Regulation of Root Growth by Auxin-Ethylene Interaction

Abstract

A large portion of indoleacetic acid (IAA)-induced inhibition of excised root tips and virtually all such inhibition of intact roots are the result of IAA-dependent ethylene production. Under certain conditions an additional effect of IAA accounts for a small portion of the inhibition of excised root tips. Ethylene production in response to applied IAA is governed by the level of applied auxin found inside the root. Evidence is presented to confirm the participation of ethylene in the geotropic response of roots.