a phenomenon called immune priming, wherein sublethal dose of pathogens or nonpathogenic microbes stimulates immunity and prevents subsequential pathogen infection. Although the evidence for insect immune priming is accumulating, the underlying mechanisms are still unclear. The bean bug acquires its gut microbiota from ambient soil and spatially structures them into a multispecies and variable community in the anterior midgut and a specific, monospecies symbiont population in the posterior region.

Transposon sequencing reveals the essential gene set and genes enabling gut symbiosis in the insect symbiont .

is a bacterium belonging to the genus , which is able to colonize multiple environments like soils and the gut of the bean bug . We constructed a saturated mariner transposon library and revealed by transposon-sequencing that 498 protein-coding genes constitute the essential genome of for growth in free-living conditions. By comparing essential gene sets of and seven related strains, only 120 common genes were identified, indicating that a large part of the essential genome is strain-specific.

Widespread Bradyrhizobium distribution of diverse Type III effectors that trigger legume nodulation in the absence of Nod factor.

The establishment of the rhizobium-legume symbiosis is generally based on plant perception of Nod factors (NFs) synthesized by the bacteria. However, some Bradyrhizobium strains can nodulate certain legume species, such as Aeschynomene spp. or Glycine max, independently of NFs, and via two different processes that are distinguished by the necessity or not of a type III secretion system (T3SS).

Dual-Uptake Mode of the Antibiotic Phazolicin Prevents Resistance Acquisition by Gram-Negative Bacteria.

Phazolicin (PHZ) is a peptide antibiotic exhibiting narrow-spectrum activity against rhizobia closely related to its producer, sp. strain Pop5. Here, we show that the frequency of spontaneous PHZ-resistant mutants in Sinorhizobium meliloti is below the detection limit.

Symbiont coordinates stem cell proliferation, apoptosis, and morphogenesis of gut symbiotic organ in the stinkbug- symbiosis.

The bean bug obtains a specific bacterial symbiont, (), from the environmental soil and harbors it in the posterior midgut region that is composed of hundreds of crypts. While newly hatched aposymbiotic insects possess primordial midgut crypts with little or no lumen, colonization of triggers swift development of the symbiotic organ, forming enlarged and opened crypts, and the symbiont subsequently fills the luminal cavities of those mature crypts. The cellular processes of crypt development triggered by colonization are poorly understood.

Complete Genome Sequences of Two Strains Producing Azol(in)e-Modified Antibiotics.

Rhizobia are known for their ability to establish symbiotic relationships with plants. The specialized metabolism of these bacteria remains understudied. Here, we report whole-genome sequences of two rhizobia producing narrow-spectrum antirhizobial azol(in)e-modified peptides: that of sp.

Intercontinental Diversity of Caballeronia Gut Symbionts in the Conifer Pest Bug Leptoglossus occidentalis.

Many stinkbugs in the superfamily Coreoidea (Hemiptera: Heteroptera) develop crypts in the posterior midgut, harboring Caballeronia (Burkholderia) symbionts. These symbionts form a monophyletic group in Burkholderia sensu lato, called the "stinkbug-associated beneficial and environmental (SBE)" group, recently reclassified as the new genus Caballeronia. SBE symbionts are separated into the subclades SBE-α and SBE-β.

Differential Genetic Strategies of Burkholderia vietnamiensis and Paraburkholderia kururiensis for Root Colonization of Oryza sativa subsp. and O. sativa subsp. , as Revealed by Transposon Mutagenesis Sequencing.

Burkholderia vietnamiensis LMG10929 and Paraburkholderia kururiensis M130 are bacterial rice growth-promoting models. Besides this common ecological niche, species of the genus are also found as opportunistic human pathogens, while species are mostly environmental and plant associated. In this study, we compared the genetic strategies used by B.

DNA Methylation in Species during Free-Living Growth and during Nitrogen-Fixing Symbiosis with spp.

Methylation of specific DNA sequences is ubiquitous in bacteria and has known roles in immunity and regulation of cellular processes, such as the cell cycle. Here, we explored DNA methylation in bacteria of the genus , including its potential role in regulating terminal differentiation during nitrogen-fixing symbiosis with legumes. Using single-molecule real-time sequencing, six genome-wide methylated motifs were identified across four strains, five of which were strain-specific.

The Type III Effectome of the Symbiotic Strain ORS3257.

Many strains are able to establish a Nod factor-independent symbiosis with the leguminous plant by the use of a type III secretion system (T3SS). Recently, an important advance in the understanding of the molecular factors supporting this symbiosis has been achieved by the in silico identification and functional characterization of 27 putative T3SS effectors (T3Es) of ORS3257. In the present study, we experimentally extend this catalog of T3Es by using a multi-omics approach.

Sinorhizobium meliloti Functions Required for Resistance to Antimicrobial NCR Peptides and Bacteroid Differentiation.

Legumes of the genus have a symbiotic relationship with the bacterium Sinorhizobium meliloti and develop root nodules housing large numbers of intracellular symbionts. Members of the odule-specific ysteine-ich peptide (NCR) family induce the endosymbionts into a terminal differentiated state. Individual cationic NCRs are antimicrobial peptides that have the capacity to kill the symbiont, but the nodule cell environment prevents killing.

Bradyrhizobium diazoefficiens USDA110 Nodulation of Aeschynomene afraspera Is Associated with Atypical Terminal Bacteroid Differentiation and Suboptimal Symbiotic Efficiency.

Legume plants can form root organs called nodules where they house intracellular symbiotic rhizobium bacteria. Within nodule cells, rhizobia differentiate into bacteroids, which fix nitrogen for the benefit of the plant. Depending on the combination of host plants and rhizobial strains, the output of rhizobium-legume interactions varies from nonfixing associations to symbioses that are highly beneficial for the plant.

Dual oxidase enables insect gut symbiosis by mediating respiratory network formation.

Most animals harbor a gut microbiota that consists of potentially pathogenic, commensal, and mutualistic microorganisms. Dual oxidase (Duox) is a well described enzyme involved in gut mucosal immunity by the production of reactive oxygen species (ROS) that antagonizes pathogenic bacteria and maintains gut homeostasis in insects. However, despite its nonspecific harmful activity on microorganisms, little is known about the role of Duox in the maintenance of mutualistic gut symbionts.

Thioesterase-mediated side chain transesterification generates potent Gq signaling inhibitor FR900359.

The potent and selective Gq protein inhibitor depsipeptide FR900359 (FR), originally discovered as the product of an uncultivable plant endosymbiont, is synthesized by a complex biosynthetic system comprising two nonribosomal peptide synthetase (NRPS) assembly lines. Here we characterize a cultivable bacterial FR producer, enabling detailed investigations into biosynthesis and attachment of the functionally important FR side chain. We reconstitute side chain assembly by the monomodular NRPS FrsA and the non-heme monooxygenase FrsH, and characterize intermolecular side chain transesterification to the final macrocyclic intermediate FR-Core, mediated by the FrsA thioesterase domain.

A Peptidoglycan Amidase Mutant of Burkholderia insecticola Adapts an L-form-like Shape in the Gut Symbiotic Organ of the Bean Bug Riptortus pedestris.

Bacterial cell shapes may be altered by the cell cycle, nutrient availability, environmental stress, and interactions with other organisms. The bean bug Riptortus pedestris possesses a symbiotic bacterium, Burkholderia insecticola, in its midgut crypts. This symbiont is a typical rod-shaped bacterium under in vitro culture conditions, but changes to a spherical shape inside the gut symbiotic organ of the host insect, suggesting the induction of morphological alterations in B.

Unexplored Arsenals of Legume Peptides With Potential for Their Applications in Medicine and Agriculture.

During endosymbiosis, bacteria live intracellularly in the symbiotic organ of their host. The host controls the proliferation of endosymbionts and prevents their spread to other tissues and organs. In Rhizobium-legume symbiosis the major host effectors are secreted nodule-specific cysteine-rich (NCR) peptides, produced exclusively in the symbiotic cells.

Burkholderia insecticola triggers midgut closure in the bean bug Riptortus pedestris to prevent secondary bacterial infections of midgut crypts.

In addition to abiotic triggers, biotic factors such as microbial symbionts can alter development of multicellular organisms. Symbiont-mediated morphogenesis is well-investigated in plants and marine invertebrates but rarely in insects despite the enormous diversity of insect-microbe symbioses. The bean bug Riptortus pedestris is associated with Burkholderia insecticola which are acquired from the environmental soil and housed in midgut crypts.