Action of auxin on cell elongation.
The early time course (0-30 min) of the action of auxin (3-indoleacetic acid) on the elongation of segments from corn coleptiles was studied, using a high-resolution continuous recording technique. Two different effects of auxin were observed: (1) After addition of low auxin concentrations (2 x 10(-7)M) to 4-mm sections, a very rapid (2-3 min) enhancement of elongation was found. Similar early responses were seen following the addition of low concentrations of the methyl ester of indoleacetic acid. (2) Following a large step-up in the auxin level (10(-5), 10(-4), or 10(-3)M), a rapid transient decrease was observed one to three minutes after the addition of indoleacetic acid. It lasted 10-15 minutes at which time the steady rate of auxin-promoted elongation became evident. Similar kinetic patterns of auxin effects other than on elongation and the implications of the findings on hypotheses of the primary action of auxin are discussed.
D007210:Indoleacetic Acids / Q000494:pharmacology*; D007700:Kinetics; D010937:Plant Growth Regulators / Q000494:pharmacology*; D012639:Seeds; D013268:Stimulation, Chemical; D003313:Zea mays / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*
D007210:Indoleacetic Acids; D010937:Plant Growth Regulators