June
2004
, Volume
17
, Number
6
Pages
676
-
685
Authors
JoséMaría
Vinardell
,
1
Francisco Javier
Ollero
,
1
ángeles
Hidalgo
,
1
Francisco Javier
López-Baena
,
1
Carlos
Medina
,
1
Kalojan
Ivanov-Vangelov
,
1
Maribel
Parada
,
1
Nuria
Madinabeitia
,
1
María
del Rosario Espuny
,
1
Ramón Andrés
Bellogín
,
1
María
Camacho
,
2
Dulce-Nombre
Rodríguez-Navarro
,
2
María Eugenia
Soria-Díaz
,
3
Antonio M.
Gil-Serrano
,
3
José Enrique
Ruiz-Sainz
1
Affiliations
1Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, C.P. 41012, Sevilla, Spain; 2CIDA “Las Torres y Tomejil”, Apdo. Oficial, Alcalá del Río, Sevilla, Spain; 3Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, Apdo. 553, 41071-Sevilla, Spain
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RelatedArticle
Accepted 2 February 2004.
Abstract
We have investigated in Sinorhizobium fredii HH103-1 (=HH103 Strr) the influence of the nolR gene on the production of three different bacterial symbiotic signals: Nod factors, signal responsive (SR) proteins, and exopolysac-charide (EPS). The presence of multiple copies of nolR (in plasmid pMUS675) repressed the transcription of all the flavonoid-inducible genes analyzed: nodA, nodD1, nolO, nolX, noeL, rhcJ, hesB, and y4pF. Inactivation of nolR (mutant SVQ517) or its overexpression (presence of pMUS675) altered the amount of Nod factors detected. Mutant SVQ517 produced Nod factors carrying N-methyl residues at the nonreducing N-acetyl-glucosamine, which never have been detected in S. fredii HH103. Plasmid pMUS675 increased the amounts of EPS produced by HH103-1 and SVQ517. The flavonoid genistein repressed EPS production of HH103-1 and SVQ517 but the presence of pMUS675 reduced this repression. The presence of plasmid pMUS675 clearly decreased the secretion of SR proteins. Inactivation, or overexpression, of nolR decreased the capacity of HH103 to nodulate Glycine max. However, HH103-1 and SVQ517 carrying plasmid pMUS675 showed enhanced nodulation capacity with Vigna unguiculata. The nolR gene was positively identified in all S. fredii strains investigated, S. xinjiangense CCBAU110, and S. saheli USDA4102. Apparently, S. teranga USDA4101 does not contain this gene.
JnArticleKeywords
Additional keywords:
LCO,
symbiotic interaction.
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ArticleCopyright
© 2004 The American Phytopathological Society