title: Abscisic acid determines arbuscule development and functionality in the tomato arbuscular mycorrhiza.
abstract: The role of abscisic acid (ABA) during the establishment of the arbuscular mycorrhiza (AM) was studied using ABA sitiens tomato (Lycopersicon esculentum) mutants with reduced ABA concentrations. Sitiens plants and wild-type (WT) plants were colonized by Glomus intraradices. Trypan blue and alkaline phosphatase histochemical staining procedures were used to determine both root colonization and fungal efficiency. Exogenous ABA and silver thiosulfate (STS) were applied to establish the role of ABA and putative antagonistic cross-talk between ABA and ethylene during AM formation, respectively. Sitiens plants were less susceptible to the AM fungus than WT plants. Microscopic observations and arbuscule quantification showed differences in arbuscule morphology between WT and sitiens plants. Both ABA and STS increased susceptibility to the AM fungus in WT and sitiens plants. Fungal alkaline phosphate activity in sitiens mutants was completely restored by ABA application. * The results demonstrate that ABA contributes to the susceptibility of tomato to infection by AM fungi, and that it seems to play an important role in the development of the complete arbuscule and its functionality. Ethylene perception is crucial to AM regulation, and the impairment of mycorrhiza development in ABA-deficient plants is at least partly attributable to ethylene.
authors.affiliation: Department of Soil Microbiology and Symbiosis Systems, Estación Experimental del Zaidín, CSIC, Calle Profesor Albareda nº1, 18008 Granada, Spain.
authors.forename: María José
authors.initials: MJ
authors.lastname: Herrera-Medina
authors.affiliation: Institut für Pflanzenschutz, Department für Angewandte Pflanzenwissenschaften und Pflanzenbiotechnologie, Universität für Bodenkultur Wien, Peter-Jordan-Str. 82, A-1190 Wien, Austria.
authors.forename: Siegrid
authors.initials: S
authors.lastname: Steinkellner
authors.affiliation: Institut für Pflanzenschutz, Department für Angewandte Pflanzenwissenschaften und Pflanzenbiotechnologie, Universität für Bodenkultur Wien, Peter-Jordan-Str. 82, A-1190 Wien, Austria.
authors.forename: Horst
authors.initials: H
authors.lastname: Vierheilig
authors.affiliation: Department of Soil Microbiology and Symbiosis Systems, Estación Experimental del Zaidín, CSIC, Calle Profesor Albareda nº1, 18008 Granada, Spain.
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Ocampo Bote
authors.affiliation: Department of Soil Microbiology and Symbiosis Systems, Estación Experimental del Zaidín, CSIC, Calle Profesor Albareda nº1, 18008 Granada, Spain.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: García Garrido
mesh_terms: D000040:Abscisic Acid / Q000235:genetics / Q000502:physiology*; D005030:Ethylenes / Q000378:metabolism; D005658:Fungi / Q000502:physiology*; D018551:Solanum lycopersicum / Q000235:genetics / Q000382:microbiology* / Q000502:physiology*; D009154:Mutation; D038821:Mycorrhizae / Q000502:physiology*
chemical_list: D005030:Ethylenes; D000040:Abscisic Acid; C036216:ethylene