High‐resolution transcriptional analysis of the symbiotic plasmid of <i>Rhizobium</i> sp. NGR234

Perret, Xavier; Freiberg, Christoph; Rosenthal, André; Broughton, W. J.; Fellay, R.

doi:10.1046/j.1365-2958.1999.01361.x

Cited by 137 publications

(97 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Sequence analysis showed that pNGR234a carries 19 sequences homologous to conserved NodD-dependent promoter elements (nod boxes), 5 of which control the expression of known nod operons (87,195). No significant difference was found between the consensus sequence derived for nod boxes of pNGR234a and those published for other rhizobia (269d, 278).…”

Section: Nod Boxes: Variations On a Themementioning

confidence: 98%

Molecular Basis of Symbiotic Promiscuity

Perret

Staehelin

Broughton

2000

Microbiol Mol Biol Rev

Self Cite

881

630

View full text Add to dashboard Cite

SUMMARY Eukaryotes often form symbioses with microorganisms. Among these, associations between plants and nitrogen-fixing bacteria are responsible for the nitrogen input into various ecological niches. Plants of many different families have evolved the capacity to develop root or stem nodules with diverse genera of soil bacteria. Of these, symbioses between legumes and rhizobia (Azorhizobium, Bradyrhizobium, Mesorhizobium, and Rhizobium) are the most important from an agricultural perspective. Nitrogen-fixing nodules arise when symbiotic rhizobia penetrate their hosts in a strictly controlled and coordinated manner. Molecular codes are exchanged between the symbionts in the rhizosphere to select compatible rhizobia from pathogens. Entry into the plant is restricted to bacteria that have the “keys” to a succession of legume “doors”. Some symbionts intimately associate with many different partners (and are thus promiscuous), while others are more selective and have a narrow host range. For historical reasons, narrow host range has been more intensively investigated than promiscuity. In our view, this has given a false impression of specificity in legume-Rhizobium associations. Rather, we suggest that restricted host ranges are limited to specific niches and represent specialization of widespread and more ancestral promiscuous symbioses. Here we analyze the molecular mechanisms governing symbiotic promiscuity in rhizobia and show that it is controlled by a number of molecular keys.

show abstract

Section: Nod Boxes: Variations On a Themementioning

confidence: 98%

Molecular Basis of Symbiotic Promiscuity

Perret

Staehelin

Broughton

2000

Microbiol Mol Biol Rev

Self Cite

881

630

View full text Add to dashboard Cite

show abstract

“…rengei strain B3 and Astragalus sinicus. The gene was expressed to produce PCs and accumulate Cd 2+ , under the control of bacteroid-specific promoter, the nifH gene (Perret et al, 1999).…”

Section: Genetically-engineered Approachmentioning

confidence: 99%

New advances in plant growth-promoting rhizobacteria for bioremediation

Zhuang

Chen

Shim

et al. 2007

Environment International

521

197

View full text Add to dashboard Cite

“…The soil adjacent to plant roots is generally acidic, with pH values between 5 and 6.5 (Marschner, 1995). As expression of T3SS genes occurs in the early stages of the infection process (Perret et al, 1999), the environmental pH could be a factor affecting the activity of these genes. To elucidate how the pH could affect the expression of ttsI and nodA, b-galactosidase assays were carried out, adjusting the pH of the YM medium to the range 6-8.…”

Section: Regulation Of Ttsi By Flavonoids and Phmentioning

confidence: 99%

Regulation and symbiotic significance of nodulation outer proteins secretion in Sinorhizobium fredii HH103

et al. 2008

View full text Add to dashboard Cite

In this work we show that the Sinorhizobium fredii HH103 ttsI gene is essential for the expression of the tts genes and secretion of nodulation outer proteins (Nops). Moreover, we demonstrate for the first time, to our knowledge, that the nod box preceding ttsI is necessary for Nops secretion. TtsI is responsible for the transcriptional activation of nopX, nopA, rhcJ and rhcQ. We confirm that the S. fredii HH103 ttsI gene is activated by NodD1 and repressed by NolR. In contrast, NodD2 is not involved in the regulation of ttsI expression. Despite the dependence of expression of both ttsI and nodA on NodD1 and flavonoids, clear differences in the capacity of some flavonoids to activate these genes were found. The expression of the ttsI and nodA genes was also sensitive to differences in the pH of the media. Secretion of Nops in the ttsI mutant could not be complemented with a DNA fragment containing the ttsI gene and its nod box, but it was restored when a plasmid harbouring the ttsI, rhcC2 and y4xK genes was transferred to the mutant strain. The symbiotic effect of Nops secretion was host-dependent but independent of the type of nodule formed by the host legume. Nops are beneficial in the symbiosis with Glycine max and Glycyrrhiza uralensis, and detrimental in the case of the tropical legume Erythrina variegata.

show abstract

High‐resolution transcriptional analysis of the symbiotic plasmid of Rhizobium sp. NGR234

Abstract: Summary Most of the bacterial genes involved in nodulation of

Cited by 137 publications

References 37 publications

Molecular Basis of Symbiotic Promiscuity

Molecular Basis of Symbiotic Promiscuity

New advances in plant growth-promoting rhizobacteria for bioremediation

Regulation and symbiotic significance of nodulation outer proteins secretion in Sinorhizobium fredii HH103

Contact Info

Product

Resources

About