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NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis

The establishment of nitrogen-fixing rhizobium-legume symbioses requires a highly complex cascade of events. In this molecular dialogue the bacterial NodD transcriptional regulators in conjunction with plant inducers, mostly flavonoids, are responsible for the biosynthesis and secretion of Nod facto...

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Autores principales: del Cerro, Pablo, Rolla-Santos, Amanda A. P., Valderrama-Fernández, Rocío, Gil-Serrano, Antonio, Bellogín, Ramón A., Gomes, Douglas Fabiano, Pérez-Montaño, Francisco, Megías, Manuel, Hungría, Mariangela, Ollero, Francisco Javier
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4838322/
https://www.ncbi.nlm.nih.gov/pubmed/27096734
http://dx.doi.org/10.1371/journal.pone.0154029
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author del Cerro, Pablo
Rolla-Santos, Amanda A. P.
Valderrama-Fernández, Rocío
Gil-Serrano, Antonio
Bellogín, Ramón A.
Gomes, Douglas Fabiano
Pérez-Montaño, Francisco
Megías, Manuel
Hungría, Mariangela
Ollero, Francisco Javier
author_facet del Cerro, Pablo
Rolla-Santos, Amanda A. P.
Valderrama-Fernández, Rocío
Gil-Serrano, Antonio
Bellogín, Ramón A.
Gomes, Douglas Fabiano
Pérez-Montaño, Francisco
Megías, Manuel
Hungría, Mariangela
Ollero, Francisco Javier
author_sort del Cerro, Pablo
collection PubMed
description The establishment of nitrogen-fixing rhizobium-legume symbioses requires a highly complex cascade of events. In this molecular dialogue the bacterial NodD transcriptional regulators in conjunction with plant inducers, mostly flavonoids, are responsible for the biosynthesis and secretion of Nod factors which are key molecules for successful nodulation. Other transcriptional regulators related to the symbiotic process have been identified in rhizobial genomes, including negative regulators such as NolR. Rhizobium tropici CIAT 899 is an important symbiont of common bean (Phaseolus vulgaris L.), and its genome encompasses intriguing features such as five copies of nodD genes, as well as other possible transcriptional regulators including the NolR protein. Here we describe and characterize a new regulatory gene located in the non-symbiotic plasmid pRtrCIAT899c, that shows homology (46% identity) with the nolR gene located in the chromosome of CIAT 899. The mutation of this gene, named nrcR (nolR-like plasmid c Regulator), enhanced motility and exopolysaccharide production in comparison to the wild-type strain. Interestingly, the number and decoration of Nod Factors produced by this mutant were higher than those detected in the wild-type strain, especially under salinity stress. The nrcR mutant showed delayed nodulation and reduced competitiveness with P. vulgaris, and reduction in nodule number and shoot dry weight in both P. vulgaris and Leucaena leucocephala. Moreover, the mutant exhibited reduced capacity to induce the nodC gene in comparison to the wild-type CIAT 899. The finding of a new nod-gene regulator located in a non-symbiotic plasmid may reveal the existence of even more complex mechanisms of regulation of nodulation genes in R. tropici CIAT 899 that may be applicable to other rhizobial species.
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spelling pubmed-48383222016-04-29 NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis del Cerro, Pablo Rolla-Santos, Amanda A. P. Valderrama-Fernández, Rocío Gil-Serrano, Antonio Bellogín, Ramón A. Gomes, Douglas Fabiano Pérez-Montaño, Francisco Megías, Manuel Hungría, Mariangela Ollero, Francisco Javier PLoS One Research Article The establishment of nitrogen-fixing rhizobium-legume symbioses requires a highly complex cascade of events. In this molecular dialogue the bacterial NodD transcriptional regulators in conjunction with plant inducers, mostly flavonoids, are responsible for the biosynthesis and secretion of Nod factors which are key molecules for successful nodulation. Other transcriptional regulators related to the symbiotic process have been identified in rhizobial genomes, including negative regulators such as NolR. Rhizobium tropici CIAT 899 is an important symbiont of common bean (Phaseolus vulgaris L.), and its genome encompasses intriguing features such as five copies of nodD genes, as well as other possible transcriptional regulators including the NolR protein. Here we describe and characterize a new regulatory gene located in the non-symbiotic plasmid pRtrCIAT899c, that shows homology (46% identity) with the nolR gene located in the chromosome of CIAT 899. The mutation of this gene, named nrcR (nolR-like plasmid c Regulator), enhanced motility and exopolysaccharide production in comparison to the wild-type strain. Interestingly, the number and decoration of Nod Factors produced by this mutant were higher than those detected in the wild-type strain, especially under salinity stress. The nrcR mutant showed delayed nodulation and reduced competitiveness with P. vulgaris, and reduction in nodule number and shoot dry weight in both P. vulgaris and Leucaena leucocephala. Moreover, the mutant exhibited reduced capacity to induce the nodC gene in comparison to the wild-type CIAT 899. The finding of a new nod-gene regulator located in a non-symbiotic plasmid may reveal the existence of even more complex mechanisms of regulation of nodulation genes in R. tropici CIAT 899 that may be applicable to other rhizobial species. Public Library of Science 2016-04-20 /pmc/articles/PMC4838322/ /pubmed/27096734 http://dx.doi.org/10.1371/journal.pone.0154029 Text en © 2016 del Cerro et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
del Cerro, Pablo
Rolla-Santos, Amanda A. P.
Valderrama-Fernández, Rocío
Gil-Serrano, Antonio
Bellogín, Ramón A.
Gomes, Douglas Fabiano
Pérez-Montaño, Francisco
Megías, Manuel
Hungría, Mariangela
Ollero, Francisco Javier
NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis
title NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis
title_full NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis
title_fullStr NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis
title_full_unstemmed NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis
title_short NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis
title_sort nrcr, a new transcriptional regulator of rhizobium tropici ciat 899 involved in the legume root-nodule symbiosis
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4838322/
https://www.ncbi.nlm.nih.gov/pubmed/27096734
http://dx.doi.org/10.1371/journal.pone.0154029
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