title: Flavonoids induce germination of basidiospores of the ectomycorrhizal fungus Suillus bovinus.
abstract: Under laboratory conditions, spores of ectomycorrhizal fungi usually germinate very poorly or not at all. In a previous study, we showed that spores of the ectomycorrhizal fungus Suillus bovinus germinated through the combination of activated charcoal treatment of media and co-culture with seedlings of Pinus densiflora, which suggested that some substances contained in root exudates induced the germination. Among the compounds reported from root exudates, flavonoids have been elucidated to play various and substantial roles in plant-microbe interactions; we therefore investigated the effects of flavonoids on basidiospore germination of S. bovinus by the diffusion gradient assay on water agar plates pretreated with charcoal powder. Seven out of the 11 flavonoids tested, hesperidin, morin, rutin, quercitrin, naringenin, genistein, and chrysin, had greater effects than controls, whereas flavone, biochanin A, luteolin, and quercetin showed no positive effects. The effective concentration presumably corresponded to several micromolar levels, which was equivalent to those effective for pollen development, nod gene induction, and spore germination of F. solani f. sp. pisi and AM fungi. The results suggest that flavonoids play a role as signaling molecules in symbiotic relationships between woody plants and ectomycorrhizal fungi.
authors.affiliation: Laboratory of Forest Botany, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan. kiku@fr.a.u-tokyo.ac.jp.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Kikuchi
authors.affiliation: Laboratory of Forest Botany, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Norihisa
authors.initials: N
authors.lastname: Matsushita
authors.affiliation: Laboratory of Forest Microbiology, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa, 252-8510, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Laboratory of Forest Botany, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Taizo
authors.initials: T
authors.lastname: Hogetsu
mesh_terms: D005419:Flavonoids / Q000494:pharmacology*; D038821:Mycorrhizae / Q000187:drug effects*; D028223:Pinus / Q000382:microbiology; D013172:Spores, Fungal / Q000187:drug effects* / Q000502:physiology
chemical_list: D005419:Flavonoids