title: Differential morphogenesis of the extraradical mycelium of an arbuscular mycorrhizal fungus grown monoxenically on spatially heterogeneous culture media.
abstract: A new in vitro experimental system was developed to study the morphogenesis of discrete regions of a single extraradical mycelium of the arbuscular mycorrhizal (AM) fungus Glomus intraradices, growing simultaneously in six different agar-based media. The media were (i) unamended water agar (WA), (ii) WA+PO(4)(3-) (PO(4)(3-)), (iii) WA+NO(3)(-) (NO(3)(-)), (iv) WA+NH(4)(+) (NH(4)(+)), (v) WA+NH(4)(+)+MES (NH(4)(+)+MES) and (vi) minimal medium (M, complete nutrients). Each medium was amended with the pH indicator bromocresol purple. The extraradical mycelium of the fungus showed between-treatment differences in morphogenesis, architecture, formation of branched absorbing structures (BAS) and sporulation. Extraradical hyphae that developed in WA or PO(4)(3-) compartments exhibited an economic development pattern, in which runner hyphae radially extended the external colony. Extraradical hyphal growth in the NO(3)(-) compartments was characterized by increased formation of runner hyphae, BAS and spores and an alkalinization of the medium. In the two NH(4)(+)-amended media (NH(4)(+), NH(4)(+)+MES), sporulation was suppressed and considerable morphological changes were noted. These results show the plasticity of G. intraradices that lets it efficiently exploit an heterogeneous substrate.
authors.affiliation: Centro de Investigaciones sobre Desertificación (CSIC/ UV/GV), Camí de la Marjal s/n, 46470 Albal (Valencia), Spain.
authors.forename: Bert
authors.initials: B
authors.lastname: Bago
authors.forename: Custodia
authors.initials: C
authors.lastname: Cano
authors.forename: Concepción
authors.initials: C
authors.lastname: Azcón-Aguilar
authors.forename: Julie
authors.initials: J
authors.lastname: Samson
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Coughlan
authors.forename: Yves
authors.initials: Y
authors.lastname: Piché