title: Strigolactones stimulate arbuscular mycorrhizal fungi by activating mitochondria.
abstract: The association of arbuscular mycorrhizal (AM) fungi with plant roots is the oldest and ecologically most important symbiotic relationship between higher plants and microorganisms, yet the mechanism by which these fungi detect the presence of a plant host is poorly understood. Previous studies have shown that roots secrete a branching factor (BF) that strongly stimulates branching of hyphae during germination of the spores of AM fungi. In the BF of Lotus, a strigolactone was found to be the active molecule. Strigolactones are known as germination stimulants of the parasitic plants Striga and Orobanche. In this paper, we show that the BF of a monocotyledonous plant, Sorghum, also contains a strigolactone. Strigolactones strongly and rapidly stimulated cell proliferation of the AM fungus Gigaspora rosea at concentrations as low as 10(-13) M. This effect was not found with other sesquiterperne lactones known as germination stimulants of parasitic weeds. Within 1 h of treatment, the density of mitochondria in the fungal cells increased, and their shape and movement changed dramatically. Strigolactones stimulated spore germination of two other phylogenetically distant AM fungi, Glomus intraradices and Gl. claroideum. This was also associated with a rapid increase of mitochondrial density and respiration as shown with Gl. intraradices. We conclude that strigolactones are important rhizospheric plant signals involved in stimulating both the pre-symbiotic growth of AM fungi and the germination of parasitic plants.
authors.affiliation: UMR 5546, Pôle de Biotechnologies Végétales, Castanet-Tolosan, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Besserer
authors.forename: Virginie
authors.initials: V
authors.lastname: Puech-Pagès
authors.forename: Patrick
authors.initials: P
authors.lastname: Kiefer
authors.forename: Victoria
authors.initials: V
authors.lastname: Gomez-Roldan
authors.forename: Alain
authors.initials: A
authors.lastname: Jauneau
authors.forename: Sébastien
authors.initials: S
authors.lastname: Roy
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Portais
authors.forename: Christophe
authors.initials: C
authors.lastname: Roux
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bécard
authors.forename: Nathalie
authors.initials: N
authors.lastname: Séjalon-Delmas
mesh_terms: D018552:Daucus carota / Q000737:chemistry; D005658:Fungi / Q000254:growth & development; D018525:Germination; D025301:Hyphae / Q000187:drug effects / Q000254:growth & development; D007783:Lactones / Q000032:analysis / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D038821:Mycorrhizae / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D031670:Orobanchaceae / Q000254:growth & development; D018517:Plant Roots / Q000737:chemistry*; D012639:Seeds / Q000254:growth & development; D012717:Sesquiterpenes / Q000032:analysis / Q000494:pharmacology*; D045868:Sorghum / Q000737:chemistry; D013172:Spores, Fungal / Q000502:physiology
chemical_list: D007783:Lactones; D012717:Sesquiterpenes; C485199:sorgolactone