Strain-Specific Inhibition of
            <i>nod</i>
            Gene Induction in
            <i>Bradyrhizobium japonicum</i>
            by Flavonoid Compounds

Kosslak, Renee M.; Joshi, Rita S.; Bowen, Ben; Paaren, Herbert E.; Appelbaum, Edward R.

doi:10.1128/aem.56.5.1333-1341.1990

Cited by 58 publications

(12 citation statements)

References 37 publications

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“…This second wave of flavonoids leads to an increased nod gene-inducing activity, by as much as 10-fold, as detected for white clover (207), vetch (268), soybean (223), bean (39), Lotus species (35), and alfalfa (38). In several cases, flavonoids without inducing properties have been shown to inhibit nod gene activation by effective inducers (54,73,101,141,186). The antiinducers usually have similar structures to those of the inducers, and inhibition can be overcome by increasing the concentration of the inducers (186).…”

Section: Regulatory Nod Genes As Host Range Determinants Nodd Genementioning

confidence: 91%

The Rhizobium-plant symbiosis.

Rhijn¹,

Vanderleyden²

1995

Microbiological Reviews

343

144

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Section: Regulatory Nod Genes As Host Range Determinants Nodd Genementioning

confidence: 91%

The Rhizobium-plant symbiosis.

Rhijn¹,

Vanderleyden²

1995

Microbiological Reviews

343

144

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“…In soybean, isoflavones (e.g. genistein and daidzein), a group of flavonoid compounds that are found almost exclusively in legumes, were shown to be the primary inducers of Bradyrhizobium japonicum nod gene expression (Banfalvi et al, 1988;Kosslak et al, 1990;Loh et al, 1994;Smit et al, 1992). In addition to isoflavones, a few other flavonoid compounds, including isoliquiritigenin, the chalcone precursor of daidzein, were also shown to induce nod gene expression in B. japonicum (Kape et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Endogenous isoflavones are essential for the establishment of symbiosis between soybean and Bradyrhizobium japonicum

2006

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SummaryLegume iso/flavonoids have been implicated in the nodulation process, but questions remain as to their specific role(s), and no unequivocal evidence exists showing that these compounds are essential for nodulation. Two hypotheses suggest that the primary role of iso/flavonoids is their ability to induce rhizobial nod gene expression and/or their ability to modulate internal root auxin concentrations. The present work provides direct, genetic evidence that isoflavones are essential for nodulation of soybean roots because of their ability to induce the nodulation genes of Bradyrhizobium japonicum. Expression of isoflavone synthase (IFS), a key enzyme in the biosynthesis of isoflavones, is specifically induced by B. japonicum. When IFS was silenced using RNA interference in soybean hairy root composite plants, these plants had severely reduced nodulation. Surprisingly, pre-treatment of B. japonicum or exogenous application to the root system of either of the major soybean isoflavones, daidzein or genistein, failed to restore normal nodulation. Silencing of chalcone reductase led to very low levels of daidzein and increased levels of genistein, but did not affect nodulation, suggesting that the endogenous production of genistein was sufficient to support nodulation. Consistent with a role for isoflavones as endogenous regulators of auxin transport in soybean roots, silencing of IFS resulted in altered auxin-inducible gene expression and auxin transport. However, use of a genistein-hypersensitive B. japonicum strain or purified B. japonicum Nod signals rescued normal nodulation in IFS-silenced roots, indicating that the ability of isoflavones to modulate auxin transport is not essential to nodulation.

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“…Rhizobia differ in their acceptance of flavonoids as inducers, as can be deduced from Table 3. Moreover, flavonoids can also repress nod gene induction [97][98][99][100][101], e.g., daidzein and genisrein, both being strong inducers in B. japonicum (Table 3), are potent inhibitors of gene expression in R. leguminosarum bv. viciae [99] and R. meliloti [102].…”

Section: Nodulation Genes Are Activated By Nodd In the Presence Of A mentioning

confidence: 99%

Regulation and function of rhizobial nodulation genes

GOTTFERT¹

1993

FEMS Microbiology Letters

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Azorhizobium [217] Bradyrhizobiurn [218] ¢ Rhizobium [219] d A. caulinodans [217] B. japonicurn [218] Bradyrhizobium sp. ( Parasponia ) R. fredii [220] ( Sinorhizobium fredii ) R. galegae [222] R. leguminosarum biovar phaseoli [223] biovar trifolii [223] biovar viciae [223] R. loti [224] R. meliloti [219] d R. tropici ~ [225] Sinorhizobium [24] g S. fredii [24] R. japonicum (slow growing strains) [219] d R. japonicum (fast growing strains) [221] R. phaseoli [219] a R. trifolii [219] d R. legurninosarum [219] d R. leguminosarum biovar phaseoli (type II strains) [225] d Sesbania Glycine, ~gna Glycine, ~gna Galega Phaseolus Trifolium Pisum, l, qcia Lotus, Lupinus Melilotus, Medicago Phaseolus, Leucaena Rhizobium sp. strain Leucaena, NGR234 [226] f Macroptilium, Vigna R. fredii [220] Glycine a Only species relevant for this review are listed. b The list of host plants is not complete. The host range may extend beyond that given here and may differ among species of a genus. c For Bradyrhizobium strains other than B. ]aponicum it was suggested that they be referred to as Bradyrhizobium sp. with the name of the host plant in parentheses immediately following [218], e.g., Bradyrhizobium sp. (Parasponia). d And further references therein. The older designation was used throughout this review.f Probably, this strain belongs to R. fredii [25]. In this review no differentiation is made between the almost isogenic strains Rhizobiurn sp. strain NGR234 and strain MPIK3030 [227].g See text for a recent dispute. 42tractant [48]. The nodulation genes are probably not involved in this chemotactic response [49].Chemotaxis towards nod gene-inducing flavonoids was also reported for Rhizobium leguminosarum strains [33,50]. In this case, the symbiotic plasmid, which carries all known nod genes, was beneficial, but not essential, for chemotaxis [50]. In contrast, none or only a very weak chemotaxis towards inducers of nod gene transcription was detected in B. japonicum [34,40]. Bj [243]; NGR234 [244]; Rlbt [245]; Rm [107] Bj [115,243]; Rlbt [98]; Rlbv [99]; Rm [47] Rlbv [99] Rm [102] Rlbv [99]; Rm [47] Rm [246] Rlbp [247] Rlbp [247] Rlbp [247] Ac [248]; Rlbt [98]; Rm [107] Ac [75]; NGR234 [244]; Rlbp [81,249]; Rlbv [99] Rlbv [250] Rlbv [99] Rlbv [250] Rlbp [249]; Rlbv [99] Rlbp [247] Rlbp [247] Rlbp [247] Rm [102] Bj [115,243,251]; NGR234 [244] Bj [115,243]; Rlbp [81.249] Bj [243] Bj [243] Bj [1151 Bj [243] Bj [85]; Rlbt [92]; Rlbv [92]; Rm [107] Only the most potent inducers are listed. Additional inducers are recorded in the literature cited. b Abbreviations for rhizobia: Ac, A. caulinodans; Bj, B. japonicurn; NGR234, Rhizobium sp. strain NGR234; Rlbp, R. legurninosarum by. phaseoli; Rlbt, R. leguminosarum bv. trifolii; Rlbv, R. leguminosarum bv. L,iciae; Rm, R. meliloti.

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Strain-Specific Inhibition of nod Gene Induction in Bradyrhizobium japonicum by Flavonoid Compounds

Cited by 58 publications

References 37 publications

The Rhizobium-plant symbiosis.

The Rhizobium-plant symbiosis.

Endogenous isoflavones are essential for the establishment of symbiosis between soybean and Bradyrhizobium japonicum

Regulation and function of rhizobial nodulation genes

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