Abstract
Five exopolysaccharide-deficient mutants were isolated after rhizobial strain 107 was subjected to transposon Tn5 mutagenesis. The amount of EPS produced by the mutants was dramatically decreased to between 3% and 6% of wild-type level. All mutants carried a singel copy of Tn5. Two mutants (NA3 and NA10) were complemented by the R. meliloti exoA gene and the functionally equivalent exoD gene of Rhizobium sp. strain NGR234. Two other mutants (NA7 and NA8) were complemented by the R. meliloti exoB gene and the functionally equivalent NGR234 exoC gene. The remaining mutant (NA11) was not complemented by any exo genes of R. meliloti or Rhizobium NGR234. All mutants induced normal nitrogen-fixing nodules on Astragalus sinicus, an indeterminate nodulating host.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bender G L and Rolfe B G 1985 A rapid assay for the Parasponia-Rhizobium symbiosis. Plant Sci. Lett. 38, 135–140.
Borthakur D, Barber C E, Lamb J W, Daniels M J, Downie J A and Johnston A W B 1986 A mutation that blocks exopolysaccharide synthesis prevents nodulation of peas by Rhizobium leguminosarum but not of beans by R. phaseoli. Mol. Gen. Genet. 203, 320–323.
Buendia A M, Enenkel B, Koplin R, Niehaus K, Arnold W and Puhler A 1991 The Rhizobium meliloti exoZ/exoB fragment of megaplasmid 2: ExoB functions as a UDP-glucose-4-epimerase and ExoZ shows homology to NodX of Rhizobium leguminosarum biovar viciae strain TOM. Mol. Microbiol. 5, 1519–1530.
Canter-Cremers H C J, Batley M, Redmond W, Eydems L, Breedveld M W, Zevenhuizen L P T M, Pees E, Wijffelman C J and Lugtenberg B J J 1990 Rhizobium leguminosarum exoB mutants are deficient in the synthesis of UDP-glucose-4-epimerase. J. Biol. Chem. 265, 21122–21127.
Chakravorty A K, Zurkowski W, Shine J and Rolfe B G 1982 Symbiotic nitrogen fixation: molecular cloning of Rhizobium genes involved in exopolysaccharide synthesis and effective nodulation. J. Mol. Appl. Genet. 1. 585–596.
Chen H, Batley M, Redmond J W and Rolfe B G 1985 Alteration of the effective nodulation properties of a fast-growing broad host range Rhizobium due to changes in exopolysaccharide synthesis. J. Plant Physiol. 120, 331–349.
Chen H, Gartner E and Rolfe G B 1993 Involvement of genes on a megaplasmid in the acid-tolerant phenotype of Rhizobium leguminosarum biovar trifolii. Appl. Environ. Microbiol. 59, 1058–1064.
Chen H, Gray J X, Nayudu M, Djordjevic M A, Batley M, Redmond J W and Rolfe B G 1988 Five genetic loci involved in the synthesis of acidic exopolysaccharides are closely linked in the genome of Rhizobium sp. strain NGR 234. Mol. Gen. Genet. 212, 310–316.
Ditta G, Stanfield S, Corbin S and Helinski D R 1980 Broad host range DNA cloning system for Gram-negative bacteria: construction of gene bank of Rhizobium meliloti. Proc. Natl. Acad. Sci. USA 77, 7347–7351.
Dixon R, Cannon F and Kondorosi A 1976 Construction of a P plasmid carrying nitrogen fixation genes from Klebsiella pneumonia. Nature (London) 260, 268–271.
Djordjevic S P, Chen H, Batley M, Redmond J W and Rolfe B G 1987 Nitrogen fixation ability of exopolysaccharide synthesis mutants of Rhizobium sp. strain NGR234 and Rhizobium trifolii is restored by the addition of homologous exopolysaccharides. J. Bacteriol. 169, 53–60.
Glazebrook J and Walker G C 1989 A novel exopolysaccharide can function in place of the calcofluor-binding exopolyhsaccharide in nodulation of alfalfa by Rhizobium meliloti. Cell 56, 661–672.
Glucksmann M A, Reuber T L and Walker G C 1993 Genes needed for the modification, polymerization, export, and processing of succinoglycan by Rhizobium melilotii: a model for succinoglycan biosynthesis. J. Bacteriol. 175, 7045–7055.
Gray J A, Zhan H, Levery S B, Battisi L, Rolfe B G and Leight J 1991 Heterologous exopolysaccharide production in Rhizobium sp. strain NGR234 and consequences for nodule development. J. Bacteriol. 173, 3066–3077.
Hotter G S and Scott D B 1991 Exopolysaccharide mutants of Rhizobium loti are fully effective on a determinate nodulating host but are ineffective on an indeterminate nodulating host. J. Bacteriol. 173, 815–859.
Innes R W, Kuempel P L, Plazinski J, Canter-Cremers H, Rolfe B G and Djordjevic M A 1985 Plant factors induce expression of nodulation and host-range genes in Rhizobium trifolii. Mol. Gen. Genet. 201, 426–432.
Kim C-H, Tully R E and Keister D L 1989 Exopolysaccharidedeficient mutants of Rhizobium fredii HH303 which are symbiotocally effective. Appl. Environ. Mocrobiol. 55, 1852–1854.
Leigh J A and Lee C C 1988 Characterization of polysaccharides of Rhizobium meliloti exo mutants that form ineffective nodules. J. Bacteriol. 170, 3327–3332.
Leigh J A, Signer E R and Walker G C 1985 Expolysaccharide-deficient mutants of Rhizobium meliloti that form ineffective nodules. Proc. Natl. Acad. Sci. USA 82, 6231–6235.
Long S R 1989 Rhizobium-legume nodulation: life together in the underground. Cell. 56, 203–214.
Long S A, Signer E R and Walker G C 1988 Genetic analysis of a cluster of genes required for synthesis of the Calcofluor-binding exopolysaccharide of Rhizobium meliloti. J. Bacteriol. 170, 4239–4248.
Rolfe B G, Gresshoff P M and Shine J 1980 Rapid screening for symbiotic mutants of Rhizobium and white clover. Plant Sci. Lett. 19, 277–284.
Scott K F, Hughes J E, Gresshoff P M, Beringer J E, Rolfe B G and Shine J 1982 Molecular cloning of Rhizobium trifolii genes involved in symbiotic nitrogen fixation. J. Mol. Appl. Genet 1, 315–326
Zhan H, Gray J M, Levery S B, Rolfe B G and Leigh J 1990 Functional and evolutionary relatedness of genes for exopolysaccharide synthesis in Rhizobium meliloti and Rhizobium sp. strain NGR234. J. Bacteriol. 172, 5245–5253.
Zhan H, Levery S B, Lee C C and Leigh J 1989 A second exopolysaccharide of Rhizobium meliloti strain SU47 that can function in root nodule invasion. Proc. Natl. Acad. Sci. USA 86, 3055–3059
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Chen, H., Long, BG. & Song, HY. Exopolysaccharide-deficient mutants of Astragali rhizobia are symbiotically effective on Astragalus sinicus, an indeterminate nodulating host. Plant Soil 179, 217–221 (1996). https://doi.org/10.1007/BF00009331
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00009331