Co-Authors:
Shaul-Keinan, O., Agricultural Research Organization (ARO), Volcani Center, Bet Dagan 50 250, Israel
Gadkar, V., Agricultural Research Organization (ARO), Volcani Center, Bet Dagan 50 250, Israel
Ginzberg, I., Agricultural Research Organization (ARO), Volcani Center, Bet Dagan 50 250, Israel
Grünzweig, J.M., Department of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot 76 100, Israel
Chet, I., Department of Plant Pathology and Microbiology, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot 76 100, Israel
Elad, Y., Agricultural Research Organization (ARO), Volcani Center, Bet Dagan 50 250, Israel
Wininger, S., Agricultural Research Organization (ARO), Volcani Center, Bet Dagan 50 250, Israel
Belausov, E., Agricultural Research Organization (ARO), Volcani Center, Bet Dagan 50 250, Israel
Eshed, Y., Agricultural Research Organization (ARO), Volcani Center, Bet Dagan 50 250, Israel
Ben-Tal, Y., Agricultural Research Organization (ARO), Volcani Center, Bet Dagan 50 250, Israel
Kapulnik, Y., Agricultural Research Organization (ARO), Volcani Center, Bet Dagan 50 250, Israel
Abstract:
Phytohormones are known to play a pivotal role in various developmental processes in plants and in arbuscular-mycorrhizal (AM) fungal-host symbiosis. This study focuses on characterizing the changes in the concentrations of auxins, cytokinins and gibberellins in tobacco (Nicotiana tabacum) during the early stages of colonization by Glomus intraradices, using advanced analytical detection techniques. High-pressure liquid chromatography analysis followed by radioimmunoassay detection revealed that AM colonization induced the accumulation of specific zeatin riboside-like and isopentenyl adenosine-like compounds in both roots and shoots. Use of the gas chromatography-mass spectrometry technique on the same developmental stage revealed that gibberellins (GA) of the earl-13-hydroxylation biosynthetic pathway (GA1, GA8, GA19 and GA20) were significantly more abundant in roots, but not shoots, of AM inoculated plants than in those of nonmycorrhizal plants. Indoleacetic acid concentrations (total and free) remained unaltered by AM colonization. This study demonstrates that hormonal changes do occur during AM symbiosis with tobacco, before the fungal benefits manifest.