PT  - JOURNAL ARTICLE
AU  - Shunsuke Watanabe
AU  - Naoki Takahashi
AU  - Yuri Kanno
AU  - Hiromi Suzuki
AU  - Yuki Aoi
AU  - Noriko Takeda-Kamiya
AU  - Kiminori Toyooka
AU  - Hiroyuki Kasahara
AU  - Ken-Ichiro Hayashi
AU  - Masaaki Umeda
AU  - Mitsunori Seo
TI  - The Arabidopsis NRT1/PTR FAMILY Protein NPF7.3/NRT1.5 is an Indole-3-butyric Acid Transporter Involved in Root Gravitropism
AID  - 10.1101/2020.06.04.131797
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.06.04.131797
4099  - http://biorxiv.org/content/early/2020/06/05/2020.06.04.131797.short
4100  - http://biorxiv.org/content/early/2020/06/05/2020.06.04.131797.full
AB  - Active membrane transport of plant hormones and their related compounds is an essential process that determines the distribution of the compounds within plant tissues and, hence, regulates various physiological events. Here, we report that the Arabidopsis NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY 7.3 (NPF7.3) protein functions as a transporter of indole-3-butyric acid (IBA), a precursor of the major endogenous auxin indole-3-acetic acid (IAA). When expressed in yeast, NPF7.3 mediated cellular IBA uptake. Loss-of-function npf7.3 mutants showed defective root gravitropism with reduced IBA levels and auxin responses. Nevertheless, the phenotype was restored by exogenous application of IAA but not by IBA treatment. NPF7.3 was expressed in pericycle cells and the root tip region including root cap cells of primary roots where the IBA-to-IAA conversion occurs. Our findings indicate that NPF7.3-mediated IBA uptake into specific cells is required for the generation of appropriate auxin gradients within root tissues.Competing Interest StatementThe authors have declared no competing interest.