Early production of rhizopine in nodules induced by Sinorhizobium meliloti strain L5-30.
Can J Microbiol
; 47(2): 165-71, 2001 Feb.
Article
en En
| MEDLINE
| ID: mdl-11261497
ABSTRACT
The rhizopine L-3-O-methyl-scyllo-inosamine (3-O-MSI) is metabolized by approximately 10% of the strains of Rhizobium leguminosarum by. viciae and Sinorhizobium meliloti. Rhizopine strains enjoy a substantial competitive advantage in nodulation, which is manifest before 14 days post-inoculation, implying that rhizopine is produced before this time. We were able to detect this compound in the roots of alfalfa (Medicago sativum L. cv. Hunter River) four days after germination (six days post-infection) with S. meliloti strain L5-30 by gas chromatography-mass spectrometry (GC-MS). At four days, nodules were not visible, and the concentration of rhizopine was extremely low, estimated at 67 pg/gfw (picograms/gram fresh weight). The amount increased gradually but remained low until 16 days, when there was a 50-fold increase from day four, by which time nodules were well established. This pattern of synthesis is consistent with previous studies indicating that rhizopine synthesis is regulated by nifA/ntrA regulatory genes, which are maximally expressed in bacteroids at the onset of nitrogen fixation. However, the low level of rhizopine synthesis must be responsible for the early effects on competition for nodulation. Production of rhizopine at this time most likely results from micro-aerobic induction of mos genes in free-living bacteria, either in the infection threads or in the rhizosphere.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Sinorhizobium meliloti
/
Medicago sativa
/
Inositol
Idioma:
En
Revista:
Can J Microbiol
Año:
2001
Tipo del documento:
Article
País de afiliación:
Australia