The jasmonate-responsive GTR1 transporter is required for gibberellin-mediated stamen development in Arabidopsis

Abstract

Plant hormones are transported across cell membranes during various physiological events. Recent identification of abscisic acid and strigolactone transporters suggests that transport of various plant hormones across membranes does not occur by simple diffusion but requires transporter proteins that are strictly regulated during development. Here, we report that a major glucosinolate transporter, GTR1/NPF2.10, is multifunctional and may be involved in hormone transport in Arabidopsis thaliana . When heterologously expressed in oocytes, GTR1 transports jasmonoyl-isoleucine and gibberellin in addition to glucosinolates. gtr1 mutants are severely impaired in filament elongation and anther dehiscence resulting in reduced fertility, but these phenotypes can be rescued by gibberellin treatment. These results suggest that GTR1 may be a multifunctional transporter for the structurally distinct compounds glucosinolates, jasmonoyl-isoleucine and gibberellin, and may positively regulate stamen development by mediating gibberellin supply.

NRT1.5/NPF7.3 Functions as a Proton-Coupled H+/K+ Antiporter for K+ Loading into the Xylem in Arabidopsis

“…Some members already identified in plants are H + /substrate symporters that utilize the inwardly direct proton gradient (Dm H + ) across the cell membrane and drive the uptake of the substrates (Krouk et al, 2010;Nour-Eldin et al, 2012;Léran et al, 2014;Saito et al, 2015;Tal et al, 2016). However, this study reveals that NRT1.5 functions as a protoncoupled H + /K + antiporter, and external acidic pH promotes K + release out of cells (Figures 7 and 8).…”

“…Arabidopsis and rice (Oryza sativa) contain 53 and 80 NRT1/PTR members, respectively (Tsay et al, 2007), which implies that these proteins have diverse functions in plants, not necessarily limited to nitrate and peptide transport. Most of the identified members in plants are nitrate transporters, but some transport different substrates, for example, indole-3-acetic acid, abscisic acid, gibberellic acid, jasmonoyl-isoleucine, glucosinolates, or amino acids (Krouk et al, 2010;Nour-Eldin et al, 2012;Léran et al, 2014;Saito et al, 2015;Tal et al, 2016). In this study, we identified K + as a novel substrate of NRT1/PTR transporters.…”

“…In Arabidopsis, the NRT1/PTR family contains as many as 53 members, which implies that this family has diverse functions (Tsay et al, 2007). Some members of this family have been shown to participate in the transport of diverse substrates in plants, including nitrate, peptides, glucosinolate defense compounds, and plant hormones (Krouk et al, 2010;Nour-Eldin et al, 2012;Léran et al, 2014;Saito et al, 2015;Tal et al, 2016). Members of the NRT1/PTR family are thought to transport numerous unidentified substrates and have multiple unknown functions (Tsay et al, 2007;Léran et al, 2014).…”

TEMPRANILLO Reveals the Mesophyll as Crucial for Epidermal Trichome Formation

“…Recent studies suggest that GA movement and distribution might be regulated by a group of GA transporters (Chiba et al, 2015;Saito et al, 2015). The NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY (NPF) is a family of proteins initially identified as nitrate or peptide transporters (Tsay et al, 2007;Léran et al, 2014), and was later found to also transport hormones such as auxin and abcisic acid (Krouk et al, 2010;Kanno et al, 2012).…”

Long-distance transport of endogenous gibberellins in Arabidopsis

“…9 Recently, biochemical studies in heterologous systems allowed the identification of several GA transporters, belonging to the NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY (NPF). [15][16][17] The NPFs represent a large family of membrane proteins which transport a wide array of compounds including nitrate, peptides, glucosinolates and phytohormones. 18 Although not demonstrated, it is tempting to speculate that these multifunctional transporters may contribute in the translocation of GA 12 from parenchyma cells to the vessels.…”