Differential effects of 1-naphthaleneacetic acid, indole-3-acetic acid and 2,4-dichlorophenoxyacetic acid on the gravitropic response of roots in an auxin-resistant mutant of arabidopsis, aux1.

The agravitropic nature of root growth of an auxin-resistant mutant of Arabidopsis, aux1, was restored when the synthetic auxin 1-naphthaleneacetic acid (NAA) was added to the growth medium; aux1 roots were not resistant to NAA. Neither indole-3-acetic acid nor, 2,4-dichlorophenoxyacetic acid had the same effects as NAA. These differential effects of the three auxins on aux1 defects suggest that AUX1 may encode the auxin influx carrier according to the model proposed by Delbarre et al.