title: Development of extraradical mycelium of Scutellospora reticulata under root-organ culture: spore production and function of auxiliary cells.
abstract: The development of the extraradical mycelium and auxiliary cells and spore production of Scutellospora reticulata in association with Ri T-DNA transformed carrot roots was followed under root-organ culture conditions. Extraradical mycelium development followed classical lag-exponential-plateau phases, with an additional late decline phase in number of auxiliary cells. Spore production started in parallel with a critical extraradical mycelium biomass produced, continued long after root growth ceased and during the late decline in auxiliary cells number. Isolated auxiliary cells were shown to exhibit hyphal re-growth, but not root colonization, either in situ or in vitro. These results showed that root and extraradical mycelium development were intimately associated in a sequence where both grew together during active root growth, followed during root aging by a period in which only the fungus developed. Spore production appeared dependent on a critical extraradical mycelium biomass and on the re-allocation of resources from both the intraradical mycelium and the auxiliary cells via the hyphal network.
authors.affiliation: Université Catholique de Louvain, Mycothèque de l'Université catholique de Louvain, Unité de microbiologie, 3 Place Croix du Sud, 1348 Louvain-La-Neuve, Belgium. declerck@mbla.ucl.ac.be
authors.forename: Stéphane
authors.initials: S
authors.lastname: Declerck
authors.forename: Dimitri
authors.initials: D
authors.lastname: D'Or
authors.forename: Céline
authors.initials: C
authors.lastname: Bivort
authors.forename: Francisco A
authors.initials: FA
authors.lastname: de Souza
mesh_terms: D025282:Mycelium / Q000254:growth & development*; D038821:Mycorrhizae / Q000254:growth & development*; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology*; D013172:Spores, Fungal / Q000502:physiology