title: Effects of brassinosteroid, auxin, and cytokinin on ethylene production in Arabidopsis thaliana plants.
abstract: Inflorescence stalks produced the highest amount of ethylene in response to IAA as compared with other plant parts tested. Leaf age had an effect on IAA-induced ethylene with the youngest leaves showing the greatest stimulation. The highest amount of IAA-induced ethylene was produced in the root or inflorescence tip with regions below this producing less. Inflorescence stalks treated with IAA, 2,4-D, or NAA over a range of concentrations exhibited an increase in ethylene production starting at 1 microM with increasingly greater responses up to 100 microM, followed by a plateau at 500 microM and a significant decline at 1000 microM. Both 2,4-D and NAA elicited a greater response than IAA at all concentrations tested in inflorescence stalks. Inflorescence leaves treated with IAA, 2,4-D, or NAA exhibited the same trend as inflorescence stalks. However, they produced significantly less ethylene. Inflorescence stalks and leaves treated with 100 microM IAA exhibited a dramatic increase in ethylene production 2 h following treatment initiation. Inflorescence stalks showed a further increase 4 h following treatment initiation and no further increase at 6 h. However, there was a slight decline between 6 h and 24 h. Inflorescence leaves exhibited similar rates of IAA-induced ethylene between 2 h and 24 h. Light and high temperature caused a decrease in IAA-induced ethylene in both inflorescence stalks and leaves. Three auxin-insensitive mutants were evaluated for their inflorescence's responsiveness to IAA. aux2 did not produce ethylene in response to 100 microM IAA, while axr1-3 and axr1-12 showed reduced levels of IAA-induced ethylene as compared with Columbia wild type. Inflorescences treated with brassinolide alone had no effect on ethylene production. However, when brassinolide was used in combination with IAA there was a dramatic increase in ethylene production above the induction promoted by IAA alone.
authors.affiliation: Department of Horticulture, The Pennsylvania State University, University Park, PA 16802, USA. rna@psu.edu
authors.forename: Richard N
authors.initials: RN
authors.lastname: Arteca
authors.forename: Jeannette M
authors.initials: JM
authors.lastname: Arteca
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D060406:Brassinosteroids; D002777:Cholestanols / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism*; D005030:Ethylenes / Q000096:biosynthesis*; D007210:Indoleacetic Acids / Q000378:metabolism*; D013260:Steroids, Heterocyclic / Q000378:metabolism*
chemical_list: D060406:Brassinosteroids; D002777:Cholestanols; D003583:Cytokinins; D005030:Ethylenes; D007210:Indoleacetic Acids; D013260:Steroids, Heterocyclic; C036216:ethylene; C023623:brassinolide