title: Auxin influx inhibitors 1-NOA, 2-NOA, and CHPAA interfere with membrane dynamics in tobacco cells.
abstract: The phytohormone auxin is transported through the plant body either via vascular pathways or from cell to cell by specialized polar transport machinery. This machinery consists of a balanced system of passive diffusion combined with the activities of auxin influx and efflux carriers. Synthetic auxins that differ in the mechanisms of their transport across the plasma membrane together with polar auxin transport inhibitors have been used in many studies on particular auxin carriers and their role in plant development. However, the exact mechanism of action of auxin efflux and influx inhibitors has not been fully elucidated. In this report, the mechanism of action of the auxin influx inhibitors (1-naphthoxyacetic acid (1-NOA), 2-naphthoxyacetic acid (2-NOA), and 3-chloro-4-hydroxyphenylacetic acid (CHPAA)) is examined by direct measurements of auxin accumulation, cellular phenotypic analysis, as well as by localization studies of Arabidopsis thaliana L. auxin carriers heterologously expressed in Nicotiana tabacum L., cv. Bright Yellow cell suspensions. The mode of action of 1-NOA, 2-NOA, and CHPAA has been shown to be linked with the dynamics of the plasma membrane. The most potent inhibitor, 1-NOA, blocked the activities of both auxin influx and efflux carriers, whereas 2-NOA and CHPAA at the same concentration preferentially inhibited auxin influx. The results suggest that these, previously unknown, activities of putative auxin influx inhibitors regulate overall auxin transport across the plasma membrane depending on the dynamics of particular membrane vesicles.
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, CZ-165 02 Prague 6, Czech Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Lanková
authors.forename: Richard S
authors.initials: RS
authors.lastname: Smith
authors.forename: Bedrich
authors.initials: B
authors.lastname: Pesek
authors.forename: Martin
authors.initials: M
authors.lastname: Kubes
authors.forename: Eva
authors.initials: E
authors.lastname: Zazímalová
authors.forename: Jan
authors.initials: J
authors.lastname: Petrásek
authors.forename: Klára
authors.initials: K
authors.lastname: Hoyerová
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D002477:Cells; D006016:Glycolates / Q000494:pharmacology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D010648:Phenylacetates / Q000494:pharmacology*; D014026:Nicotiana / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D006016:Glycolates; D007210:Indoleacetic Acids; D010648:Phenylacetates; C029718:3-chloro-4-hydroxyphenylacetic acid; C008586:2-naphthoxyacetic acid; C018610:1-naphthoxyacetic acid