Isolation and Characterization of a pSym Locus ofRhizobiumsp. BR816That Extends Nodulation Ability of Narrow Host RangePhaseolus vulgarisSymbionts toLeucaena leucocephala

Rhijn, Pieternel van

doi:10.1094/mpmi-9-0074

Cited by 28 publications

(15 citation statements)

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“…A mutation specifically blocking the production of this glucomannan considerably reduced both root‐hair attachment by R. leguminosarum and the ability of the mutant strain to compete with the wild type during nodule infection (Williams et al , 2008). It is likely that the accumulation of R. leguminosarum on the root hairs enhances delivery of Nod factors to the root hairs and as proposed previously (van Rhijn et al , 1996), the accumulation of rhizobia on root hairs might reduce (but not abolish) the level of Nod‐factor specificity as a consequence of increased levels of Nod factors delivered to root hairs. This could explain the observation (Diaz et al , 1989) that transgenic clover roots expressing a pea lectin could be nodulated by R. leguminosarum bv.…”

Section: Rhizobial Extracellular Components Associated With Root Attasupporting

confidence: 55%

“…Proteins secreted via this pathway are translocated across the inner and outer membranes without a periplasmic intermediate stage (Koronakis et al , 2004). NodO, which is present in some rhizobia and can extend the ability to nodulate different legumes, is one such protein (Economou et al , 1994; van Rhijn et al , 1996; Vlassak et al , 1998). NodO is a calcium‐binding protein that forms cation‐selective channels in membranes (Economou et al , 1990; Sutton et al , 1994), and it has been proposed that NodO may complement Nod factor function by promoting the movement of cations across the root‐hair membrane (Miwa et al , 2006) because in the absence of host‐specific Nod factors nodO is required to initiate infection in root hairs (Walker & Downie, 2000).…”

Section: Extracellular Signalling In Symbiotic Interactionsmentioning

confidence: 99%

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The roles of extracellular proteins, polysaccharides and signals in the interactions of rhizobia with legume roots

2010

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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. ForewordThis article will focus mostly on the aspects of extracellular biology associated with Rhizobium-legume interactions, ranging from initial attraction and attachment through to root colonization and infection. It will start with a summary overview of the essential events leading to nodule formation on legumes by almost all rhizobia. These events include exchange of signals between the two prospective symbiotic partners and the ability of the bacteria to initiate developmental changes in legumes leading to the formation of infected nitrogen-fixing nodules. The review will then focus on how the extracellular biology of rhizobia modifies and enhances these different stages of interactions with legumes, particularly those that are infected via root-hair infections. To optimize legume infection and form effective nitrogenfixing nodules, rhizobia export different surface polysaccharides and proteins, deliver proteins into plant cells and use quorum-sensing regulation of gene expression to coordinate their behaviour in ways that enhance and spread their symbiotic capacity. Rhizobia are also highly attuned to recognize and utilize various plant-made components, some of which act as signals and others as nutrients during different stages of the interaction.

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Section: Rhizobial Extracellular Components Associated With Root Attasupporting

confidence: 55%

Section: Extracellular Signalling In Symbiotic Interactionsmentioning

confidence: 99%

The roles of extracellular proteins, polysaccharides and signals in the interactions of rhizobia with legume roots

2010

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“…trifolii nodE, Rhizobium sp. NGR234 nodS and nodU, and Rhizobium tropici nodU (van Rhijn et al, 1996;Vlassak et al, 1998). Moreover, NodO expression confers the ability to nodulate L. leucocephala to Azorhizobium caulinodans, Rhizobium etli, R. leguminosarum bv.…”

Section: Nodomentioning

confidence: 99%

“…viciae and Rhizobium sp. BR816 (de Maagd et al, 1989a;van Rhijn et al, 1996), and as the prsDE genes are more widely conserved among rhizobia (York & Walker, 1997), it seems likely that NodO exploits secretion through PrsDE rather than being its original cognate substrate. Finnie et al (1997) noted that a R. leguminosarum bv.…”

Section: Nodomentioning

confidence: 99%

Rhizobial secreted proteins as determinants of host specificity in the rhizobiumâlegume symbiosis

Fauvart

Michiels

2008

FEMS Microbiology Letters

136

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Rhizobia are Gram-negative bacteria than can elicit the formation of specialized organs, called root nodules, on leguminous host plants. Upon infection of the nodules, they differentiate into nitrogen-fixing bacteroids. An elaborate signal exchange precedes the symbiotic interaction. In general, both rhizobia and host plants exhibit narrow specificity. Rhizobial factors contributing to this specificity include Nod factors and surface polysaccharides. It is becoming increasingly clear that protein secretion is important in determining the outcome of the interaction as well. This paper discusses our current understanding of the symbiotic role played by rhizobial secreted proteins, transported both by secretion systems that are of general use, such as the type I secretion system, and by specialized, host-targeting secretion systems, such as the type III, type IV and type VI secretion systems.

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“…mimosae pSym. It has been shown that heterologous expression of nodO can improve nodulation of L. leucocephala by different rhizobia and can even extend the host range [54, 55]. …”

Section: Resultsmentioning

confidence: 99%

Genomic basis of symbiovar mimosae in Rhizobium etli

Rogel¹,

Bustos²,

Santamaría³

et al. 2014

BMC Genomics

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BackgroundSymbiosis genes (nod and nif) involved in nodulation and nitrogen fixation in legumes are plasmid-borne in Rhizobium. Rhizobial symbiotic variants (symbiovars) with distinct host specificity would depend on the type of symbiosis plasmid. In Rhizobium etli or in Rhizobium phaseoli, symbiovar phaseoli strains have the capacity to form nodules in Phaseolus vulgaris while symbiovar mimosae confers a broad host range including different mimosa trees.ResultsWe report on the genome of R. etli symbiovar mimosae strain Mim1 and its comparison to that from R. etli symbiovar phaseoli strain CFN42. Differences were found in plasmids especially in the symbiosis plasmid, not only in nod gene sequences but in nod gene content. Differences in Nod factors deduced from the presence of nod genes, in secretion systems or ACC-deaminase could help explain the distinct host specificity. Genes involved in P. vulgaris exudate uptake were not found in symbiovar mimosae but hup genes (involved in hydrogen uptake) were found. Plasmid pRetCFN42a was partially contained in Mim1 and a plasmid (pRetMim1c) was found only in Mim1. Chromids were well conserved.ConclusionsThe genomic differences between the two symbiovars, mimosae and phaseoli may explain different host specificity. With the genomic analysis presented, the term symbiovar is validated. Furthermore, our data support that the generalist symbiovar mimosae may be older than the specialist symbiovar phaseoli.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-575) contains supplementary material, which is available to authorized users.

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Isolation and Characterization of a pSym Locus ofRhizobiumsp. BR816That Extends Nodulation Ability of Narrow Host RangePhaseolus vulgarisSymbionts toLeucaena leucocephala

Cited by 28 publications

References 0 publications

The roles of extracellular proteins, polysaccharides and signals in the interactions of rhizobia with legume roots

The roles of extracellular proteins, polysaccharides and signals in the interactions of rhizobia with legume roots

Rhizobial secreted proteins as determinants of host specificity in the rhizobiumâlegume symbiosis

Genomic basis of symbiovar mimosae in Rhizobium etli

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Isolation and Characterization of a pSym Locus ofRhizobiumsp. BR816That Extends Nodulation Ability of Narrow Host RangePhaseolus vulgarisSymbionts toLeucaena leucocephala

Cited by 28 publications

References 0 publications

The roles of extracellular proteins, polysaccharides and signals in the interactions of rhizobia with legume roots

The roles of extracellular proteins, polysaccharides and signals in the interactions of rhizobia with legume roots

Rhizobial secreted proteins as determinants of host specificity in the rhizobiumâlegume symbiosis

Genomic basis of symbiovar mimosae in Rhizobium etli

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Rhizobial secreted proteins as determinants of host specificity in the rhizobiumâlegume symbiosis