title: Ethylene-dependent/ethylene-independent ABA regulation of tomato plants colonized by arbuscular mycorrhiza fungi.
abstract: We investigated the relationship between ABA and ethylene regulating the formation of the arbuscular mycorrhiza (AM) symbiosis in tomato (Solanum lycopersicum) plants and tried to define the specific roles played by each of these phytohormones in the mycorrhization process. We analysed the impact of ABA biosynthesis inhibition on mycorrhization by Glomus intraradices in transgenic tomato plants with an altered ethylene pathway. We also studied the effects on mycorrhization in sitiens plants treated with the aminoethoxyvinyl glycine hydrochloride (AVG) ethylene biosynthesis inhibitor and supplemented with ABA. In addition, the expression of plant and fungal genes involved in the mycorrhization process was studied. ABA biosynthesis inhibition qualitatively altered the parameters of mycorrhization in accordance with the plant's ethylene perception and ethylene biosynthesis abilities. Inhibition of ABA biosynthesis in wild-type plants negatively affected all the mycorrhization parameters studied, while tomato mutants impaired in ethylene synthesis only showed a reduced arbuscular abundance in mycorrhizal roots. Inhibition of ethylene synthesis in ABA-deficient sitiens plants increased the intensity of mycorrhiza development, while ABA application rescued arbuscule abundance in the root's mycorrhizal zones. The results of our study show an antagonistic interaction between ABA and ethylene, and different roles of each of the two hormones during AM formation. This suggests that a dual ethylene-dependent/ethylene-independent mechanism is involved in ABA regulation of AM formation.
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), CSIC, Calle Profesor Albareda no1, 18008 Granada, Spain.
authors.forename: José Ángel
authors.initials: JÁ
authors.lastname: Martín-Rodríguez
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), CSIC, Calle Profesor Albareda no1, 18008 Granada, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: León-Morcillo
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), CSIC, Calle Profesor Albareda no1, 18008 Granada, Spain.
authors.forename: Horst
authors.initials: H
authors.lastname: Vierheilig
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), CSIC, Calle Profesor Albareda no1, 18008 Granada, Spain.
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Ocampo
authors.affiliation: Institut für Botanik, Technische Universität Dresden, Zellescher Weg 20b, 01062 Dresden, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Ludwig-Müller
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), CSIC, Calle Profesor Albareda no1, 18008 Granada, Spain.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: García-Garrido
mesh_terms: D000040:Abscisic Acid / Q000096:biosynthesis / Q000494:pharmacology*; D015169:Colony Count, Microbial; D005030:Ethylenes / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D055137:Glomeromycota / Q000187:drug effects / Q000502:physiology*; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D018551:Solanum lycopersicum / Q000187:drug effects* / Q000235:genetics / Q000382:microbiology*; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D038821:Mycorrhizae / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017973:Tungsten Compounds / Q000494:pharmacology
chemical_list: D005030:Ethylenes; D010940:Plant Proteins; D017973:Tungsten Compounds; C025399:sodium tungstate(VI); D000040:Abscisic Acid; C036216:ethylene; C088137:aminoethoxyvinylglycine; D005998:Glycine