301
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Barrett LG, Broadhurst LM, Thrall PH. Geographic adaptation in plant-soil mutualisms: tests using Acacia spp. and rhizobial bacteria. Funct Ecol 2011. [DOI: 10.1111/j.1365-2435.2011.01940.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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302
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Li R, Knox MR, Edwards A, Hogg B, Ellis THN, Wei G, Downie JA. Natural variation in host-specific nodulation of pea is associated with a haplotype of the SYM37 LysM-type receptor-like kinase. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:1396-403. [PMID: 21995800 DOI: 10.1094/mpmi-01-11-0004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
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.
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Affiliation(s)
- Ronghui Li
- Northwest A & F University, Yangling, China
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303
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Zhang L, Chen XJ, Lu HB, Xie ZP, Staehelin C. Functional analysis of the type 3 effector nodulation outer protein L (NopL) from Rhizobium sp. NGR234: symbiotic effects, phosphorylation, and interference with mitogen-activated protein kinase signaling. J Biol Chem 2011; 286:32178-87. [PMID: 21775427 PMCID: PMC3173237 DOI: 10.1074/jbc.m111.265942] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 06/30/2011] [Indexed: 12/31/2022] Open
Abstract
Pathogenic bacteria use type 3 secretion systems to deliver virulence factors (type 3 effector proteins) directly into eukaryotic host cells. Similarly, type 3 effectors of certain nitrogen-fixing rhizobial strains affect nodule formation in the symbiosis with host legumes. Nodulation outer protein L (NopL) of Rhizobium sp. strain NGR234 is a Rhizobium-specific type 3 effector. Nodulation tests and microscopic analysis showed that distinct necrotic areas were rapidly formed in ineffective nodules of Phaseolus vulgaris (cv. Tendergreen) induced by strain NGRΩnopL (NGR234 mutated in nopL), indicating that NopL antagonized nodule senescence. Further experiments revealed that NopL interfered with mitogen-activated protein kinase (MAPK) signaling in yeast and plant cells (Nicotiana tabacum). Expression of nopL in yeast disrupted the mating pheromone (α-factor) response pathway, whereas nopL expression in N. tabacum suppressed cell death induced either by overexpression of the MAPK gene SIPK (salicylic acid-induced protein kinase) or by SIPK(DD) (mutation in the TXY motif resulting in constitutive MAPK activity). These data indicate that NopL impaired function of MAPK proteins or MAPK substrates. Furthermore, we demonstrate that NopL was multiply phosphorylated either in yeast or N. tabacum cells that expressed nopL. Four phosphorylated serines were confirmed by mass spectrometry. All four phosphorylation sites exhibit a Ser-Pro pattern, a typical motif in MAPK substrates. Taken together, data suggest that NopL mimics a MAPK substrate and that NopL suppresses premature nodule senescence by impairing MAPK signaling in host cells.
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Affiliation(s)
- Ling Zhang
- From the State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Xue-Jiao Chen
- From the State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Huang-Bin Lu
- From the State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Zhi-Ping Xie
- From the State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Christian Staehelin
- From the State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
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304
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Nodulation-gene-inducing flavonoids increase overall production of autoinducers and expression of N-acyl homoserine lactone synthesis genes in rhizobia. Res Microbiol 2011; 162:715-23. [DOI: 10.1016/j.resmic.2011.05.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Accepted: 04/16/2011] [Indexed: 11/20/2022]
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305
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Ibáñez F, Fabra A. Rhizobial Nod factors are required for cortical cell division in the nodule morphogenetic programme of the Aeschynomeneae legume Arachis. PLANT BIOLOGY (STUTTGART, GERMANY) 2011; 13:794-800. [PMID: 21815984 DOI: 10.1111/j.1438-8677.2010.00439.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Nod factors are among the best-studied molecules implicated in the signal exchange that leads to legume-rhizobia symbiosis. The role of these molecules in symbiosis development has been primarily studied in legumes invaded through infection threads. In these plants, Nod factors generate several responses required for nodulation, including the induction of cortical cell division to form the nodule primordium. Arachis hypogaea L. (peanut) exhibits a specific mode of rhizobial infection and nodule morphogenetic programme in which infection threads are never formed. The role of Nod factors in this particular mechanism is unknown. In this work, a peanut symbiont mutant strain unable to produce Nod factors was obtained and characterised. The strain Bradyrhizobium (Arachis) sp. SEMIA 6144 V2 is altered in the nodC gene, which encodes an N-acetylglucosaminyl transferase involved in the first step of the Nod factor biosynthetic pathway. Further research revealed that, although its ability to colonise peanut roots was unaffected, it is not capable of inducing the division of cortical cells. The results obtained indicate that rhizobial Nod factors are essential for the induction of cortical cell division that leads to nodule primordium formation.
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Affiliation(s)
- F Ibáñez
- Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
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306
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Kucho KI, Hay AE, Normand P. The determinants of the actinorhizal symbiosis. Microbes Environ 2011; 25:241-52. [PMID: 21576879 DOI: 10.1264/jsme2.me10143] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The actinorhizal symbiosis is a major contributor to the global nitrogen budget, playing a dominant role in ecological successions following disturbances. The mechanisms involved are still poorly known but there emerges the vision that on the plant side, the kinases that transmit the symbiotic signal are conserved with those involved in the transmission of the Rhizobium Nod signal in legumes. However, on the microbial side, complementation with Frankia DNA of Rhizobium nod mutants failed to permit identification of symbiotic genes. Furthermore, analysis of three Frankia genomes failed to permit identification of canonical nod genes and revealed symbiosis-associated genes such as nif, hup, suf and shc to be spread around the genomes. The present review explores some recently published approaches aimed at identifying bacterial symbiotic determinants.
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Affiliation(s)
- Ken-Ichi Kucho
- Department of Chemistry and Bioscience, Graduate School of Science and Engineering, Kagoshima UniversityKorimoto1–21–35, Kagoshima 890–0065, Japan
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307
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Rodríguez-Echeverría S, Le Roux JJ, Crisóstomo JA, Ndlovu J. Jack-of-all-trades and master of many? How does associated rhizobial diversity influence the colonization success of Australian Acacia species? DIVERS DISTRIB 2011. [DOI: 10.1111/j.1472-4642.2011.00787.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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308
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First genomic analysis of the broad-host-range Rhizobium sp. LPU83 strain, a member of the low-genetic diversity Oregon-like Rhizobium sp. group. J Biotechnol 2011; 155:3-10. [DOI: 10.1016/j.jbiotec.2011.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 12/22/2010] [Accepted: 01/13/2011] [Indexed: 11/20/2022]
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309
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Ventorino V, Caputo R, De Pascale S, Fagnano M, Pepe O, Moschetti G. Response to salinity stress of Rhizobium leguminosarum bv. viciae strains in the presence of different legume host plants. ANN MICROBIOL 2011. [DOI: 10.1007/s13213-011-0322-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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310
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Isolation, phylogeny and evolution of the SymRK gene in the legume genus Lupinus L. Mol Phylogenet Evol 2011; 60:49-61. [DOI: 10.1016/j.ympev.2011.04.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 04/18/2011] [Accepted: 04/19/2011] [Indexed: 02/04/2023]
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311
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Fumeaux C, Bakkou N, Kopcińska J, Golinowski W, Westenberg DJ, Müller P, Perret X. Functional analysis of the nifQdctA1y4vGHIJ operon of Sinorhizobium fredii strain NGR234 using a transposon with a NifA-dependent read-out promoter. MICROBIOLOGY-SGM 2011; 157:2745-2758. [PMID: 21719545 DOI: 10.1099/mic.0.049999-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Rhizobia are a disparate collection of soil bacteria capable of reducing atmospheric nitrogen in symbiosis with legumes (Fix phenotype). Synthesis of the nitrogenase and its accessory components is under the transcriptional control of the key regulator NifA and is generally restricted to the endosymbiotic forms of rhizobia known as bacteroids. Amongst studied rhizobia, Sinorhizobium fredii strain NGR234 has the remarkable ability to fix nitrogen in association with more than 130 species in 73 legume genera that form either determinate, indeterminate or aeschynomenoid nodules. Hence, NGR234 is a model organism to study nitrogen fixation in association with a variety of legumes. The symbiotic plasmid pSfrNGR234a carries more than 50 genes that are under the transcriptional control of NifA. To facilitate the functional analysis of NifA-regulated genes a new transposable element, TnEKm-PwA, was constructed. This transposon combines the advantages of in vitro mutagenesis of cloned DNA fragments with a conditional read-out promoter from NGR234 (PwA) that reinitiates NifA-dependent transcription downstream of transposition sites. To test the characteristics of the new transposon, the nifQdctA1y4vGHIJ operon was mutated using either the Omega interposon or TnEKm-PwA. The symbiotic phenotypes on various hosts as well as the transcriptional characteristics of these mutants were analysed in detail and compared with the ineffective (Fix(-)) phenotype of strain NGRΔnifA, which lacks a functional copy of nifA. De novo transcription from inserted copies of TnEKm-PwA inside bacteroids was confirmed by qRT-PCR. Unexpectedly, polar mutants in dctA1 and nifQ were Fix(+) on all of the hosts tested, indicating that none of the six genes of the nifQ operon of NGR234 is essential for symbiotic nitrogen fixation on plants that form nodules of either determinate or indeterminate types.
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Affiliation(s)
- Coralie Fumeaux
- University of Geneva, Sciences III, Department of Botany and Plant Biology, Microbiology Unit, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Nadia Bakkou
- University of Geneva, Sciences III, Department of Botany and Plant Biology, Microbiology Unit, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Joanna Kopcińska
- Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, ul. Nowoursynowska 159, 02-776 Warsaw, Poland
| | - Wladyslav Golinowski
- Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, ul. Nowoursynowska 159, 02-776 Warsaw, Poland
| | - David J Westenberg
- Department of Biological Sciences, Missouri University of Science and Technology, 105A Schrenk Hall, 400 West 11th Street, Rolla, 65409-1120 MO, USA
| | - Peter Müller
- Fachbereich Biologie/Zellbiologie, Philipps Universität Marburg, Karl-von-Frisch-Str. 8, 35032 Marburg, Germany
| | - Xavier Perret
- University of Geneva, Sciences III, Department of Botany and Plant Biology, Microbiology Unit, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
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312
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Mazur A, Stasiak G, Wielbo J, Kubik-Komar A, Marek-Kozaczuk M, Skorupska A. Intragenomic diversity of Rhizobium leguminosarum bv. trifolii clover nodule isolates. BMC Microbiol 2011; 11:123. [PMID: 21619713 PMCID: PMC3123555 DOI: 10.1186/1471-2180-11-123] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 05/30/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Soil bacteria from the genus Rhizobium are characterized by a complex genomic architecture comprising chromosome and large plasmids. Genes responsible for symbiotic interactions with legumes are usually located on one of the plasmids, named the symbiotic plasmid (pSym). The plasmids have a great impact not only on the metabolic potential of rhizobia but also underlie genome rearrangements and plasticity. RESULTS Here, we analyzed the distribution and sequence variability of markers located on chromosomes and extrachromosomal replicons of Rhizobium leguminosarum bv. trifolii strains originating from nodules of clover grown in the same site in cultivated soil. First, on the basis of sequence similarity of repA and repC replication genes to the respective counterparts of chromids reported in R. leguminosarum bv. viciae 3841 and R. etli CFN42, chromid-like replicons were distinguished from the pool of plasmids of the nodule isolates studied. Next, variability of the gene content was analyzed in the different genome compartments, i.e., the chromosome, chromid-like and 'other plasmids'. The stable and unstable chromosomal and plasmid genes were detected on the basis of hybridization data. Displacement of a few unstable genes between the chromosome, chromid-like and 'other plasmids', as well as loss of some markers was observed in the sampled strains. Analyses of chosen gene sequences allowed estimation of the degree of their adaptation to the three genome compartments as well as to the host. CONCLUSIONS Our results showed that differences in distribution and sequence divergence of plasmid and chromosomal genes can be detected even within a small group of clover nodule isolates recovered from clovers grown at the same site. Substantial divergence of genome organization could be detected especially taking into account the content of extrachromosomal DNA. Despite the high variability concerning the number and size of plasmids among the studied strains, conservation of the location as well as dynamic distribution of the individual genes (especially replication genes) of a particular genome compartment were demonstrated. The sequence divergence of particular genes may be affected by their location in the given genome compartment. The 'other plasmid' genes are less adapted to the host genome than the chromosome and chromid-like genes.
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Affiliation(s)
- Andrzej Mazur
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
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313
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Population genomics of Sinorhizobium medicae based on low-coverage sequencing of sympatric isolates. ISME JOURNAL 2011; 5:1722-34. [PMID: 21562597 DOI: 10.1038/ismej.2011.55] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We investigated the genomic diversity of a local population of the symbiotic bacterium Sinorhizobium medicae, isolated from the roots of wild Medicago lupulina plants, in order to assess genomic diversity, to identify genomic regions influenced by duplication, deletion or strong selection, and to explore the composition of the pan-genome. Partial genome sequences of 12 isolates were obtained by Roche 454 shotgun sequencing (average 5.3 Mb per isolate) and compared with the published sequence of S. medicae WSM 419. Homologous recombination appears to have less impact on the polymorphism patterns of the chromosome than on the chromid pSMED01 and megaplasmid pSMED02. Moreover, pSMED02 is a hot spot of insertions and deletions. The whole chromosome is characterized by low sequence polymorphism, consistent with the high density of housekeeping genes. Similarly, the level of polymorphism of symbiosis genes (low) and of genes involved in polysaccharide synthesis (high) may reflect different selection. Finally, some isolates carry genes that may confer adaptations that S. medicae WSM 419 lacks, including homologues of genes encoding rhizobitoxine synthesis, iron uptake, response to autoinducer-2, and synthesis of distinct polysaccharides. The presence or absence of these genes was confirmed by PCR in each of these 12 isolates and a further 27 isolates from the same population. All isolates had rhizobitoxine genes, while the other genes were co-distributed, suggesting that they may be on the same mobile element. These results are discussed in relation to the ecology of Medicago symbionts and in the perspective of population genomics studies.
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314
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Degefu T, Wolde-meskel E, Frostegård Å. Multilocus sequence analyses reveal several unnamed Mesorhizobium genospecies nodulating Acacia species and Sesbania sesban trees in Southern regions of Ethiopia. Syst Appl Microbiol 2011; 34:216-26. [DOI: 10.1016/j.syapm.2010.09.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 08/14/2010] [Accepted: 09/28/2010] [Indexed: 11/17/2022]
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315
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Specific developmental window for establishment of an insect-microbe gut symbiosis. Appl Environ Microbiol 2011; 77:4075-81. [PMID: 21531836 DOI: 10.1128/aem.00358-11] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The alydid stinkbug Riptortus pedestris is specifically associated with a beneficial Burkholderia symbiont in the midgut crypts. Exceptional among insect-microbe mutualistic associations, the Burkholderia symbiont is not vertically transmitted but orally acquired by nymphal insects from the environment every generation. Here we experimentally investigated the process of symbiont acquisition during the nymphal development of R. pedestris. In a field population, many 2nd instar nymphs were Burkholderia free, while all 3rd, 4th, and 5th instar nymphs were infected. When reared on soil-grown potted soybean plants, Burkholderia acquisition occurred at a drastically higher frequency in the 2nd instar than in the other instars. Oral administration of cultured Burkholderia cells showed that 2nd and 3rd instar nymphs are significantly more susceptible to the symbiont infection than 1st, 4th, and 5th instar nymphs. Histological observations revealed rudimentary midgut crypts in the 1st instar, in contrast to well-developed midgut crypts in the 2nd and later instars. These results indicate that R. pedestris acquires the Burkholderia symbiont from the environment mainly during the 2nd instar period and strongly suggest that the competence for the symbiont infection is developmentally regulated by the host side. Potential mechanisms involved in infection competence and possible reasons why the infection preferentially occurs in the 2nd instar are discussed.
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316
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Saeki K. Rhizobial measures to evade host defense strategies and endogenous threats to persistent symbiotic nitrogen fixation: a focus on two legume-rhizobium model systems. Cell Mol Life Sci 2011; 68:1327-39. [PMID: 21365276 PMCID: PMC11114668 DOI: 10.1007/s00018-011-0650-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Revised: 02/15/2011] [Accepted: 02/15/2011] [Indexed: 10/18/2022]
Abstract
The establishment and maintenance of rhizobium-legume symbioses require a sequence of highly regulated and coordinated events between the organisms. Although the interaction is mutually beneficial under nitrogen-limited conditions, it can resemble a pathogenic infection at some stages. Some host legumes mount defense reactions, including the production of reactive oxygen species (ROS) and defensin-like antimicrobial compounds. To subvert these host defenses, the infecting rhizobial cells can use measures to passively protect themselves and actively modulate host functions. This review first describes the establishment and maintenance of active nodules, as well as the external and endogenous attack and threat stages. Next, recent studies of ROS scavenging enzymes, the BacA protein originally found in Sinorhizobium meliloti, and the type III/IV secretion systems are discussed, with a focus on two legume-rhizobium model systems.
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Affiliation(s)
- Kazuhiko Saeki
- Department of Biological Sciences, Faculty of Science, Nara Women's University, Kitauoya Nishimachi, Nara, Japan.
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317
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Staehelin C, Xie ZP, Illana A, Vierheilig H. Long-distance transport of signals during symbiosis: are nodule formation and mycorrhization autoregulated in a similar way? PLANT SIGNALING & BEHAVIOR 2011; 6:372-7. [PMID: 21455020 PMCID: PMC3142418 DOI: 10.4161/psb.6.3.13881] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 10/07/2010] [Indexed: 05/03/2023]
Abstract
Legumes enter nodule symbioses with nitrogen-fixing bacteria (rhizobia), whereas most flowering plants establish symbiotic associations with arbuscular mycorrhizal (AM) fungi. Once first steps of symbiosis are initiated, nodule formation and mycorrhization in legumes is negatively controlled by a shoot-derived inhibitor (SDI), a phenomenon termed autoregulation. According to current views, autoregulation of nodulation and mycorrhization in legumes is regulated in a similar way. CLE peptides induced in response to rhizobial nodulation signals (Nod factors) have been proposed to represent the ascending long-distance signals to the shoot. Although not proven yet, these CLE peptides are likely perceived by leucine-rich repeat (LRR) autoregulation receptor kinases in the shoot. Autoregulation of mycorrhization in non-legumes is reminiscent to the phenomenon of "systemic acquired resistance" in plant-pathogen interactions.
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Affiliation(s)
- Christian Staehelin
- State Key Laboratory of Biocontrol; School of Life Sciences; Sun Yat-sen (Zhongshan) University (East Campus); Guangzhou, China
| | - Zhi-Ping Xie
- State Key Laboratory of Biocontrol; School of Life Sciences; Sun Yat-sen (Zhongshan) University (East Campus); Guangzhou, China
| | - Antonio Illana
- Departamento de Microbiología de Suelos; Estación Experimental del Zaidín; CSIC; Granada, Spain
| | - Horst Vierheilig
- Departamento de Microbiología de Suelos; Estación Experimental del Zaidín; CSIC; Granada, Spain
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318
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Stark JL, Mercier KA, Mueller GA, Acton TB, Xiao R, Montelione GT, Powers R. Solution structure and function of YndB, an AHSA1 protein from Bacillus subtilis. Proteins 2011; 78:3328-40. [PMID: 20818668 DOI: 10.1002/prot.22840] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The solution structure of the Bacillus subtilis protein YndB has been solved using NMR to investigate proposed biological functions. The YndB structure exhibits the helix-grip fold, which consists of a β-sheet with two small and one long α-helix, forming a hydrophobic cavity that preferentially binds lipid-like molecules. Sequence and structure comparisons with proteins from eukaryotes, prokaryotes, and archaea suggest that YndB is very similar to the eukaryote protein Aha1, which binds to the middle domain of Hsp90 and induces ATPase activity. On the basis of these similarities, YndB has been classified as a member of the activator of Hsp90 ATPase homolog 1-like protein (AHSA1) family with a function that appears to be related to stress response. An in silico screen of a compound library of ∼ 18,500 lipids was used to identify classes of lipids that preferentially bind YndB. The in silico screen identified, in order of affinity, the chalcone/hydroxychalcone, flavanone, and flavone/flavonol classes of lipids, which was further verified by 2D (1) H-(15) N HSQC NMR titration experiments with trans-chalcone, flavanone, flavone, and flavonol. All of these compounds are typically found in plants as precursors to various flavonoid antibiotics and signaling molecules. The sum of the data suggests an involvement of YndB with the stress response of B. subtilis to chalcone-like flavonoids released by plants due to a pathogen infection. The observed binding of chalcone-like molecules by YndB is likely related to the symbiotic relationship between B. subtilis and plants.
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Affiliation(s)
- Jaime L Stark
- Department of Chemistry, University of Nebraska Lincoln, Lincoln, Nebraska 68588-0304, USA
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319
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Naringenin regulates expression of genes involved in cell wall synthesis in Herbaspirillum seropedicae. Appl Environ Microbiol 2011; 77:2180-3. [PMID: 21257805 DOI: 10.1128/aem.02071-10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Five thousand mutants of Herbaspirillum seropedicae SmR1 carrying random insertions of transposon pTnMod-OGmKmlacZ were screened for differential expression of LacZ in the presence of naringenin. Among the 16 mutants whose expression was regulated by naringenin were genes predicted to be involved in the synthesis of exopolysaccharides, lipopolysaccharides, and auxin. These loci are probably involved in establishing interactions with host plants.
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320
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Zanetti ME, Blanco FA, Beker MP, Battaglia M, Aguilar OM. A C subunit of the plant nuclear factor NF-Y required for rhizobial infection and nodule development affects partner selection in the common bean-Rhizobium etli symbiosis. THE PLANT CELL 2010; 22:4142-57. [PMID: 21139064 PMCID: PMC3027164 DOI: 10.1105/tpc.110.079137] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 11/03/2010] [Accepted: 11/12/2010] [Indexed: 05/20/2023]
Abstract
Legume plants are able to interact symbiotically with soil bacteria to form nitrogen-fixing root nodules. Although specific recognition between rhizobia and legume species has been extensively characterized, plant molecular determinants that govern the preferential colonization by different strains within a single rhizobium species have received little attention. We found that the C subunit of the heterotrimeric nuclear factor NF-Y from common bean (Phaseolus vulgaris) NF-YC1 plays a key role in the improved nodulation seen by more efficient strains of rhizobia. Reduction of NF-YC1 transcript levels by RNA interference (RNAi) in Agrobacterium rhizogenes-induced hairy roots leads to the arrest of nodule development and defects in the infection process with either high or low efficiency strains. Induction of three G2/M transition cell cycle genes in response to rhizobia was impaired or attenuated in NF-YC1 RNAi roots, suggesting that this transcription factor might promote nodule development by activating cortical cell divisions. Furthermore, overexpression of this gene has a positive impact on nodulation efficiency and selection of Rhizobium etli strains that are naturally less efficient and bad competitors. Our findings suggest that this transcription factor might be part of a mechanism that links nodule organogenesis with an early molecular dialogue that selectively discriminates between high- and low-quality symbiotic partners, which holds important implications for optimizing legume performance.
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321
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Bonaldi K, Gherbi H, Franche C, Bastien G, Fardoux J, Barker D, Giraud E, Cartieaux F. The Nod factor-independent symbiotic signaling pathway: development of Agrobacterium rhizogenes-mediated transformation for the legume Aeschynomene indica. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1537-44. [PMID: 21039272 DOI: 10.1094/mpmi-06-10-0137] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The nitrogen-fixing symbiosis between Aeschynomene indica and photosynthetic bradyrhizobia is the only legume-rhizobium association described to date that does not require lipochito-oligosaccharide Nod factors (NF). To assist in deciphering the molecular basis of this NF-independent interaction, we have developed a protocol for Agrobacterium rhizogenes-mediated transformation of A. indica. The cotransformation frequency (79%), the nodulation efficiency of transgenic roots (90%), and the expression pattern of the 35S Cauliflower mosaic virus promoter in transgenic nodules were all comparable to those obtained for model legumes. We have made use of this tool to monitor the heterologous spatio-temporal expression of the pMtENOD11-β-glucuronidase fusion, a widely used molecular reporter for rhizobial infection and nodulation in both legumes and actinorhizal plants. While MtENOD11 promoter activation was not observed in A. indica roots prior to nodulation, strong reporter-gene expression was observed in the invaded cells of young nodules and in the cell layers bordering the central zone of older nodules. We conclude that pMtENOD11 expression can be used as an infection-related marker in A. indica and that Agrobacterium rhizogenes-mediated root transformation of Aeschynomene spp. will be an invaluable tool for determining the molecular basis of the NF-independent symbiosis.
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Affiliation(s)
- Katia Bonaldi
- IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR IRD/SupAgro/INRA/UM2/CIRAD, F-34398 Montpellier, France
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322
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Khaosaad T, Staehelin C, Steinkellner S, Hage-Ahmed K, Ocampo JA, Garcia-Garrido JM, Vierheilig H. The Rhizobium sp. strain NGR234 systemically suppresses arbuscular mycorrhizal root colonization in a split-root system of barley (Hordeum vulgare). PHYSIOLOGIA PLANTARUM 2010; 140:238-45. [PMID: 20618761 DOI: 10.1111/j.1399-3054.2010.01396.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Nitrogen-fixing bacteria (rhizobia) form a nodule symbiosis with legumes, but also induce certain effects on non-host plants. Here, we used a split-root system of barley to examine whether inoculation with Rhizobium sp. strain NGR234 on one side of a split-root system systemically affects arbuscular mycorrhizal (AM) root colonization on the other side. Mutant strains of NGR234 deficient in Nod factor production (strain NGRΔnodABC), perception of flavonoids (strain NGRΔnodD1) and secretion of type 3 effector proteins (strain NGRΩrhcN) were included in this study. Inoculation resulted in a systemic reduction of AM root colonization with all tested strains. However, the suppressive effect of strain NGRΩrhcN was less pronounced. Moreover, levels of salicylic acid, an endogenous molecule related to plant defense, were increased in roots challenged with rhizobia. These data indicate that barley roots perceived NGR234 and that a systemic regulatory mechanism of AM root colonization was activated. The suppressive effect appears to be Nod factor independent, but enhanced by type 3 effector proteins of NGR234.
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Affiliation(s)
- Thanasan Khaosaad
- Faculty of Sciences, Department of Biotechnology, Ramkhamhaeng University, Bangkok 10240, Thailand
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323
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Yang S, Tang F, Gao M, Krishnan HB, Zhu H. R gene-controlled host specificity in the legume-rhizobia symbiosis. Proc Natl Acad Sci U S A 2010; 107:18735-40. [PMID: 20937853 PMCID: PMC2973005 DOI: 10.1073/pnas.1011957107] [Citation(s) in RCA: 193] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Leguminous plants can enter into root nodule symbioses with nitrogen-fixing soil bacteria known as rhizobia. An intriguing but still poorly understood property of the symbiosis is its host specificity, which is controlled at multiple levels involving both rhizobial and host genes. It is widely believed that the host specificity is determined by specific recognition of bacterially derived Nod factors by the cognate host receptor(s). Here we describe the positional cloning of two soybean genes Rj2 and Rfg1 that restrict nodulation with specific strains of Bradyrhizobium japonicum and Sinorhizobium fredii, respectively. We show that Rj2 and Rfg1 are allelic genes encoding a member of the Toll-interleukin receptor/nucleotide-binding site/leucine-rich repeat (TIR-NBS-LRR) class of plant resistance (R) proteins. The involvement of host R genes in the control of genotype-specific infection and nodulation reveals a common recognition mechanism underlying symbiotic and pathogenic host-bacteria interactions and suggests the existence of their cognate avirulence genes derived from rhizobia. This study suggests that establishment of a root nodule symbiosis requires the evasion of plant immune responses triggered by rhizobial effectors.
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Affiliation(s)
- Shengming Yang
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546
| | - Fang Tang
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546
- College of Bioengineering, Chongqing University, Chongqing 400044, China; and
| | - Muqiang Gao
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546
| | - Hari B. Krishnan
- US Department of Agriculture–Agricultural Research Service and Division of Plant Sciences, University of Missouri, Columbia, MO 65211
| | - Hongyan Zhu
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546
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324
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The nodulation of alfalfa by the acid-tolerant Rhizobium sp. strain LPU83 does not require sulfated forms of lipochitooligosaccharide nodulation signals. J Bacteriol 2010; 193:30-9. [PMID: 20971905 DOI: 10.1128/jb.01009-10] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The induction of root nodules by the majority of rhizobia has a strict requirement for the secretion of symbiosis-specific lipochitooligosaccharides (nodulation factors [NFs]). The nature of the chemical substitution on the NFs depends on the particular rhizobium and contributes to the host specificity imparted by the NFs. We present here a description of the genetic organization of the nod gene cluster and the characterization of the chemical structure of the NFs associated with the broad-host-range Rhizobium sp. strain LPU83, a bacterium capable of nodulating at least alfalfa, bean, and Leucena leucocephala. The nod gene cluster was located on the plasmid pLPU83b. The organization of the cluster showed synteny with those of the alfalfa-nodulating rhizobia, Sinorhizobium meliloti and Sinorhizobium medicae. Interestingly, the strongest sequence similarity observed was between the partial nod sequences of Rhizobium mongolense USDA 1844 and the corresponding LPU83 nod genes sequences. The phylogenetic analysis of the intergenic region nodEG positions strain LPU83 and the type strain R. mongolense 1844 in the same branch, which indicates that Rhizobium sp. strain LPU83 might represent an early alfalfa-nodulating genotype. The NF chemical structures obtained for the wild-type strain consist of a trimeric, tetrameric, and pentameric chitin backbone that shares some substitutions with both alfalfa- and bean-nodulating rhizobia. Remarkably, while in strain LPU83 most of the NFs were sulfated in their reducing terminal residue, none of the NFs isolated from the nodH mutant LPU83-H were sulfated. The evidence obtained supports the notion that the sulfate decoration of NFs in LPU83 is not necessary for alfalfa nodulation.
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325
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Fabra A, Castro S, Taurian T, Angelini J, Ibañez F, Dardanelli M, Tonelli M, Bianucci E, Valetti L. Interaction among Arachis hypogaea L. (peanut) and beneficial soil microorganisms: how much is it known? Crit Rev Microbiol 2010; 36:179-94. [PMID: 20214416 DOI: 10.3109/10408410903584863] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The leguminous crop Arachis hypogaea L. (peanut) is originally from South America and then was disseminated to tropical and subtropical regions. The dissemination of the crop resulted in peanut plants establishing a symbiotic nitrogen-fixing relationship with a wide diversity of indigenous soil bacteria. We present in this review, advances on the molecular basis for the crack-entry infection process involved in the peanut-rhizobia interaction, the diversity of rhizobial and fungal antagonistic bacteria associated with peanut plants, the effect of abiotic and biotic stresses on this interaction and the response of peanut to inoculation.
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Affiliation(s)
- A Fabra
- Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina
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326
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Kikuchi Y, Hosokawa T, Fukatsu T. An ancient but promiscuous host-symbiont association between Burkholderia gut symbionts and their heteropteran hosts. ISME JOURNAL 2010; 5:446-60. [PMID: 20882057 DOI: 10.1038/ismej.2010.150] [Citation(s) in RCA: 184] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Here, we investigated 124 stinkbug species representing 20 families and 5 superfamilies for their Burkholderia gut symbionts, of which 39 species representing 6 families of the superfamilies Lygaeoidea and Coreoidea were Burkholderia-positive. Diagnostic PCR surveys revealed high frequencies of Burkholderia infection in natural populations of the stinkbugs, and substantial absence of vertical transmission of Burkholderia infection to their eggs. In situ hybridization confirmed localization of the Burkholderia in their midgut crypts. In the lygaeoid and coreoid stinkbugs, development of midgut crypts in their alimentary tract was coincident with the Burkholderia infection, suggesting that the specialized morphological configuration is pivotal for establishment and maintenance of the symbiotic association. The Burkholderia symbionts were easily isolated as pure culture on standard microbiological media, indicating the ability of the gut symbionts to survive outside the host insects. Molecular phylogenetic analysis showed that the gut symbionts of the lygaeoid and coreoid stinkbugs belong to a β-proteobacterial clade together with Burkholderia isolates from soil environments and Burkholderia species that induce plant galls. On the phylogeny, the stinkbug-associated, environmental and gall-forming Burkholderia strains did not form coherent groups, indicating host-symbiont promiscuity among these stinkbugs. Symbiont culturing revealed that slightly different Burkholderia genotypes often coexist in the same insects, which is also suggestive of host-symbiont promiscuity. All these results strongly suggest an ancient but promiscuous host-symbiont relationship between the lygaeoid/coreoid stinkbugs and the Burkholderia gut symbionts. Possible mechanisms as to how the environmentally transmitted promiscuous symbiotic association has been stably maintained in the evolutionary course are discussed.
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Affiliation(s)
- Yoshitomo Kikuchi
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Hokkaido Center, Sapporo, Japan.
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327
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John RP, Tyagi R, Brar S, Surampalli R, Prévost D. Bio-encapsulation of microbial cells for targeted agricultural delivery. Crit Rev Biotechnol 2010; 31:211-26. [DOI: 10.3109/07388551.2010.513327] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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328
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Plasmids of the Rhizobiaceae and Their Role in Interbacterial and Transkingdom Interactions. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/978-3-642-14512-4_12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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329
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Maruya J, Saeki K. The bacA gene homolog, mlr7400, in Mesorhizobium loti MAFF303099 is dispensable for symbiosis with Lotus japonicus but partially capable of supporting the symbiotic function of bacA in Sinorhizobium meliloti. PLANT & CELL PHYSIOLOGY 2010; 51:1443-52. [PMID: 20668224 DOI: 10.1093/pcp/pcq114] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Establishment of rhizobium-legume symbiosis requires a series of mutual authentication, which might involve bacterial evasion of host defense. One such evasion-related genes is Sinorhizobium meliloti bacA that is essential for bacteroid formation. BacA is a transmembrane protein highly similar to Escherichia coli SbmA, a predicted transporter, and has homologs even in animal pathogens, such as Brucella abortus in which the homolog contributes to effective survival in host macrophages. Despite such a significance in host-microbe interactions, studies on rhizobial BacA have been mostly performed with the Medicago-Sinorhizobium model system that forms indeterminate cylindrical nodules. Since Lotus japonicus-Mesorhizobium loti constitutes another model system that forms determinate globular nodules, we genetically analyzed the bacA homolog with the locus tag mlr7400 in M. loti MAFF303099. We found that the mlr7400-null mutant ML7400DK was able to establish quasi-healthy symbiosis with the Lotus plant with 50-80% nitrogen-fixing capacity. This dispensability for symbiosis was in contrast to the indispensability of S. meliloti BacA for symbiosis. However, free-living phenotypes of ML7400DK paralleled those of known bacA mutants, i.e. ML7400DK showed decreased sensitivity to the antibiotics bleomycin and gentamicin as well as increased sensitivity to membrane-disturbing reagents such as SDS. Conservation of the free-living function between Mlr7400 protein and S. meliloti BacA was further confirmed by heterologous complementation experiments. Although simple introduction of mlr7400 into the S. meliloti bacA mutant did not increase the symbiotic capacity at all, a significant but marginal increase was obtained when mlr7400 was fused to the S. meliloti bacA promoter. These findings might indicate currently progressing evolutionary specialization among BacA-SbmA proteins.
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Affiliation(s)
- Jumpei Maruya
- Department of Biological Sciences, Faculty of Science, Nara Women's University, Nara 850-6503, Japan
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330
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Bhattacharya A, Sood P, Citovsky V. The roles of plant phenolics in defence and communication during Agrobacterium and Rhizobium infection. MOLECULAR PLANT PATHOLOGY 2010; 11:705-19. [PMID: 20696007 PMCID: PMC6640454 DOI: 10.1111/j.1364-3703.2010.00625.x] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Phenolics are aromatic benzene ring compounds with one or more hydroxyl groups produced by plants mainly for protection against stress. The functions of phenolic compounds in plant physiology and interactions with biotic and abiotic environments are difficult to overestimate. Phenolics play important roles in plant development, particularly in lignin and pigment biosynthesis. They also provide structural integrity and scaffolding support to plants. Importantly, phenolic phytoalexins, secreted by wounded or otherwise perturbed plants, repel or kill many microorganisms, and some pathogens can counteract or nullify these defences or even subvert them to their own advantage. In this review, we discuss the roles of phenolics in the interactions of plants with Agrobacterium and Rhizobium.
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Affiliation(s)
- Amita Bhattacharya
- Institute of Himalayan Bioresource Technology (Council of Scientific and Industrial Research), Palampur, Himachal Pradesh, India
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331
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Hamel LP, Beaudoin N. Chitooligosaccharide sensing and downstream signaling: contrasted outcomes in pathogenic and beneficial plant-microbe interactions. PLANTA 2010; 232:787-806. [PMID: 20635098 DOI: 10.1007/s00425-010-1215-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 06/14/2010] [Indexed: 05/29/2023]
Abstract
In plants, short chitin oligosaccharides and chitosan fragments (collectively referred to as chitooligosaccharides) are well-known elicitors that trigger defense gene expression, synthesis of antimicrobial compounds, and cell wall strengthening. Recent findings have shed new light on chitin-sensing mechanisms and downstream activation of intracellular signaling networks that mediate plant defense responses. Interestingly, chitin receptors possess several lysin motif domains that are also found in several legume Nod factor receptors. Nod factors are chitin-related molecules produced by nitrogen-fixing rhizobia to induce root nodulation. The fact that chitin and Nod factor receptors share structural similarity suggests an evolutionary conserved relationship between mechanisms enabling recognition of both deleterious and beneficial microorganisms. Here, we will present an update on molecular events involved in chitooligosaccharide sensing and downstream signaling pathways in plants and will discuss how structurally related signals may lead to such contrasted outcomes during plant-microbe interactions.
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Affiliation(s)
- Louis-Philippe Hamel
- Faculté des Sciences, Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
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332
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García-Fraile P, Mulas-García D, Peix A, Rivas R, González-Andrés F, Velázquez E. Phaseolus vulgaris is nodulated in northern Spain by Rhizobium leguminosarum strains harboring two nodC alleles present in American Rhizobium etli strains: biogeographical and evolutionary implications. Can J Microbiol 2010; 56:657-66. [DOI: 10.1139/w10-048] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study a collection of rhizobial strains were isolated from effective nodules of Phaseolus vulgaris in a wide region of northern Spain, which is the major producer region of this legume in Spain. The analysis of their core genes, rrs, atpD, and recA, and the 16S–23S intergenic spacer showed that all isolates belong to the phylogenetic group of Rhizobium leguminosarum and some of them were identical to those of strains nodulating Vicia or Trifolium . None of the isolates was identified as Rhizobium etli ; however, all of them carry the nodC alleles α and γ harboured by American strains of this species. These alleles were also found in strains nodulating P. vulgaris in southern Spain identified as R. etli. These results suggest that R. etli was carried from America to Spain with common bean seeds, but that they could have found difficulties persisting in the soils of northern Spain, probably because of the climatic conditions. The symbiotic genes of this species could have been transferred, after the arrival of P. vulgaris, to strains of R. leguminosarum already present in northern Spanish soils.
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Affiliation(s)
- Paula García-Fraile
- Departamento de Microbiología y Genética, Universidad de Salamanca, Laboratorio 209, Edificio Departamental de Biología, Campus Miguel de Unamuno, Salamanca 37007, Spain
- Departamento de Ingeniería y Ciencias Agrarias, Universidad de León, León 24071, Spain
- Instituto de Recursos Naturales y Agrobiología, IRNASA-CSIC, Salamanca 37008, Spain
| | - Daniel Mulas-García
- Departamento de Microbiología y Genética, Universidad de Salamanca, Laboratorio 209, Edificio Departamental de Biología, Campus Miguel de Unamuno, Salamanca 37007, Spain
- Departamento de Ingeniería y Ciencias Agrarias, Universidad de León, León 24071, Spain
- Instituto de Recursos Naturales y Agrobiología, IRNASA-CSIC, Salamanca 37008, Spain
| | - Alvaro Peix
- Departamento de Microbiología y Genética, Universidad de Salamanca, Laboratorio 209, Edificio Departamental de Biología, Campus Miguel de Unamuno, Salamanca 37007, Spain
- Departamento de Ingeniería y Ciencias Agrarias, Universidad de León, León 24071, Spain
- Instituto de Recursos Naturales y Agrobiología, IRNASA-CSIC, Salamanca 37008, Spain
| | - Raúl Rivas
- Departamento de Microbiología y Genética, Universidad de Salamanca, Laboratorio 209, Edificio Departamental de Biología, Campus Miguel de Unamuno, Salamanca 37007, Spain
- Departamento de Ingeniería y Ciencias Agrarias, Universidad de León, León 24071, Spain
- Instituto de Recursos Naturales y Agrobiología, IRNASA-CSIC, Salamanca 37008, Spain
| | - Fernando González-Andrés
- Departamento de Microbiología y Genética, Universidad de Salamanca, Laboratorio 209, Edificio Departamental de Biología, Campus Miguel de Unamuno, Salamanca 37007, Spain
- Departamento de Ingeniería y Ciencias Agrarias, Universidad de León, León 24071, Spain
- Instituto de Recursos Naturales y Agrobiología, IRNASA-CSIC, Salamanca 37008, Spain
| | - Encarna Velázquez
- Departamento de Microbiología y Genética, Universidad de Salamanca, Laboratorio 209, Edificio Departamental de Biología, Campus Miguel de Unamuno, Salamanca 37007, Spain
- Departamento de Ingeniería y Ciencias Agrarias, Universidad de León, León 24071, Spain
- Instituto de Recursos Naturales y Agrobiología, IRNASA-CSIC, Salamanca 37008, Spain
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333
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The twin arginine transport system appears to be essential for viability in Sinorhizobium meliloti. J Bacteriol 2010; 192:5173-80. [PMID: 20675496 DOI: 10.1128/jb.00206-10] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The twin arginine transport (Tat) system is responsible for transporting prefolded proteins to the periplasmic space. The Tat pathway has been implicated in many bacterial cellular functions, including motility, biofilm formation, and pathogenesis and symbiosis. Since the annotation of Sinorhizobium meliloti Rm1021 genome suggests that there may be up to 94 putative Tat substrates, we hypothesized that characterizing the twin arginine transport system in this organism might yield unique data that could help in the understanding of twin arginine transport. To initiate this work we attempted a targeted mutagenesis of the tat locus. Despite repeated attempts using a number of different types of media, the attempts at mutation construction were unsuccessful unless the experiment was carried out in a strain that was merodiploid for tatABC. In addition, it was shown that a plasmid carrying tatABC was stable in the absence of antibiotic selection in a tat deletion background. Finally, fluorescence microscopy and live/dead assays of these cultures show a high proportion of dead and irregularly shaped cells, suggesting that the loss of tatABC is inversely correlated with viability. Taken together, the results of this work provide evidence that the twin arginine transport system of S. meliloti appears to be essential for viability under all the conditions that we had tested.
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334
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Bonaldi K, Gourion B, Fardoux J, Hannibal L, Cartieaux F, Boursot M, Vallenet D, Chaintreuil C, Prin Y, Nouwen N, Giraud E. Large-scale transposon mutagenesis of photosynthetic Bradyrhizobium sp. strain ORS278 reveals new genetic loci putatively important for nod-independent symbiosis with Aeschynomene indica. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:760-70. [PMID: 20459315 DOI: 10.1094/mpmi-23-6-0760] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Photosynthetic Bradyrhizobium strains possess the unusual ability to form nitrogen-fixing nodules on a specific group of legumes in the absence of Nod factors. To obtain insight into the bacterial genes involved in this Nod-independent symbiosis, we screened 15,648 Tn5 mutants of Bradyrhizobium sp. strain ORS278 for clones affected in root symbiosis with Aeschynomene indica. From the 268 isolated mutants, 120 mutants were altered in nodule development (Ndv(-)) and 148 mutants were found to be deficient in nitrogen fixation (Fix(-)). More than 50% of the Ndv(-) mutants were found to be altered in purine biosynthesis, strengthening the previous hypothesis of a symbiotic role of a bacterial purine derivative during the Nod-independent symbiosis. The other Ndv(-) mutants were auxotrophic for pyrimidines and amino acids (leucine, glutamate, and lysine) or impaired in genes encoding proteins of unknown function. The Fix(-) mutants were found to be affected in a wide variety of cellular processes, including both novel (n = 56) and previously identified (n = 31) genes important in symbiosis. Among the novel genes identified, several were involved in the Calvin cycle, suggesting that CO(2) fixation could play an important role during this symbiosis.
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Affiliation(s)
- Katia Bonaldi
- Laboratoire des Symbioses Tropicales et Méditerranéennes, IRD, UMR-IRD/SupAgro/INRA/UM2/CIRAD, F-34398 Montpellier, France
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335
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Koch M, Delmotte N, Rehrauer H, Vorholt JA, Pessi G, Hennecke H. Rhizobial adaptation to hosts, a new facet in the legume root-nodule symbiosis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:784-90. [PMID: 20459317 DOI: 10.1094/mpmi-23-6-0784] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Rhizobia are able to infect legume roots, elicit root nodules, and live therein as endosymbiotic, nitrogen-fixing bacteroids. Host recognition and specificity are the results of early programming events in bacteria and plants, in which important signal molecules play key roles. Here, we introduce a new aspect of this symbiosis: the adaptive response to hosts. This refers to late events in bacteroids in which specific genes are transcribed and translated that help the endosymbionts to meet the disparate environmental requirements imposed by the hosts in which they live. The host-adaptation concept was elaborated with Bradyrhizobium japonicum and three different legumes (soybean, cowpea, and siratro). Transcriptomes and proteomes in root-nodule bacteroids were analyzed and compared, and genes and proteins were identified which are specifically induced in only one of the three hosts. We focused on those determinants that were congruent in the two data sets of host-specific transcripts and proteins: seven for soybean, five for siratro, and two for cowpea. One gene cluster for a predicted ABC-type transporter, differentially expressed in siratro, was deleted in B. japonicum. The respective mutant had a symbiotic defect on siratro rather than on soybean or cowpea. This result demonstrates the value of the applied approach and corroborates the host-specific adaptation concept.
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Affiliation(s)
- Marion Koch
- Institute of Microbiology, ETH, Zurich, Switzerland
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336
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Tian CF, Young JPW, Wang ET, Tamimi SM, Chen WX. Population mixing of Rhizobium leguminosarum bv. viciae nodulating Vicia faba: the role of recombination and lateral gene transfer. FEMS Microbiol Ecol 2010; 73:563-76. [PMID: 20533948 DOI: 10.1111/j.1574-6941.2010.00909.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The level and mechanisms of population mixing among faba bean (Vicia faba) rhizobia of different geographic origins (three ecoregions of China and several Western countries) were analysed by sequencing three chromosomal housekeeping loci (atpD, recA and glnII) and one nodulation gene (nodD). Eight distinct sublineages of Rhizobium leguminosarum bv. viciae (Rlv) were identified by concatenated sequences of chromosomal loci. structure analysis revealed admixture patterns of Rlv populations of different geographic origins. Recombination, particularly among these chromosomal loci, was revealed to be an important microevolutionary force in shaping the observed genetic diversity and the phylogeny of Rlv. The phylogeny of nodD is largely independent of that of the chromosomal loci, reflecting multiple gene transfers between sublineages and possibly selection imposed by different faba bean gene pools. The dominant nodulation genotype of faba bean rhizobia in the spring growing region of China is identical to the prevalent type of Europe, while the winter growing region of China has another related, but distinct, dominant nodulation genotype. Although several geographically specific sublineages of Rlv were observed, recombination and lateral gene transfer have driven the process of population mixing among different ecoregions of China or between China and countries to the west.
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Affiliation(s)
- Chang Fu Tian
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
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337
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Genetic and metabolic divergence within a Rhizobium leguminosarum bv. trifolii population recovered from clover nodules. Appl Environ Microbiol 2010; 76:4593-600. [PMID: 20472725 DOI: 10.1128/aem.00667-10] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhizobia are able to establish symbiosis with leguminous plants and usually occupy highly complex soil habitats. The large size and complexity of their genomes are considered advantageous, possibly enhancing their metabolic and adaptive potential and, in consequence, their competitiveness. A population of Rhizobium leguminosarum bv. trifolii organisms recovered from nodules of several clover plants growing in each other's vicinity in the soil was examined regarding possible relationships between their metabolic-physiological properties and their prevalence in such a local population. Genetic and metabolic variability within the R. leguminosarum bv. trifolii strains occupying nodules of several plants was of special interest, and both types were found to be considerable. Moreover, a prevalence of metabolically versatile strains, i.e., those not specializing in utilization of any group of substrates, was observed by combining statistical analyses of Biolog test results with the frequency of occurrence of genetically distinct strains. Metabolic versatility with regard to nutritional requirements was not directly advantageous for effectiveness in the symbiotic interaction with clover: rhizobia with specialized metabolism were more effective in symbiosis but rarely occurred in the population. The significance of genetic and, especially, metabolic complexity of bacteria constituting a nodule population is discussed in the context of strategies employed by bacteria in competition.
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338
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Vauclare P, Bligny R, Gout E, De Meuron V, Widmer F. Metabolic and structural rearrangement during dark-induced autophagy in soybean (Glycine max L.) nodules: an electron microscopy and 31P and 13C nuclear magnetic resonance study. PLANTA 2010; 231:1495-504. [PMID: 20358222 DOI: 10.1007/s00425-010-1148-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 02/26/2010] [Indexed: 05/13/2023]
Abstract
The effects of dark-induced stress on the evolution of the soluble metabolites present in senescent soybean (Glycine max L.) nodules were analysed in vitro using (13)C- and (31)P-NMR spectroscopy. Sucrose and trehalose were the predominant soluble storage carbons. During dark-induced stress, a decline in sugars and some key glycolytic metabolites was observed. Whereas 84% of the sucrose disappeared, only one-half of the trehalose was utilised. This decline coincides with the depletion of Gln, Asn, Ala and with an accumulation of ureides, which reflect a huge reduction of the N(2) fixation. Concomitantly, phosphodiesters and compounds like P-choline, a good marker of membrane phospholipids hydrolysis and cell autophagy, accumulated in the nodules. An autophagic process was confirmed by the decrease in cell fatty acid content. In addition, a slight increase in unsaturated fatty acids (oleic and linoleic acids) was observed, probably as a response to peroxidation reactions. Electron microscopy analysis revealed that, despite membranes dismantling, most of the bacteroids seem to be structurally intact. Taken together, our results show that the carbohydrate starvation induced in soybean by dark stress triggers a profound metabolic and structural rearrangement in the infected cells of soybean nodule which is representative of symbiotic cessation.
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Affiliation(s)
- Pierre Vauclare
- Laboratory of Plant Biology and Physiology, Biology Building UNIL, Room 5449, 1015 Lausanne, Switzerland.
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339
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Mierzwa B, Wdowiak-Wróbel S, Kalita M, Gnat S, Małek W. Insight into the evolutionary history of symbiotic genes of Robinia pseudoacacia rhizobia deriving from Poland and Japan. Arch Microbiol 2010; 192:341-50. [DOI: 10.1007/s00203-010-0561-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 01/25/2010] [Accepted: 03/02/2010] [Indexed: 11/29/2022]
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340
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Diouf D, Fall D, Chaintreuil C, Ba A, Dreyfus B, Neyra M, Ndoye I, Moulin L. Phylogenetic analyses of symbiotic genes and characterization of functional traits of
Mesorhizobium
spp. strains associated with the promiscuous species
Acacia seyal
Del. J Appl Microbiol 2010; 108:818-830. [DOI: 10.1111/j.1365-2672.2009.04500.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- D. Diouf
- Département de Biologie Végétale, Université Cheikh Anta Diop, BP, Dakar, Senegal
- Laboratoire Commun de Microbiologie IRD/ISRA/UCAD, BP, Dakar, Senegal
| | - D. Fall
- Département de Biologie Végétale, Université Cheikh Anta Diop, BP, Dakar, Senegal
- Laboratoire Commun de Microbiologie IRD/ISRA/UCAD, BP, Dakar, Senegal
| | - C. Chaintreuil
- IRD, UMR 113 Symbioses Tropicales et Méditerranéennes F‐34398, Montpellier, France
| | - A.T. Ba
- Département de Biologie Végétale, Université Cheikh Anta Diop, BP, Dakar, Senegal
- Université de Ziguinchor, Ziguinchor, Senegal
| | - B. Dreyfus
- IRD, UMR 113 Symbioses Tropicales et Méditerranéennes F‐34398, Montpellier, France
| | - M. Neyra
- IRD, UMR 113 Symbioses Tropicales et Méditerranéennes F‐34398, Montpellier, France
| | - I. Ndoye
- Département de Biologie Végétale, Université Cheikh Anta Diop, BP, Dakar, Senegal
- Laboratoire Commun de Microbiologie IRD/ISRA/UCAD, BP, Dakar, Senegal
| | - L. Moulin
- IRD, UMR 113 Symbioses Tropicales et Méditerranéennes F‐34398, Montpellier, France
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341
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Carvalho FM, Souza RC, Barcellos FG, Hungria M, Vasconcelos ATR. Genomic and evolutionary comparisons of diazotrophic and pathogenic bacteria of the order Rhizobiales. BMC Microbiol 2010; 10:37. [PMID: 20144182 PMCID: PMC2907836 DOI: 10.1186/1471-2180-10-37] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 02/08/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Species belonging to the Rhizobiales are intriguing and extensively researched for including both bacteria with the ability to fix nitrogen when in symbiosis with leguminous plants and pathogenic bacteria to animals and plants. Similarities between the strategies adopted by pathogenic and symbiotic Rhizobiales have been described, as well as high variability related to events of horizontal gene transfer. Although it is well known that chromosomal rearrangements, mutations and horizontal gene transfer influence the dynamics of bacterial genomes, in Rhizobiales, the scenario that determine pathogenic or symbiotic lifestyle are not clear and there are very few studies of comparative genomic between these classes of prokaryotic microorganisms trying to delineate the evolutionary characterization of symbiosis and pathogenesis. RESULTS Non-symbiotic nitrogen-fixing bacteria and bacteria involved in bioremediation closer to symbionts and pathogens in study may assist in the origin and ancestry genes and the gene flow occurring in Rhizobiales. The genomic comparisons of 19 species of Rhizobiales, including nitrogen-fixing, bioremediators and pathogens resulted in 33 common clusters to biological nitrogen fixation and pathogenesis, 15 clusters exclusive to all nitrogen-fixing bacteria and bacteria involved in bioremediation, 13 clusters found in only some nitrogen-fixing and bioremediation bacteria, 01 cluster exclusive to some symbionts, and 01 cluster found only in some pathogens analyzed. In BBH performed to all strains studied, 77 common genes were obtained, 17 of which were related to biological nitrogen fixation and pathogenesis. Phylogenetic reconstructions for Fix, Nif, Nod, Vir, and Trb showed possible horizontal gene transfer events, grouping species of different phenotypes. CONCLUSIONS The presence of symbiotic and virulence genes in both pathogens and symbionts does not seem to be the only determinant factor for lifestyle evolution in these microorganisms, although they may act in common stages of host infection. The phylogenetic analysis for many distinct operons involved in these processes emphasizes the relevance of horizontal gene transfer events in the symbiotic and pathogenic similarity.
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Affiliation(s)
- Fabíola M Carvalho
- Laboratório Nacional de Computação Científica, Laboratório de Bioinformática, Av Getúlio Vargas 333, 25651-075 Petrópolis, Rio de Janeiro, Brazil
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342
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Velázquez E, Valverde A, Rivas R, Gomis V, Peix Á, Gantois I, Igual JM, León-Barrios M, Willems A, Mateos PF, Martínez-Molina E. Strains nodulating Lupinus albus on different continents belong to several new chromosomal and symbiotic lineages within Bradyrhizobium. Antonie van Leeuwenhoek 2010; 97:363-76. [DOI: 10.1007/s10482-010-9415-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Accepted: 01/12/2010] [Indexed: 11/25/2022]
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343
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Wang C, Kemp J, Da Fonseca IO, Equi RC, Sheng X, Charles TC, Sobral BWS. Sinorhizobium meliloti 1021 loss-of-function deletion mutation in chvI and its phenotypic characteristics. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:153-160. [PMID: 20064059 DOI: 10.1094/mpmi-23-2-0153] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Bacterial two-component regulatory systems (TCS) are common components of complex regulatory networks and cascades. In Sinorhizobium meliloti, the TCS ExoS/ChvI controls exopolysaccharide succinoglycan production and flagellum biosynthesis. Although this system plays a crucial role in establishing the symbiosis between S. meliloti and its host plant, it is not well characterized. Attempts to generate complete loss-of-function mutations in either exoS or chvI in S. meliloti have been unsuccessful; thus, it was previously suggested that exoS or chvI are essential genes for bacterial cell growth. We constructed a chvI mutant by completely deleting the open reading frame encoding this gene. The mutant strain failed to grow on complex medium, exhibited lower tolerance to acidic condition, produced significantly less poly-3-hydroxybutyrate than the wild type, was hypermotile, and exhibited an altered lipopolysaccharide profile. In addition, this mutant was defective in symbiosis with Medicago truncatula and M. sativa (alfalfa), although it induced root hair deformation as efficiently as the wild type. Together, our results demonstrate that ChvI is intimately involved in regulatory networks involving the cell envelope and metabolism; however, its precise role within the regulatory network remains to be determined.
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Affiliation(s)
- Chunxia Wang
- Virginia Bioinformatics Instutue, Virginia Polytechnic Institute and STate University, Blacksburg 24061, USA.
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344
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Medeot DB, Sohlenkamp C, Dardanelli MS, Geiger O, García de Lema M, López-Lara IM. Phosphatidylcholine levels of peanut-nodulatingBradyrhizobiumsp. SEMIA 6144 affect cell size and motility. FEMS Microbiol Lett 2010; 303:123-31. [DOI: 10.1111/j.1574-6968.2009.01873.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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345
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The enoyl-ACP reductase gene, fabI1, of Sinorhizobium meliloti is involved in salt tolerance, swarming mobility and nodulation efficiency. CHINESE SCIENCE BULLETIN 2010. [DOI: 10.1007/s11434-009-0721-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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346
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Dardanelli MS, Carletti SM, Paulucci NS, Medeot DB, Cáceres EAR, Vita FA, Bueno M, Fumero MV, Garcia MB. Benefits of Plant Growth-Promoting Rhizobacteria and Rhizobia in Agriculture. PLANT GROWTH AND HEALTH PROMOTING BACTERIA 2010. [DOI: 10.1007/978-3-642-13612-2_1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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347
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Downie JA. The roles of extracellular proteins, polysaccharides and signals in the interactions of rhizobia with legume roots. FEMS Microbiol Rev 2009; 34:150-70. [PMID: 20070373 DOI: 10.1111/j.1574-6976.2009.00205.x] [Citation(s) in RCA: 227] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Rhizobia adopt many different lifestyles including survival in soil, growth in the rhizosphere, attachment to root hairs and infection and growth within legume roots, both in infection threads and in nodules where they fix nitrogen. They are actively involved in extracellular signalling to their host legumes to initiate infection and nodule morphogenesis. Rhizobia also use quorum-sensing gene regulation via N-acyl-homoserine lactone signals and this can enhance their interaction with legumes as well as their survival under stress and their ability to induce conjugation of plasmids and symbiotic islands, thereby spreading their symbiotic capacity. They produce several surface polysaccharides that are critical for attachment and biofilm formation; some of these polysaccharides are specific for their growth on root hairs and can considerably enhance their ability to infect their host legumes. Different rhizobia use several different types of protein secretion mechanisms (Types I, III, IV, V and VI), and many of the secreted proteins play an important role in their interaction with plants. This review summarizes many of the aspects of the extracellular biology of rhizobia, in particular in relation to their symbiotic interaction with legumes.
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348
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Paschke M, Horiuchi J, Vivanco J, Perry L, Alford É. Chemical Signals in the Rhizosphere. ACTA ACUST UNITED AC 2009. [DOI: 10.1201/9781420005585.ch11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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349
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Müller MG, Forsberg LS, Keating DH. The rkp-1 cluster is required for secretion of Kdo homopolymeric capsular polysaccharide in Sinorhizobium meliloti strain Rm1021. J Bacteriol 2009; 191:6988-7000. [PMID: 19734304 PMCID: PMC2772494 DOI: 10.1128/jb.00466-09] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Accepted: 08/31/2009] [Indexed: 11/20/2022] Open
Abstract
Under conditions of nitrogen stress, leguminous plants form symbioses with soil bacteria called rhizobia. This partnership results in the development of structures called root nodules, in which differentiated endosymbiotic bacteria reduce molecular dinitrogen for the host. The establishment of rhizobium-legume symbioses requires the bacterial synthesis of oligosaccharides, exopolysaccharides, and capsular polysaccharides. Previous studies suggested that the 3-deoxy-D-manno-oct-2-ulopyranosonic acid (Kdo) homopolymeric capsular polysaccharide produced by strain Sinorhizobium meliloti Rm1021 contributes to symbiosis with Medicago sativa under some conditions. However, a conclusive symbiotic role for this polysaccharide could not be determined due to a lack of mutants affecting its synthesis. In this study, we have further characterized the synthesis, secretion, and symbiotic function of the Kdo homopolymeric capsule. We showed that mutants lacking the enigmatic rkp-1 gene cluster fail to display the Kdo capsule on the cell surface but accumulate an intracellular polysaccharide of unusually high M(r). In addition, we have demonstrated that mutations in kdsB2, smb20804, and smb20805 affect the polymerization of the Kdo homopolymeric capsule. Our studies also suggest a role for the capsular polysaccharide in symbiosis. Previous reports have shown that the overexpression of rkpZ from strain Rm41 allows for the symbiosis of exoY mutants of Rm1021 that are unable to produce the exopolysaccharide succinoglycan. Our results demonstrate that mutations in the rkp-1 cluster prevent this phenotypic suppression of exoY mutants, although mutations in kdsB2, smb20804, and smb20805 have no effect.
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Affiliation(s)
- Maike G. Müller
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois 60153, Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - Lennart S. Forsberg
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois 60153, Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - David H. Keating
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois 60153, Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
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350
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Alexandre A, Brígido C, Laranjo M, Rodrigues S, Oliveira S. Survey of Chickpea Rhizobia diversity in Portugal reveals the predominance of species distinct from Mesorhizobium ciceri and Mesorhizobium mediterraneum. MICROBIAL ECOLOGY 2009; 58:930-941. [PMID: 19468700 DOI: 10.1007/s00248-009-9536-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Accepted: 05/06/2009] [Indexed: 05/27/2023]
Abstract
Several Mesorhizobium species are able to induce effective nodules in chickpea, one of the most important legumes worldwide. Our aims were to examine the biogeography of chickpea rhizobia, to search for a predominant species, and to identify the most efficient microsymbiont, considering Portugal as a case study. One hundred and ten isolates were obtained from continental Portugal and Madeira Island. The 16S ribosomal RNA gene phylogeny revealed that isolates are highly diverse, grouping with most Mesorhizobium type strains, in four main clusters (A-D). Interestingly, only 33% of the isolates grouped with Mesorhizobium ciceri (cluster B) or Mesorhizobium mediterraneum (cluster D), the formerly described specific chickpea microsymbionts. Most isolates belong to cluster A, showing higher sequence similarity with Mesorhizobium huakuii and Mesorhizobium amorphae. The association found between the province of origin and species cluster of the isolates suggests biogeography patterns: most isolates from the north, center, and south belong to clusters B, A, and D, respectively. Most of the highly efficient isolates (symbiotic effectiveness >75%) belong to cluster B. A correlation was found between species cluster and origin soil pH of the isolates, suggesting that pH is a key environmental factor, which influences the species geographic distribution. To our knowledge, this is one of the few surveys on chickpea rhizobia and the first systematic assessment of indigenous rhizobia in Portugal.
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Affiliation(s)
- Ana Alexandre
- Laboratório de Microbiologia do Solo, Instituto de Ciências Agrárias Mediterrânicas (I.C.A.M.), Universidade de Evora, Evora, Portugal
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