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PMID: 8710923 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. Research Support, U.S. Gov't, P.H.S.

Low molecular weight EPS II of Rhizobium meliloti allows nodule invasion in Medicago sativa.

Proceedings of the National Academy of Sciences of the United States of America ·Vol. 93 ·No. 16 ·1996-08-06 ·Pages 8636-41

González JE, Reuhs BL, Walker GC

Abstract

Effective invasion of alfalfa by Rhizobium meliloti Rm1021 normally requires the presence of succinoglycan, an exopolysaccharide (EPS) produced by the bacterium. However, Rm1021 has the ability to produce a second EPS (EPS II) that can suppress the symbiotic defects of succinoglycan-deficient strains. EPS II is a polymer of modified glucose-(beta-1,3)-galactose subunits and is produced by Rm1021 derivatives carrying either an expR101 or mucR mutation. If the ability to synthesize succinoglycan is blocked genetically, expR101 derivatives of Rm1021 are nodulation-proficient, whereas mucR derivatives of Rm1021 are not. The difference in nodulation proficiency between these two classes of EPS II-producing strains is due to the specific production of a low molecular weight form of EPS II by expR101 strains. A low molecular weight EPS II fraction consisting of 15-20 EPS II disaccharide subunits efficiently allows nodule invasion by noninfective strains when present in amounts as low as 7 pmol per plant, suggesting that low molecular weight EPS II may act as a symbiotic signal during infection.

MeSH Terms
Genetic Complementation Test Medicago sativa/microbiology Molecular Weight Nitrogen Fixation Polysaccharides, Bacterial/chemistry,metabolism Rhizobium/pathogenicity Symbiosis
Chemicals
Polysaccharides, Bacterial succinoglycan
Authors & Affiliations
3 authors, click to expand affiliations / ORCID
González J E
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Reuhs B L
Walker G C
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38 references, click to expand
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Article Info
Journal
Proceedings of the National Academy of Sciences of the United States of America
Abbr.
Proc Natl Acad Sci U S A
ISSN
0027-8424
DOI
10.1073/pnas.93.16.8636
Published
1996-08-06
Pages
8636-41
Language
English
Region
United States
NLM ID
7505876
PMCID
PMC38725
Subset
IM
Grants
NIGMS NIH HHS · GM31030-14 · United States
External Links
PubMed source DOI: 10.1073/pnas.93.16.8636 PMC Full Text View journal details
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