Isoflavone precursors of the pterocarpan phytoalexin maackiain in Trifolium pratense

Dewick, Paul M.; Ward, David

doi:10.1016/s0031-9422(00)88687-2

Cited by 38 publications

(11 citation statements)

References 22 publications

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“…2'-Hydroxylation of the B ring is believed to occur at the isoflavonoid stage; however, phytoalexins such as pisatin (XI) and maackiain (X) also possess a 4',5'-methylene dioxy substituent on ring B (see Section II.B.4). The initial oxygenation pattern (4',5'-dihydroxy) may arise either at the level of the CbC3 precursor or, as suggested by radiolabeling experiments (146,147), at the CIS stage; in the first case, the involvement of a CoA ligase with activity toward caffeic acid (XXII) would be predicted. Such substrate specificity would also be reflected in the next enzyme of the pathway, the chalcone synthase.…”

Section: Mg"mentioning

confidence: 97%

“…Radiolabeling experiments in Trifolium prutense (146) have demonstrated the formation of maackiain via 7,3'-dihydroxy4'-methoxyioflavone (XLVI), and the possibility of a metabolic grid in which 2'-hydroxylation occurred either before or after the cyclization of the methylene-dioxy ring was suggested (146) (Scheme 11). Both XLVI and 7-hydroxy,3',4'-methylene-dioxy isoflavone (XLVII) have been isolated from T. prufense (211).…”

Section: Conversion Of Isoflavones To Pterocarpans and Furthermentioning

confidence: 99%

See 1 more Smart Citation

Phytoalexins: Enzymology and Molecular Biology

Dixon¹,

Dey²,

Lamb

1983

Advances in Enzymology - And Related Areas of Molecular Biology

220

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Section: Mg"mentioning

confidence: 97%

Section: Conversion Of Isoflavones To Pterocarpans and Furthermentioning

confidence: 99%

Phytoalexins: Enzymology and Molecular Biology

Dixon¹,

Dey²,

Lamb

1983

Advances in Enzymology - And Related Areas of Molecular Biology

220

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“…Complex isoflavonoid derivatives such as the rotenoids rotenone, deguelin, and amorphigenin from Amorpha , Lonchocarpus , Derris , and Tephrosia species possess insecticidal and parasiticidal properties (Lambert et al ., 1993; Nicholas et al ., 1985). Maackiain (Figure 1), which accumulates along with medicarpin (the major phytoalexin in Medicago species) in red clover ( Trifolium pratense ), subterranean clover ( T. subterraneum ), and chickpea ( Cicer arietinum ; Dewick and Ward, 1978; Higgins, 1972; Ingham, 1982), has recently been shown to have larvicidal activity against caterpillars of Heliocoverpa armigera that attack chickpea (Simmonds and Stevenson, 2001).…”

Section: Introductionmentioning

confidence: 99%

Regiospecific hydroxylation of isoflavones by cytochrome P450 81E enzymes from Medicago truncatula

et al. 2003

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SummaryMining of Medicago truncatula EST databases and screening of a root cDNA library led to the identi®cation of three cytochrome P450 81E subfamily members. Two were functionally characterized by expression in yeast. The recombinant enzymes in yeast microsomes utilized the same iso¯avone substrates, but produced different products hydroxylated at the 2 H and/or 3 H positions of the B-ring. When transiently expressed in alfalfa leaves, green¯uorescent protein (GFP) fusions of the iso¯avone 2 H -and 3 H -hydroxylases localized to the endoplasmic reticulum. The iso¯avone 2 H -hydroxylase was functional when expressed in Arabidopsis. Differential tissue-speci®c and biotic/abiotic stress-dependent expression patterns were observed for the iso¯avone 2 H -hydroxylase and 3 H -hydroxylase genes, suggesting differential involvement of 2 H -and 3 H -hydroxylated iso¯avonoids in pathogen defense and insect-induced responses, respectively, in Medicago.

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“…Published procedures were used to obtain (+)pisatin (21), (+)-and (-)maackiain (20), (-)sophorol (8) and DMI (9). Ethanol [3H]Maackiain was purified by TLC as described below.…”

Section: Materials and Methods Chemicalsmentioning

confidence: 99%

Biosynthesis of the Phytoalexin Pisatin

Preisig¹,

Bell²,

Sun³

et al. 1990

Plant Physiol.

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NADPH-dependent reduction of 2',7-dihydroxy-4',5'-methylenedioxyisoflavone to the isoflavanone sophorol, a proposed intermediate step in pisatin biosynthesis, was detected in extracts of Pisum sativum. This isoflavone reductase activity was inducible by treatment of pea seedlings with CuCI2. The timing of induction coincided with that of the 6a-hydroxymaackiain 3-0-methyltransferase, which catalyzes the terminal biosynthetic step. Neither enzyme was light inducible. Further NADPH-dependent metabolism of sophorol by extracts of CuCI2-treated seedlings was also observed; three products were radiolabeled when [3H]sophorol was the substrate, one of which is tentatively identified as maackiain.The pterocarpan (+)pisatin is the major phytoalexin synthesized by Pisum sativum. In the disease ofP. sativum caused by Nectria haematococca, genetic studies on the fungus suggest that the ability of fungal isolates to detoxify pisatin is necessary for high virulence on pea plants ( 19). These results imply that pisatin is an effective barrier to nondetoxifying fungal isolates and is important in the defense of pea against microbial attack.Isoflavonoid phytoalexin synthesis has been the subject of much recent study of the regulation of gene expression in plants (12). Biochemical characterization of the late steps in the pisatin pathway is a prerequisite for this type of study on pea. Banks and Dewick (1) proposed a biosynthetic pathway for (+)pisatin and (-)maackiain, a minor phytoalexin of pea (16) (Fig.

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Isoflavone precursors of the pterocarpan phytoalexin maackiain in Trifolium pratense

Cited by 38 publications

References 22 publications

Phytoalexins: Enzymology and Molecular Biology

Phytoalexins: Enzymology and Molecular Biology

Regiospecific hydroxylation of isoflavones by cytochrome P450 81E enzymes from Medicago truncatula

Biosynthesis of the Phytoalexin Pisatin

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