Fig. 2.

pis1 mutant carries mutation in the ABCG37 gene for ATP-binding cassette transporter. (A) The G to A substitution in pis1-1 affects ABCG37 splicing, resulting in a 9-aa deletion in the first ATP-binding AAA domain. (B) ABCG37 is expressed in the lateral root cap and epidermis, and shows outer polar plasma membrane localization (immunostaining of a primary root tip with anti-ABCG37). (Inset) Absence of the signal in the pis1-1 mutant. (C) pis1-1 fails to complement the pdr9-2 mutant allele of ABCG37 (seedlings germinated on 200 nM NPA; note the oversensitivity to NPA manifested by reduced root elongation, lateral root formation, and gravitropism).