scholarly journals A newly-evolved chimeric lysin motif receptor-like kinase in Medicago truncatula spp. tricycla R108 extends its Rhizobia symbiotic partnership

2021 ◽  
Author(s):  
Thi-Bich Luu ◽  
Anna Ourth ◽  
Cecile Pouzet ◽  
Nicolas Pauly ◽  
Julie Cullimore
Keyword(s):  
Sinorhizobium Meliloti ◽  
Genetic Basis ◽  
Reverse Genetics ◽  
Acyl Chain ◽  
Receptor Protein ◽  
Nod Factors ◽  
Receptor Like Kinase ◽  
Approaches To Study ◽  
Phenotype Transformation ◽  
Nodulation Specificity

Rhizobial lipochitooligosaccharidic Nod factors, specified by nod genes, are the primary determinants of host specificity in the legume-Rhizobia symbiosis. A Sinorhizobium meliloti nodF/nodL mutant produces Nod factors that differ from wild-type ones in lacking an O-acetate, and with a different acyl chain on the terminal non-reducing sugar. This mutant is defective in nodulation with various Medicago hosts. We examined the nodulation ability of M. truncatula cv Jemalong A17 and M. truncatula ssp. tricycla R108 with the nodF/nodL mutant. We then applied genetic and functional approaches to study the genetic basis and mechanism of nodulation of R108 by this mutant. We show that the nodF/nodL mutant can nodulate R108 but not A17. Using genomics and reverse genetics, we identified a newly-evolved gene in R108, LYK2bis, which is responsible for the phenotype. Transformation with LYK2bis allows A17 to gain nodulation with the nodF/nodL mutant. We found that LYK2bis is involved in specific NF signalling and interacts with the key receptor protein NFP. Our findings reveal that a newly-evolved gene in R108, LYK2bis, extends nodulation specificity to strains producing non-O-acetylated NFs. Interaction between LYK2bis and NFP provides a means of integrating the nodulation signalling pathways.

scholarly journals Natural Variation in Host-Specific Nodulation of Pea Is Associated with a Haplotype of the SYM37 LysM-Type Receptor-Like Kinase

2011 ◽  
Vol 24 (11) ◽  
pp. 1396-1403 ◽  
Author(s):  
Ronghui Li ◽  
Maggie R. Knox ◽  
Anne Edwards ◽  
Bridget Hogg ◽  
T. H. Noel Ellis ◽  
...  
Keyword(s):  
Natural Variation ◽  
Rhizobium Leguminosarum ◽  
Recombinant Inbred Lines ◽  
Acyl Chain ◽  
Introgression Line ◽  
Nod Factors ◽  
Nod Factor ◽  
Group I ◽  
Receptor Like Kinase ◽  
Type Receptor

Rhizobium leguminosarum bv. viciae, which nodulates pea and vetch, makes a mixture of secreted nodulation signals (Nod factors) carrying either a C18:4 or a C18:1 N-linked acyl chain. Mutation of nodE blocks the formation of the C18:4 acyl chain, and nodE mutants, which produce only C18:1-containing Nod factors, are less efficient at nodulating pea. However, there is significant natural variation in the levels of nodulation of different pea cultivars by a nodE mutant of R. leguminosarum bv. viciae. Using recombinant inbred lines from two pea cultivars, one which nodulated relatively well and one very poorly by the nodE mutant, we mapped the nodE-dependent nodulation phenotype to a locus on pea linkage group I. This was close to Sym37 and PsK1, predicted to encode LysM-domain Nod-factor receptor-like proteins; the Sym2 locus that confers Nod-factor-specific nodulation is also in this region. We confirmed the map location using an introgression line carrying this region. Our data indicate that the nodE-dependent nodulation is not determined by the Sym2 locus. We identified several pea lines that are nodulated very poorly by the R. leguminosarum bv. viciae nodE mutant, sequenced the DNA of the predicted LysM-receptor domains of Sym37 and PsK1, and compared the sequences with those derived from pea cultivars that were relatively well nodulated by the nodE mutant. This revealed that one haplotype (encoding six conserved polymorphisms) of Sym37 is associated with very poor nodulation by the nodE mutant. There was no such correlation with polymorphisms at the PsK1 locus. We conclude that the natural variation in nodE-dependent nodulation in pea is most probably determined by the Sym37 haplotype.

scholarly journals Plant evolution driven by interactions with symbiotic and pathogenic microbes

Science ◽  
2021 ◽  
Vol 371 (6531) ◽  
pp. eaba6605 ◽  
Author(s):  
Pierre-Marc Delaux ◽  
Sebastian Schornack
Keyword(s):  
Cell Biology ◽  
Genetic Basis ◽  
Reverse Genetics ◽  
Molecular Mechanisms ◽  
Plant Evolution ◽  
Symbiotic Microorganisms ◽  
Protection Mechanisms ◽  
Evolutionary Trajectories ◽  
Microbe Interactions ◽  
Pathogenic Microbes

During 450 million years of diversification on land, plants and microbes have evolved together. This is reflected in today’s continuum of associations, ranging from parasitism to mutualism. Through phylogenetics, cell biology, and reverse genetics extending beyond flowering plants into bryophytes, scientists have started to unravel the genetic basis and evolutionary trajectories of plant-microbe associations. Protection against pathogens and support of beneficial, symbiotic, microorganisms are sustained by a blend of conserved and clade-specific plant mechanisms evolving at different speeds. We propose that symbiosis consistently emerges from the co-option of protection mechanisms and general cell biology principles. Exploring and harnessing the diversity of molecular mechanisms used in nonflowering plant-microbe interactions may extend the possibilities for engineering symbiosis-competent and pathogen-resilient crops.

scholarly journals Cyclic Di-GMP Regulates Multiple Cellular Functions in the Symbiotic Alphaproteobacterium Sinorhizobium meliloti

2015 ◽  
Vol 198 (3) ◽  
pp. 521-535 ◽  
Author(s):  
Simon Schäper ◽  
Elizaveta Krol ◽  
Dorota Skotnicka ◽  
Volkhard Kaever ◽  
Rolf Hilker ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Sinorhizobium Meliloti ◽  
Acid Stress ◽  
Second Messenger ◽  
Lifestyle Changes ◽  
Single Domain ◽  
Receptor Protein ◽  
Leguminous Plant ◽  
Content Type

ABSTRACTSinorhizobium melilotiundergoes major lifestyle changes between planktonic states, biofilm formation, and symbiosis with leguminous plant hosts. In many bacteria, the second messenger 3′,5′-cyclic di-GMP (c-di-GMP, or cdG) promotes a sessile lifestyle by regulating a plethora of processes involved in biofilm formation, including motility and biosynthesis of exopolysaccharides (EPS). Here, we systematically investigated the role of cdG inS. melilotiRm2011 encoding 22 proteins putatively associated with cdG synthesis, degradation, or binding. Single mutations in 21 of these genes did not cause evident changes in biofilm formation, motility, or EPS biosynthesis. In contrast, manipulation of cdG levels by overproducing endogenous or heterologous diguanylate cyclases (DGCs) or phosphodiesterases (PDEs) affected these processes and accumulation ofN-Acyl-homoserine lactones in the culture supernatant. Specifically, individual overexpression of theS. melilotigenespleD,SMb20523,SMb20447,SMc01464, andSMc03178encoding putative DGCs and ofSMb21517encoding a single-domain PDE protein had an impact and resulted in increased levels of cdG. Compared to the wild type, anS. melilotistrain that did not produce detectable levels of cdG (cdG0) was more sensitive to acid stress. However, it was symbiotically potent, unaffected in motility, and only slightly reduced in biofilm formation. TheSMc01790-SMc01796locus, homologous to theAgrobacterium tumefaciensuppABCDEFcluster governing biosynthesis of a unipolarly localized polysaccharide, was found to be required for cdG-stimulated biofilm formation, while the single-domain PilZ protein McrA was identified as a cdG receptor protein involved in regulation of motility.IMPORTANCEWe present the first systematic genome-wide investigation of the role of 3′,5′-cyclic di-GMP (c-di-GMP, or cdG) in regulation of motility, biosynthesis of exopolysaccharides, biofilm formation, quorum sensing, and symbiosis in a symbiotic alpha-rhizobial species. Phenotypes of anS. melilotistrain unable to produce cdG (cdG0) demonstrated that this second messenger is not essential for root nodule symbiosis but may contribute to acid tolerance. Our data further suggest that enhanced levels of cdG promote sessility ofS. melilotiand uncovered a single-domain PilZ protein as regulator of motility.

scholarly journals Genetic Basis and Physiological Effects of Lipid A Hydroxylation in Pseudomonas aeruginosa PAO1

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 291 ◽  
Author(s):  
Alessandra Lo Sciuto ◽  
Matteo Cervoni ◽  
Roberta Stefanelli ◽  
Maria Concetta Spinnato ◽  
Alessandra Di Giamberardino ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Human Blood ◽  
Genetic Basis ◽  
Lipid A ◽  
Acyl Chain ◽  
Membrane Integrity ◽  
Physiological Role ◽  
Infection Model ◽  
Acyl Chains

Modifications of the lipid A moiety of lipopolysaccharide influence the physicochemical properties of the outer membrane of Gram-negative bacteria. Some bacteria produce lipid A with a single hydroxylated secondary acyl chain. This hydroxylation is catalyzed by the dioxygenase LpxO, and is important for resistance to cationic antimicrobial peptides (e.g., polymyxins), survival in human blood, and pathogenicity in animal models. The lipid A of the human pathogen Pseudomonas aeruginosa can be hydroxylated in both secondary acyl chains, but the genetic basis and physiological role of these hydroxylations are still unknown. Through the generation of single and double deletion mutants in the lpxO1 and lpxO2 homologs of P. aeruginosa PAO1 and lipid A analysis by mass spectrometry, we demonstrate that both LpxO1 and LpxO2 are responsible for lipid A hydroxylation, likely acting on different secondary acyl chains. Lipid A hydroxylation does not appear to affect in vitro growth, cell wall stability, and resistance to human blood or antibiotics in P. aeruginosa. In contrast, it is required for infectivity in the Galleria mellonella infection model, without relevantly affecting in vivo persistence. Overall, these findings suggest a role for lipid A hydroxylation in P. aeruginosa virulence that could not be directly related to outer membrane integrity.

scholarly journals Identification and Characterization of a nodH Ortholog from the Alfalfa-Nodulating Or191-Like Rhizobia

2007 ◽  
Vol 20 (2) ◽  
pp. 138-145 ◽  
Author(s):  
M. F. Del Papa ◽  
M. Pistorio ◽  
W. O. Draghi ◽  
M. J. Lozano ◽  
M. A. Giusti ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Single Copy ◽  
Nod Factors ◽  
Distinctive Features ◽  
Genetic Mosaic ◽  
Strict Requirement ◽  
Identification And Characterization ◽  
Local Synteny ◽  
Marked Specificity

Nodulation of Medicago sativa (alfalfa) is known to be restricted to Sinorhizobium meliloti and a few other rhizobia that include the poorly characterized isolates related to Rhizobium sp. strain Or191. Distinctive features of the symbiosis between alfalfa and S. meliloti are the marked specificity from the plant to the bacteria and the strict requirement for the presence of sulfated lipochitooligosac-charides (Nod factors [NFs]) at its reducing end. Here, we present evidence of the presence of a functional nodH-encoded NF sulfotransferase in the Or191-like rhizobia. The nodH gene, present in single copy, maps to a high molecular weight megaplasmid. As in S. meliloti, a nodF homolog was identified immediately upstream of nodH that was transcribed in the opposite direction (local synteny). This novel nodH ortholog was cloned and shown to restore both NF sulfation and the Nif+Fix+ phenotypes when introduced into an S. meliloti nodH mutant. Unexpectedly, however, nodH disruption in the Or191-like bacteria did not abolish their ability to nodulate alfalfa, resulting instead in a severely delayed nodulation. In agreement with evidence from other authors, the nodH sequence analysis strongly supports the idea that the Or191-like rhizobia most likely represent a genetic mosaic resulting from the horizontal transfer of symbiotic genes from a sinorhizobial megaplas-mid to a not yet clearly identified ancestor.

scholarly journals High-Affinity Nod Factor Binding Site from Phaseolus vulgaris Cell Suspension Cultures

2002 ◽  
Vol 15 (8) ◽  
pp. 834-839 ◽  
Author(s):  
Frédéric Gressent ◽  
Natacha Mantegazza ◽  
Julie V. Cullimore ◽  
Hugues Driguez ◽  
Raoul Ranjeva ◽  
...  
Keyword(s):  
Phaseolus Vulgaris ◽  
Binding Site ◽  
Acyl Chain ◽  
Minor Role ◽  
Nod Factors ◽  
Nod Factor ◽  
Factor Binding Site ◽  
Factor Binding ◽  
High Affinity ◽  
Perception System

The lipo-chitooligosaccharidic Nod factors produced by rhizobia are key molecules in the establishment of symbiosis with legumes and probably are recognized by the host plant via specific receptors. Here, we report on the presence of a binding site in cell cultures of Phaseolus vulgaris displaying a high affinity for Nod factors from Rhizobium tropici (NodRt-V) (Me, S, C18:1), a symbiont of this legume. The binding site shares common properties with NFBS2, a Nod-factor binding site previously characterised in Medicago varia, in terms of affinity, preferential plasma-membrane location, and sensitivity to proteases and lysine reactive reagents. However, the bean site poorly recognizes the Nod factors produced by Sinorhizobium meliloti, the symbiont of Medicago. The study of selectivity toward the Nod factors reveals that the length and degree of unsaturation of the acyl chain and the length of the oligosaccharidic moiety are important determinants of high affinity binding to the bean site; whereas, the N-methyl and O-sulfuryl groups play a minor role. Thus, the common characteristics of P. vulgaris and M. varia Nod-factor binding sites suggest that they probably correspond to structurally related proteins, but their different selectivity suggests that they may be involved in a differential perception system for Nod factors in legumes.

scholarly journals Genetic Organization of the Region Encoding Regulation, Biosynthesis, and Transport of Rhizobactin 1021, a Siderophore Produced by Sinorhizobium meliloti

2001 ◽  
Vol 183 (8) ◽  
pp. 2576-2585 ◽  
Author(s):  
Damien Lynch ◽  
John O'Brien ◽  
Timothy Welch ◽  
Paul Clarke ◽  
Páraic ÓCuı́v ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Membrane Receptor ◽  
Receptor Protein ◽  
Outer Membrane Receptor ◽  
Phenotypic Analysis ◽  
Reverse Transcription Pcr ◽  
Transposon Insertion ◽  
Transposon Insertions

ABSTRACT Eight genes have been identified that function in the regulation, biosynthesis, and transport of rhizobactin 1021, a hydroxamate siderophore produced under iron stress bySinorhizobium meliloti. The genes were sequenced, and transposon insertion mutants were constructed for phenotypic analysis. Six of the genes, named rhbABCDEF, function in the biosynthesis of the siderophore and were shown to constitute an operon that is repressed under iron-replete conditions. Another gene in the cluster, named rhtA, encodes the outer membrane receptor protein for rhizobactin 1021. It was shown to be regulated by iron and to encode a product having 61% similarity to IutA, the outer membrane receptor for aerobactin. Transcription of both therhbABCDEF operon and the rhtA gene was found to be positively regulated by the product of the eighth gene in the cluster, named rhrA, which has characteristics of an AraC-type transcriptional activator. The six genes in therhbABCDEF operon have interesting gene junctions with short base overlaps existing between the genes. Similarities between the protein products of the biosynthesis genes and other proteins suggest that rhizobactin 1021 is synthesized by the formation of a novel siderophore precursor, 1,3-diaminopropane, which is then modified and attached to citrate in steps resembling those of the aerobactin biosynthetic pathway. The cluster of genes is located on the pSyma megaplasmid of S. meliloti 2011. Reverse transcription-PCR with RNA isolated from mature alfalfa nodules yielded no products for rhbF or rhtA at a time when the nifH gene was strongly expressed, indicating that siderophore biosynthesis and transport genes are not strongly expressed when nitrogenase is being formed in root nodules. Mutants having transposon insertions in the biosynthesis or transport genes induced effective nitrogen-fixing nodules on alfalfa plants.

scholarly journals Nonspecific Symbiosis Between Sophora flavescens and Different Rhizobia

2018 ◽  
Vol 31 (2) ◽  
pp. 224-232 ◽  
Author(s):  
Yuan Hui Liu ◽  
Yin Shan Jiao ◽  
Li Xue Liu ◽  
Dan Wang ◽  
Chang Fu Tian ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Host Specificity ◽  
Genetic Basis ◽  
Negative Regulator ◽  
Related Gene ◽  
Nod Factors ◽  
Wild Type ◽  
Sophora Flavescens ◽  
Tn5 Mutants ◽  
The Impact

We explored the genetic basis of the promiscuous symbiosis of Sophora flavescens with diverse rhizobia. To determine the impact of Nod factors (NFs) on the symbiosis of S. flavescens, nodulation-related gene mutants of representative rhizobial strains were generated. Strains with mutations in common nodulation genes (nodC, nodM, and nodE) failed to nodulate S. flavescens, indicating that the promiscuous nodulation of this plant is strictly dependent on the basic NF structure. Mutations of the NF decoration genes nodH, nodS, nodZ, and noeI did not affect the nodulation of S. flavescens, but these mutations affected the nitrogen-fixation efficiency of nodules. Wild-type Bradyrhizobium diazoefficiens USDA110 cannot nodulate S. flavescens, but we obtained 14 Tn5 mutants of B. diazoefficiens that nodulated S. flavescens. This suggested that the mutations had disrupted a negative regulator that prevents nodulation of S. flavescens, leading to nonspecific nodulation. For Ensifer fredii CCBAU 45436 mutants, the minimal NF structure was sufficient for nodulation of soybean and S. flavescens. In summary, the mechanism of promiscuous symbiosis of S. flavescens with rhizobia might be related to its nonspecific recognition of NF structures, and the host specificity of rhizobia may also be controlled by currently unknown nodulation-related genes.

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