The NodA proteins of Rhizobium meliloti and Rhizobium tropici specify the N‐acylation of Nod factors by different fatty acids

Debelle, Frédéric; Plazanet, Claire; Roché, Philippe; Pujol, Céline; Savagnac, Arlette; Rosenberg, Charles; Promé, Jean‐Claude; Denarié, Jean

doi:10.1046/j.1365-2958.1996.00069.x

Cited by 63 publications

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“…We first tested the requirement for common nod genes, nodABC, which are necessary to elicit all known plant nodulation responses (Debellé et al, 1986;Swanson et al, 1987). The nodABC mutant SL44 and the nodA mutant GMI3253 should produce no NF and NFs that lack a lipid tail, respectively (Fisher et al, 1988;Debellé et al, 1996). Both strains failed to trigger calcium spiking in M. truncatula root hairs (Table II, Fig.…”

Section: S Meliloti Common Nodabc Genes Are Required To Trigger Calcmentioning

confidence: 99%

“…These genes, in turn, encode biosynthetic enzymes responsible for the assembly of a lipo-chitooligosaccharide signal, called Nod factor (NF), that triggers morphogenetic changes in the receptive host. NF is required for nodulation: Bacteria that fail to synthesize NF because of mutations in nod genes fail to elicit the morphological responses associated with nodulation.NFs isolated from loss-of-function bacterial nod mutants correspond to the predicted structure based on known nod gene function (Roche et al, 1991;Demont et al, 1993;Ardourel et al, 1994;Debellé et al, 1996). The nod genes are divided into two categories, common and host specific.…”

mentioning

confidence: 99%

“…NFs isolated from loss-of-function bacterial nod mutants correspond to the predicted structure based on known nod gene function (Roche et al, 1991;Demont et al, 1993;Ardourel et al, 1994;Debellé et al, 1996). The nod genes are divided into two categories, common and host specific.…”

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confidence: 99%

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Structure-Function Analysis of Nod Factor-Induced Root Hair Calcium Spiking in Rhizobium-Legume Symbiosis

Wais¹,

Keating

Long

2002

Plant Physiology

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In the Rhizobium-legume symbiosis, compatible bacteria and host plants interact through an exchange of signals: Host compounds promote the expression of bacterial biosynthetic nod (nodulation) genes leading to the production of a lipochito-oligosaccharide signal, the Nod factor (NF). The particular array of nod genes carried by a given species of Rhizobium determines the NF structure synthesized and defines the range of legume hosts by which the bacterium is recognized. Purified NF can induce early host responses even in the absence of live Rhizobium One of the earliest known host responses to NF is an oscillatory behavior of cytoplasmic calcium, or calcium spiking, in root hair cells, initially observed in Medicago spp. and subsequently characterized in four other genera (D.W. Ehrhardt, R. Wais, S.R. Long [1996] Cell 85: 673-681; S.A. Walker, V. Viprey, J.A. Downie [2000] Proc Natl Acad Sci USA 97: 13413-13418; D.W. Ehrhardt, J.A. Downie, J. Harris, R.J. Wais, and S.R. Long, unpublished data). We sought to determine whether live Rhizobium trigger a rapid calcium spiking response and whether this response is NF dependent. We show that, in the Sinorhizobium melilotiMedicago truncatula interaction, bacteria elicit a calcium spiking response that is indistinguishable from the response to purified NF. We determine that calcium spiking is a nod gene-dependent host response. Studies of calcium spiking in M. truncatula and alfalfa (Medicago sativa) also uncovered the possibility of differences in early NF signal transduction. We further demonstrate the sufficiency of the nod genes for inducing calcium spiking by using Escherichia coli BL21 (DE3) engineered to express 11 S. meliloti nod genes.The Rhizobium-legume interaction initiates the development of a novel organ on the root of the host plant, the nodule, and its colonization by the bacteria, resulting in a nitrogen-fixing symbiosis. Within the first 12 to 24 h, bacteria trigger a series of microscopically visible morphological changes. In the epidermis, altered growth of root hair cells (root hair deformation) is followed by root hair curling. Bacteria concurrently induce renewed cortical cell division that will lead to the formation of a root nodule. Invasion structures, called infection threads, initiate within curled root hairs and grow into the developing nodule. Bacteria are eventually released from infection threads into the cells of the nodule, where they begin fixing nitrogen. Thus, in a compatible interaction, Rhizobium elicits root hair deformation and curling, infection thread development, and cell division in the root cortex leading to nodule formation. These morphological responses are considered to be the hallmarks of nodulation.Nodulation occurs only when compatible species of legumes and Rhizobium come into contact. Thus, Sinorhizobium meliloti interacts with Medicago spp. but not Vicia spp., which in turn form nodules in the presence of Rhizobium leguminosarum bv viciae. The specificity of the interaction is based on a reciprocal exchange of sig...

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Section: S Meliloti Common Nodabc Genes Are Required To Trigger Calcmentioning

confidence: 99%

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confidence: 99%

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Structure-Function Analysis of Nod Factor-Induced Root Hair Calcium Spiking in Rhizobium-Legume Symbiosis

Wais¹,

Keating

Long

2002

Plant Physiology

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“…Even although the reducing terminus of LCOs produced by NGR⌬nodZ (pGMI449) and wild-type R. meliloti are identical, this strain is not able to nodulate M. sativa (data not shown). This indicates that although the sulphate group is necessary for nodulation of M. sativa, the nonreducing end of Nod factors also contributes to the determination of host range (Debellé et al, 1996). In other words, the presence of substituents on the non-reducing terminus can have both positive and negative effects on nodulation.…”

Section: Discussionmentioning

confidence: 99%

Sulphation of Rhizobium sp. NGR234 Nod factors is dependent on noeE, a new host‐specificity gene

Hanin

Jabbouri

Quesada-Vincens

et al. 1997

Molecular Microbiology

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SummaryRhizobia secrete specific lipo-chitooligosaccharide signals (LCOs) called Nod factors that are required for infection and nodulation of legumes. In Rhizobium sp. NGR234, the reducing N-acetyl-D-glucosamine of LCOs is substituted at C 6 with 2-O-methyl-L-fucose which can be acetylated or sulphated. We identified a flavonoid-inducible locus on the symbiotic plasmid pNGR234a that contains a new nodulation gene, noeE, which is required for the sulphation of NGR234 Nod factors (NodNGR). noeE was identified by conjugation into the closely related Rhizobium fredii strain USDA257, which produces fucosylated but non-sulphated Nod factors (NodUSDA). R. fredii transconjugants producing sulphated LCOs acquire the capacity to nodulate Calopogonium caeruleum. Furthermore, mutation of noeE (NGR⌬noeE ) abolishes the production of sulphated LCOs and prevents nodulation of Pachyrhizus tuberosus. The sulphotransferase activity linked to NoeE is specific for fucose. In contrast, the sulphotransferase NodH of Rhizobium meliloti seems to be less specific than NoeE, because its introduction into NGR⌬noeE leads to the production of a mixture of LCOs that are sulphated on C 6 of the reducing terminus and sulphated on the 2-O-methylfucose residue. Together, these findings show that noeE is a host-specificity gene which probably encodes a fucose-specific sulphotransferase.

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“…NodC produces chitooligosaccharides (Geremia et al 1994;Spaink et al 1994) and the oligosaccharide chain elongation by NodC occurs at the nonreducing end (Kamst et al 1997(Kamst et al , 1999Mergaert et al 1995). The deacetylase NodB removes the N-acetyl group for the nonreducing end (John et al 1993;, while nodA codes for an acyltransferase that links the acyl chain to the acetyl-free C-2 carbon of the nonreducing end of the oligosaccharide (Atkinson et al 1994;Rohrig et al 1994;Debelle et al 1996). Variation among LCO includes (1) length of the chitin backbone (3 to 6 Nacetylglucosamine units), (2) the nature of the lipid chain (saturated, unsaturated, α/β unsaturated or ω-1 hydroxylated fatty acids), (3) a number of specific components attached to the chitin backbone, including acetyl-, carbamoyl-, fucosyl-, glyceryl-, hydroxyl-, mannosyl-, and suphyl-groups (Hanin et al 1999).…”

Section: Microbe-to-plant Signals -Nod Factors Nod Factors and Their mentioning

confidence: 99%

Exploiting inter-organismal chemical communication for improved inoculants

Mabood¹,

Gray²,

Lee³

et al. 2006

Can. J. Plant Sci.

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[951][952][953][954][955][956][957][958][959][960][961][962][963][964][965][966]. The combination of rising fossil fuel prices and a need to reduce greenhouse gas emissions will lead to expanded use of crop inoculants (bio-fertilizers) both for increased production of biomass (for bio-fuels and soil C storage) and to reduce production of nitrous oxide, through increased reliance on biological nitrogen fixation. Over the last century inoculants have been improved through strain selection, improved carriers (including sterile carriers), and increased cell densities. During the last few decades our understanding of signalling between symbiotic bacteria and plants has expanded enormously, with the signalling between rhizobia and their legume hosts being the model system. Recent work has shown that adverse environmental conditions can inhibit this signalling and that addition of plant-to-microbe signals into inoculants can help overcome this. This is also true of addition of the microbe-to-plant signals that act as the return signals of this system; however, they have also been shown to cause a general and direct stimulation of plant growth that is not yet well understood. Finally, very recent work has shown that some of the plant growth-promoting rhizobacteria produce novel signal compounds that stimulate plant growth. This is a time of rapid increase in understanding with regard to plant-microbe signalling; the use of these signals in commercial inoculants offers a new wave in innovations for this industry at a time when there is great need.Key words: Inoculants, rhizobacteria, rhizobia, signalling Mabood, F., Gray, E. J., Lee, K. D., Supanjani, et Smith D. L. 2006. Exploitation de la médiation chimique entre les organismes pour créer de meilleurs inoculants. Can. J. Plant Sci. 86: 951-966. La hausse du prix des combustibles fossiles et la néces-sité de réduire les émissions de gaz à effet de serre déboucheront sur une utilisation accrue des inoculants en agriculture (engrais biologiques) pour la production d'une plus grande quantité de biomasse (pour les biocarburants et le stockage du carbone dans le sol) mais aussi pour la réduction des dégagements d'oxydes nitreux par un plus grand recours à des mécanismes biologiques pour fixer l'azote dans le sol. Au cours du siècle dernier, on a raffiné les inoculants par la sélection, amélioré les excipients (y compris les substrats stériles) et accru la population de cellules. Durant les quelque dernières décennies, nos connaissances sur les signaux que s'échangent microorganismes et végétaux en symbiose se sont considérablement élargies et le système de signalisation entre les rhizobiums et les légumineuses qui sont leur hôte est devenu un modèle du genre. Des recherches récentes indiquent que des conditions environnementales difficiles peuvent nuire à l'échange de signaux et qu'on peut surmonter ce problème en ajoutant des médiateurs plante-microorganisme à l'inoculant. La même remarque s'applique à l'addition de médiateurs microorganisme-plante qui véhiculent la répons...

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**The NodA proteins of Rhizobium meliloti and Rhizobium tropici specify the N‐acylation of Nod factors by different fatty acids**

Cited by 63 publications

References 0 publications

Structure-Function Analysis of Nod Factor-Induced Root Hair Calcium Spiking in Rhizobium-Legume Symbiosis

Structure-Function Analysis of Nod Factor-Induced Root Hair Calcium Spiking in Rhizobium-Legume Symbiosis

Sulphation of Rhizobium sp. NGR234 Nod factors is dependent on noeE, a new host‐specificity gene

Exploiting inter-organismal chemical communication for improved inoculants

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