title: Lupin pyranoisoflavones inhibiting hyphal development in arbuscular mycorrhizal fungi.
abstract: White lupin (Lupinus albus L.), a non-host plant for arbuscular mycorrhizal (AM) fungi in the typically mycotrophic family Fabaceae, has been investigated for root metabolites that inhibit hyphal development in AM fungi. Four known pyranoisoflavones, licoisoflavone B (1), sophoraisoflavone A (2), alpinumisoflavone (3) and 3'-hydroxy-4'-O-methylalpinumisoflavone (4), together with three previously unknown pyranoisoflavones, lupindipyranoisoflavone A (5), 10'-hydroxylicoisoflavone B (6) and 10'-hydroxysophoraisoflavone A (7) were isolated from the root exudates of white lupin as an inhibitor of germ tube growth in the AM fungus Gigaspora margarita. Pyranoisoflavones 1, 2 and 3 strongly inhibited germ tube growth at 0.63, 1.25 and 0.63 μg/disc, respectively. The remaining compounds 4-7 were either moderate or weak inhibitors that inhibited germ tube growth at concentrations higher than 10 μg/disc. Licoisoflavone B (1) and sophoraisoflavone A (2) completely inhibited hyphal branching induced by a lupin strigolactone, orobanchyl acetate, in G. margarita at 0.16 and 0.63 μg/disc, respectively.
authors.affiliation: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan. akiyama@biochem.osakafu-u.ac.jp
authors.forename: Kohki
authors.initials: K
authors.lastname: Akiyama
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Tanigawa
authors.forename: Takanori
authors.initials: T
authors.lastname: Kashihara
authors.forename: Hideo
authors.initials: H
authors.lastname: Hayashi
mesh_terms: D007529:Isoflavones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D031297:Lupinus / Q000737:chemistry* / Q000382:microbiology; D015394:Molecular Structure; D038821:Mycorrhizae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology
chemical_list: C507553:4'-O-methylalpinumisoflavone; D007529:Isoflavones; C446245:sophoraisoflavone A; C446244:licoisoflavone B