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AtNPF2.5 Modulates Chloride (Cl−) Efflux from Roots of Arabidopsis thaliana

Bibliography:

Bo Li, Jiaen Qiu, Maheswari Jayakannan, Bo Xu, Yuan Li, Gwenda M. Mayo, Mark Tester, Matthew Gilliham and Stuart J. Roy. AtNPF2.5 Modulates Chloride (Cl−) Efflux from Roots of Arabidopsis thaliana. Frontiers in Plant Science. https://doi.org/10.3389/fpls.2016.02013

Authors:

Bo Li, Jiaen Qiu, Maheswari Jayakannan, Bo Xu, Yuan Li, Gwenda M. Mayo, Mark Tester, Matthew Gilliham and Stuart J. Roy

Keywords:

Arabidopsis thaliana, chloride transport, MIFE, NPF2.5, salinity tolerance, TEVC

Year:

2017

Abstract:

​The accumulation of high concentrations of chloride (Cl−) in leaves can adversely affect plant growth. When comparing different varieties of the same Cl− sensitive plant species those that exclude relatively more Cl− from their shoots tend to perform better under saline conditions; however, the molecular mechanisms involved in maintaining low shoot Cl− remain largely undefined. Recently, it was shown that the NRT1/PTR Family 2.4 protein (NPF2.4) loads Cl− into the root xylem, which affects the accumulation of Cl− in Arabidopsis shoots. Here we characterize NPF2.5, which is the closest homolog to NPF2.4 sharing 83.2% identity at the amino acid level. NPF2.5 is predominantly expressed in root cortical cells and its transcription is induced by salt. Functional character​isation of NPF2.5 via its heterologous expression in yeast (Saccharomyces cerevisiae) and Xenopus laevis oocytes indicated that NPF2.5 is likely to encode a Cl− permeable transporter. Arabidopsis npf2.5 T-DNA knockout mutant plants exhibited a significantly lower Cl− efflux from roots, and a greater Cl− accumulation in shoots compared to salt-treated Col-0 wild-type plants. At the same time, NO−3NO3− content in the shoot remained unaffected. Accumulation of Cl− in the shoot increased following (1) amiRNA-induced knockdown of NPF2.5 transcript abundance in the root, and (2) constitutive over-expression of NPF2.5. We suggest that both these findings are consistent with a role for NPF2.5 in modulating Cl− transport. Based on these results, we propose that NPF2.5 functions as a pathway for Cl− efflux from the root, contributing to exclusion of Cl− from the shoot of Arabidopsis.

ISSN:

1662-5153