title: Biosynthesis and Secretion of Indole-3-Acetic Acid and Its Morphological Effects on Tricholoma vaccinum-Spruce Ectomycorrhiza.
abstract: Fungus-derived indole-3-acetic acid (IAA), which is involved in development of ectomycorrhiza, affects both partners, i.e., the tree and the fungus. The biosynthesis pathway, excretion from fungal hyphae, the induction of branching in fungal cultures, and enhanced Hartig net formation in mycorrhiza were shown. Gene expression studies, incorporation of labeled compounds into IAA, heterologous expression of a transporter, and bioinformatics were applied to study the effect of IAA on fungal morphogenesis and on ectomycorrhiza. Tricholoma vaccinum produces IAA from tryptophan via indole-3-pyruvate, with the last step of this biosynthetic pathway being catalyzed by an aldehyde dehydrogenase. The gene ald1 was found to be highly expressed in ectomycorrhiza and induced by indole-3-acetaldehyde. The export of IAA from fungal cells is supported by the multidrug and toxic extrusion (MATE) transporter Mte1 found in T. vaccinum. The addition of IAA and its precursors induced elongated cells and hyphal ramification of mycorrhizal fungi; in contrast, in saprobic fungi such as Schizophyllum commune, IAA did not induce morphogenetic changes. Mycorrhiza responded by increasing its Hartig net formation. The IAA of fungal origin acts as a diffusible signal, influencing root colonization and increasing Hartig net formation in ectomycorrhiza.
authors.affiliation: Friedrich Schiller University, Institute of Microbiology, Microbial Communication, Jena, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Krause
authors.affiliation: Friedrich Schiller University, Institute of Microbiology, Microbial Communication, Jena, Germany.
authors.forename: Catarina
authors.initials: C
authors.lastname: Henke
authors.affiliation: Friedrich Schiller University, Institute of Microbiology, Microbial Communication, Jena, Germany.
authors.forename: Theodore
authors.initials: T
authors.lastname: Asiimwe
authors.affiliation: Friedrich Schiller University, Institute of Microbiology, Microbial Communication, Jena, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ulbricht
authors.affiliation: Max Planck Institute for Chemical Ecology, Jena, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Klemmer
authors.affiliation: Max Planck Institute for Chemical Ecology, Jena, Germany.
authors.forename: Doreen
authors.initials: D
authors.lastname: Schachtschabel
authors.affiliation: Max Planck Institute for Chemical Ecology, Jena, Germany.
authors.forename: Wilhelm
authors.identifier: http://orcid.org/0000-0001-6784-2534
authors.initials: W
authors.lastname: Boland
authors.affiliation: Friedrich Schiller University, Institute of Microbiology, Microbial Communication, Jena, Germany erika.kothe@uni-jena.de.
authors.forename: Erika
authors.initials: E
authors.lastname: Kothe
mesh_terms: D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D007210:Indoleacetic Acids / Q000378:metabolism*; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development*; D028222:Picea / Q000382:microbiology*; D012567:Schizophyllum / Q000166:cytology / Q000187:drug effects; D017422:Sequence Analysis, DNA; D055439:Tricholoma / Q000235:genetics / Q000378:metabolism*
chemical_list: D004271:DNA, Fungal; D007210:Indoleacetic Acids; C030737:indoleacetic acid