Abstract
N-1-naphthylphthalamic (NPA) causes the abnormal growth and development of plants by suppressing polar auxin transport. The mechanisms underlying this inhibition, however, have remained elusive. In our current study in Arabidopsis, we show that a defect in the auxin transporter P-glycoprotein 19 (PGP19) suppresses the inhibitory effects of NPA on hypocotyl phototropism and gravitropism, but not on hypocotyl elongation. Expression analysis using the auxin reporter gene DR5:GUS further suggests that NPA inhibits the asymmetric distribution of auxin in a PGP19-dependent manner. These data indicate that PGP19 plays an important role in the mechanism of auxin lateral translocation inhibition by NPA. In addition, we introduce recent studies on the phenotype of pin3pgp19 mutant in this meeting.
