Plant factors induce expression of nodulation and host-range genes in Rhizobium trifolii

Innes, Roger W.; Kuempel, Peter L.; Plazinski, Jacek; Canter-Cremers, Hayo; Rolfe, Barry G.; Djordjevic, Michael A.

doi:10.1007/bf00331334

Cited by 143 publications

(82 citation statements)

References 26 publications

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“…Establishing the structure of the parental LPS will greatly facilitate our analysis of the structural alterations, if any, which are present in the various mutants. It has recently been shown, using Mu-lac insertion mutants, that the nod ABC genes as well as other nodulation genes require induction by a factor in the host root exudate (13). Thus, it is very important to reexamine the LPSs from strains which have been grown under conditions that are known to induce these genes.…”

Section: Abstracirmentioning

confidence: 99%

The Isolation and Partial Characterization of the Lipopolysaccharides from Several Rhizobium trifolii Mutants Affected in Root Hair Infection

Carlson¹,

Shatters²,

Duh³

et al. 1987

Plant Physiol.

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ABSTRACIrThe lipopolysaccharides (LPSs) from Rhizobium trifolii ANU843 and several transposon (Tn5) symbiotic mutants derived from ANU843 were isolated and partially characterized. The mutant strains are unable to induce normal root hair curling (Hac-phenotype) or nodulation (Nodphenotype) in clover plants. The LPSs from the parent and mutants are very similar in composition. Analysis by PAGE shows that the LPSs consist of higher and lower molecular weight forms. The higher molecular weight form of the LPSs exists in several aggregation states when PAGE is done in 0.1% SDS but collapses into a single band when PAGE is done in 0.5% SDS. Mild acid hydrolysis of all the LPSs releases two polysaccharides, PS1 and PS2. Immunoblots of the PAGE gels and enzyme linked immunosorbant assay inhibition assays show that the PS1 fractions contain the immunodominant sites of the LPSs and that these sites are present in the higher molecular weight form of the LPSs. All the PS1 fractions contain methylated sugars, 2-amino-2,6-dideoxyhexose, heptose, glucuronic acid, and 2-keto-3-deoxyoctonic acid (KDO). All the PS2 fractions contain galacturonic acid, mannose, galactose, and KDO. The PS2 fractions have a molecular weight of about 700. The KDO is present at the reducing end of both the PS1 and the PS2 fractions. The PSI and PS2 fractions from the mutants contain more glucose than these fractions from the parent. The LPS from a deletion mutant contains less acyl groups than the other LPSs. Immunoblots of the LPSs show that the parent and nod A mutant LPSs contain an additional antigenic band which is not observed in the other LPSs.Rhizobia are gram-negative bacteria which form a nitrogenfixing symbiotic relationship with legume plants. As gram-negative bacteria they have the usual surface polysaccharides consisting of EPSs,6 CPSs, and LPSs. All of these molecules have been 'Funded by a grant from the National Science Foundation (DCB8406697).

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Section: Abstracirmentioning

confidence: 99%

The Isolation and Partial Characterization of the Lipopolysaccharides from Several Rhizobium trifolii Mutants Affected in Root Hair Infection

Carlson¹,

Shatters²,

Duh³

et al. 1987

Plant Physiol.

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“…In three agronomically important Rhizobium/legume associations, R. trifolii/clover, R. meliloti/alfalfa, and R. leguminosarum/pea, important bacterial nodulation genes (1)(2)(3)(4) and plant compounds that induce them (5-7) have been identified. In these associations flavones (5)(6)(7) or flavanones (7) have been found to induce the nodABC genes, as well as other nod genes involved in host specificity (1). Isoflavones have been found to inhibit the induction of nodABC in R. leguminosarum (7).…”

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confidence: 99%

Induction of Bradyrhizobium japonicum common nod genes by isoflavones isolated from Glycine max

Kosslak¹,

Bookland²,

Barkei³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

375

225

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The early events in legume nodulation by Rhizobium spp. involve a conserved gene cluster known as the common nod region. A broad-host-range plasmid (pEA2-21) containing a Bradyrhizobium japonicum nodDABC-acZ translational fusion was constructed and used to monitor nod gene expression in response to soybean root extract. Two inducing compounds were isolated and identified. Analysis using ultraviolet absorption spectra, proton nuclear magnetic resonance, and mass spectrometry showed that the two inducers were 4',7-dihydroxyisoflavone (daidzein) and 4',5,7-trihydroxyisoflavone (genistein). Induction was also seen with some, but not all, of the flavonoid compounds that induce nod genes in fast-growing Rhizobium strains that nodulate clover, alfalfa, or peas. When pEA2-21 was introduced into Rhizobium trifohii, it was inducible by flavones but not by daidzein and genistein. In Rhizobium fredii, pEA2-21 was induced by isoflavones and flavones. Thus, the specificity of induction appears to be influenced by the host-strain genome.Members of the bacterial genus Rhizobium form symbiotic associations with leguminous plants that result in the formation of nitrogen-fixing root nodules. In three agronomically important Rhizobium/legume associations, R. trifolii/clover, R. meliloti/alfalfa, and R. leguminosarum/pea, important bacterial nodulation genes (1-4) and plant compounds that induce them (5-7) have been identified. In these associations flavones (5-7) or flavanones (7) have been found to induce the nodABC genes, as well as other nod genes involved in host specificity (1). Isoflavones have been found to inhibit the induction of nodABC in R. leguminosarum (7).The Bradyrhizobium japonicum/soybean symbiosis is of considerable agricultural importance. In contrast to Rhizobium spp., Bradyrhizobium species are slow-growing (8), nitrogen-fixation and nodulation genes are located on the chromosome (9) and not on plasmids (10)(11)(12), and less is known about the genetic requirements for nodulation (13)(14)(15). In particular, the compounds produced by the soybean host that interact with the common nod genes have not been characterized.In this study, a nodABC-lacZ translational fusion was used to monitor nod gene expression in B. japonicum in response to soybean root extract. Two major components from soybeans (Glycine max cv. Williams) were isolated that induced the expression of the nodABC-lacZ fusion when it was present in the soybean-nodulating bacteria B. japonicum and Rhizobium fredii, but not when it was present in R. trifolii. MATERIALS AND METHODSStrains and Plasmids. Standard procedures (16) were used for DNA manipulations. A HindIII fragment containing the nod region of B. japonicum USDA 123 was cloned in both orientations into the single HindIII site of plC19R (17). BamHI-Bgl II fragments containing the nod genes and flanking polylinker sequences were then cloned into the BamHI site of the broad-host-range vector pGD926 (18) resulting in pEA2-21 and pEA4-10 (Fig. 1) (19) agar and germinated for 3 days in the d...

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“…'activation des genes de Ia nodulation de Ia bacterie est devenu evident seulement avec I 'utilisation d'un gene marquem (lacZ) dont Ia transcription peut etre detectee par un test colorimetrique rapide (Mulligan et Long, 1985). La fusion du gene lacZ de Escherichia coli avec les genes de nodulation de Rhizobium a ainsi permis d'analyser l'activite inductrice des flavonoldes presents au niveau des graines et dans Ies exsudats racinaires (Innes et at., 1985 ;Rossen et al, 1985). Le mecanisme precis de !…”

Section: -Les Genes Commonsunclassified

Importance des composés phénoliques dans les interactions entre plantes et microorganismes: exemple des relationsRhizobium/légumineuses

Cleyet-Marel

Rome

Salducci

et al. 1996

Acta Botanica Gallica

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Plant factors induce expression of nodulation and host-range genes in Rhizobium trifolii

Cited by 143 publications

References 26 publications

The Isolation and Partial Characterization of the Lipopolysaccharides from Several Rhizobium trifolii Mutants Affected in Root Hair Infection

The Isolation and Partial Characterization of the Lipopolysaccharides from Several Rhizobium trifolii Mutants Affected in Root Hair Infection

Induction of Bradyrhizobium japonicum common nod genes by isoflavones isolated from Glycine max

Importance des composés phénoliques dans les interactions entre plantes et microorganismes: exemple des relationsRhizobium/légumineuses

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