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Functional Plant Biology Functional Plant Biology Society
Plant function and evolutionary biology
RESEARCH ARTICLE

Overexpression of AtNHX1 increases leaf potassium content by improving enrichment capacity in tobacco (Nicotiana tabacum) roots

Yong Liu A # , Qian Hou B # , Kunle Dong C , Yi Chen D , Zhihong Wang D , Shengdong Xie D , Shengjiang Wu D , Xiaoquan Zhang A * , Shizhou Yu D * and Zhixiao Yang https://orcid.org/0000-0003-0353-094X D *
+ Author Affiliations
- Author Affiliations

A College of Tobacco Science, Henan Agricultural University, Zhengzhou 45002, China.

B Pingliang Agricultural Technology Extension Station, Pingliang 744000, China.

C Luoyang City Company, Henan Provincial Tobacco Company, Luoyang 471000, China.

D Guizhou Academy of Tobacco Science, Guiyang 550081, China.


# These authors contributed equally to this work

Handling Editor: Honghong Wu

Functional Plant Biology 51, FP24144 https://doi.org/10.1071/FP24144
Submitted: 20 May 2024  Accepted: 17 October 2024  Published: 7 November 2024

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing

Abstract

The NHX1 gene encodes a Na+/H+ antiporter located in the tonoplast membrane, which plays critical role in regulating plant salt tolerance. It is also involved in the uptake and accumulation of K in plants; however, its precise mechanism is unknown. In this research, we elucidated the physiological basis underlying the increases in K content induced by NHX1. We evaluated main agronomic traits, leaf K content, K+ uptake kinetics, and root morphological and physiological characteristics from field-planted and hydroponic plants. We included a wild-type tobacco (Nicotiana tabacum) variety (K326) and three transgenic tobacco lines (NK7, NK9, NK10) that overexpress AtNHX1 from Arabidopsis thaliana. Results demonstrated that the agronomic performance of the AtNHX1-overexpressing tobacco lines was similar to K326 in field and hydroponic settings. The three AtNHX1-overexpressing tobacco lines had significantly higher leaf K contents than K326. Under hydroponic condition, enhanced K uptake capacity and a larger maximum K uptake rate were seen in AtNHX1-overexpressing tobacco lines. AtNHX1-overexpressing lines also exhibited significantly superior root morphological and physiological traits relative to K326, including root biomass, root volume, absorption area, root activity, cation exchange capacity, soluble protein content, and H+-ATPase activity. Overexpression of AtNHX1 in tobacco significantly improves the K uptake and accumulation. Therefore, leaf K content greatly increased in these transgenic lines in the end. Our findings strongly suggest that AtNHX1 overexpression increased leaf K content by boosting the capacity of enriching K in tobacco roots, thereby advancing the understanding of the function of AtNHX1.

Keywords: agronomic performance, AtNHX1 gene, kinetics parameters of K+ uptake, overexpression, potassium, root, tobacco, Vmax.

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