The Arabidopsis NRT1/PTR FAMILY protein NPF7.3/NRT1.5 is an indole-3-butyric acid transporter involved in root gravitropism

Abstract

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.

Arabidopsis NPF2.13 functions as a critical transporter of bacterial natural compound tunicamycin in plant–microbe interaction

“…The npf2.13‐2 single mutant still displayed TM sensitivity and TM absorption ability (Figs 2b,c, 5d,e), indicating that NPF2.13‐independent TM import occurs in plants. As the Arabidopsis NPF proteins comprise 53 members, which share similar sequences and functions (Tsay et al ., 2007; Wang et al ., 2018), we examined whether the following NPF proteins function redundantly with NPF2.13 in mediating TM entry into cells: NPF6.3, a nitrate/auxin transporter (Huang et al ., 1996; Guo et al ., 2001; Krouk et al ., 2010); NPF6.4, a putative polyamine transporter (Tong et al ., 2016); NPF7.3, a nitrate/IBA transporter (Lin et al ., 2008; Watanabe et al ., 2020); and NPF2.12, a nitrate/gibberellic acid (GA) transporter (Almagro et al ., 2008; Chiba et al ., 2015; Wulff et al ., 2019). However, the T‐DNA insertional mutants of these NPF genes showed WT‐like TM sensitivity (Fig.…”

Molecular identification and physiological functional analysis of NtNRT1.1B that mediated nitrate long-distance transport and improved plant growth when overexpressed in tobacco

“…The result showed that compared with transformants carrying the empty vector pYNR, yeast cells of △ynt harboring NtNRT1.1B restored the growth on 0.5 mM NO − 3 , comparable to its WT strain, NCYC495 (△leu), transformed with pYNR as a positive control (Figure 1). In addition, as some nitrate and peptide transporters characterized in the NRT1/ PTR family are reported to be proton-coupled permeases for the movement of nitrate, potassium, and/or auxin (Wang et al, 2012;Watanabe et al, 2020), the effect of medium pH on NtNRT1.1Bfacilitated NO − 3 transport in yeast was examined. However, pYNR-NtNRT1.1B-harboring transformants showed no obvious difference in growth rate at pH levels ranging from 5 to 7 (Figure 1), suggesting that the NtNRT1.1B-encoding protein could mediate NO − 3 import from media across the plasma membrane (PM) of yeast cells independent of pH.…”

The MdABI5 transcription factor interacts with the MdNRT1.5/MdNPF7.3 promoter to fine-tune nitrate transport from roots to shoots in apple

“…In plants, K + /NO 3 − absorption, and transport are somehow coordinated and NRT1.5 is capable of transporting nitrate and potassium 6 . In addition, NRT1.5/NPF7.3 is an IBA transporter involved in root gravitropism 18 . Nitrate is both a crucial nutrient and a signaling molecule for plants.…”

“…In addition to K + /NO 3 - , recent research has found that NRT1.5 transports IBA (indole-3-butyric acid) more efficiently than IAA, and IBA is the preferred substrate of NRT1.5 in vivo. NRT1.5-mediated IBA uptake into specific cells is involved in root gravitropism 18 .…”