Biosynthesis, elicitation and biological activity of isoflavonoid phytoalexins

Smith, David A.; Banks, Stephen W.

doi:10.1016/s0031-9422(00)81542-3

Cited by 135 publications

(55 citation statements)

References 164 publications

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“…4). A 5-flM treatment in the experiment reported in Figure 4 did not increase growth rate above that for 2.5 uM, and other tests with saturating concentrations of luteolin (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) Mm in this medium, as determined by HPLC analysis) never increased the growth rate over the enhancement evident with 1 to 5 AM treatments in various experiments. Growth rates calculated for data in Figure 4 …”

Section: Biological Activity Of Flavonoidsmentioning

confidence: 56%

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Flavonoids Released Naturally from Alfalfa Seeds Enhance Growth Rate of Rhizobium meliloti

Hartwig¹,

Joseph²,

Phillips³

1991

Plant Physiol.

195

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Alfalfa (Medicago sativa L.) releases different flavonoids from seeds and roots. Imbibing seeds discharge 3',4',5,7-substituted flavonoids; roots exude 5-deoxy molecules. Many, but not all, of these flavonoids induce nodulation (nod) genes in Rhizobium meliloti. The dominant flavonoid released from alfalfa seeds is identified here as quercetin-3-O-galactoside, a molecule that does not induce nod genes. Low concentrations (1-10 micromolar) of this compound, as well as luteolin-7-O-glucoside, another major flavonoid released from germinating seeds, and the aglycones, quercetin and luteolin, increase growth rate of R. meliloti in a defined minimal medium. Tests show that the 5,7-dihydroxyl substitution pattern on those molecules was primarily responsible for the growth effect, thus explaining how 5-deoxy flavonoids in root exudates fail to enhance growth of R. meliloti. Luteolin increases growth by a mechanism separate from its capacity to induce rhizobial nod genes, because it still enhanced growth rate of R. meliloti lacking functional copies of the three known nodD genes. Quercetin and luteolin also increased growth rate of Pseudomonas putida. They had no effect on growth rate of Bacillus subtilis or Agrobacterium tumefaciens, but they slowed growth of two fungal pathogens of alfalfa. These results suggest that alfalfa can create ecochemical zones for controlling soil microbes by releasing structurally different flavonoids from seeds and roots.

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Section: Biological Activity Of Flavonoidsmentioning

confidence: 56%

“…It is well known, of course, that isoflavonoid molecules often function as phytoalexins and inhibit microbial growth (24). The mechanism by which flavones with 5,7-dihydroxyl substitutions promote microbial growth is not apparent from data presently available.…”

Section: Discussionmentioning

confidence: 99%

Flavonoids Released Naturally from Alfalfa Seeds Enhance Growth Rate of Rhizobium meliloti

Hartwig¹,

Joseph²,

Phillips³

1991

Plant Physiol.

195

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“…In particular, leguminous plants produce isoflavonoid phytoalexins as defense substances against phytopathogenic microorganisms [2]. An enzyme that catalyzes the rearrangement reaction of flavanone is the first enzyme of isoflavonoid biosynthesis which branches from the general flavonoid pathway [3-51.…”

Section: Introduction 2 Materials and Methodsmentioning

confidence: 99%

Reaction mechamism of oxidative rearrangement of flavanone in isoflavone biosynthesis

et al. 1990

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Microsomes that were prepared from elicitor‐treated Pueraria lobata cell cultures catalyzed the conversion of liquiritigenin, a flavanone, into daidzein, an isoflavone. The reaction was resolved into two steps. 2, 7, 4'‐Trihydroxyisoflavanone was formed as a major product when liquiritigenin was incubated with carefully washed microsomes in the presence of NADPH. The structure of 2, 7, 4'‐trihydroxyisoflavanone was confirmed by mass and 1H NMR spectroscopies. The enzyme responsible for this rearrangement reaction is a cytochrome P‐450‐dependent monooxygenase. Upon treatment with a soluble enzyme fraction 2, 7, 4'‐trihydroxyisoflavone yielded daidzein quantitatively. The incorporation of 18O from 18O2 into the 2‐hydroxy group of 2, 7, 4'‐trihydroxyisoflavanone was demonstrated by the shift of molecular ion in its mass spectrum. Based on these observations a new reaction mechanism, hydroxylation associated with 1,2‐migration, is proposed for the oxidative rearrangement reaction catalyzed by the cytochrome P‐450 enzyme of Pueraria lobata.

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“…(Ingham, 1982;Smith et Banks, 1986). Aussi, Ingham et Harborne (1976) proposent-ils l'utilisation de ces méta-bolites secondaires pour une nouvelle approche de la systématique des végétaux supérieurs (Ingham, 1982;Stoessl, 1983).…”

Section: Déterminisme Génétiqueunclassified

“…La plupart des espèces ne produisent que rarement des phytoalexines appartenant à plus de 2 ou 3 groupes de structure chimique différente et, dans une même classe de composés, les structures des phytoalexines produites sont, en général, très proches (Mansfield, 1983). Cependant, des composés présentant une même unité structurale (stilbènes par exemple) peuvent être détectés chez des espèces végétales très éloignées (Stoessl, 1983;Brooks et Watson, 1985 (Smith, 1982;Smith et Banks, 1986;Yoshikawa et al, 1987). Il existe toutefois des exemples où une action sur la respiration cellulaire est signalée (Yoshikawa et al, 1987).…”

Section: Déterminisme Génétiqueunclassified

Les phytoalexines et leur intervention dans la résistance hypersensible aux champignons phytopathogènes

Rouxel¹

1989

Agronomie

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Biosynthesis, elicitation and biological activity of isoflavonoid phytoalexins

Cited by 135 publications

References 164 publications

Flavonoids Released Naturally from Alfalfa Seeds Enhance Growth Rate of Rhizobium meliloti

Flavonoids Released Naturally from Alfalfa Seeds Enhance Growth Rate of Rhizobium meliloti

Reaction mechamism of oxidative rearrangement of flavanone in isoflavone biosynthesis

Les phytoalexines et leur intervention dans la résistance hypersensible aux champignons phytopathogènes

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