The Loss of Function of the NODULE INCEPTION-Like PROTEIN 7 Enhances Salt Stress Tolerance in Arabidopsis Seedlings

Quang Tri Le; Won Je Lee; Jun Ho Choi; Dinh Thanh Nguyen; Hai An Truong; Sang-A Lee; Suk-Whan Hong; Hojoung Lee

doi:10.3389/fpls.2021.743832

The Loss of Function of the NODULE INCEPTION-Like PROTEIN 7 Enhances Salt Stress Tolerance in Arabidopsis Seedlings

Front Plant Sci. 2022 Jan 24:12:743832. doi: 10.3389/fpls.2021.743832. eCollection 2021.

Authors

Quang Tri Le¹, Won Je Lee¹, Jun Ho Choi¹, Dinh Thanh Nguyen¹, Hai An Truong¹, Sang-A Lee², Suk-Whan Hong³, Hojoung Lee^{1

4}

Affiliations

¹ Department of Plant Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, South Korea.
² Department of Forest Bio Resources, National Institute of Forest Science, Suwon, South Korea.
³ Department of Molecular Biotechnology, College of Agriculture and Life Sciences, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea.
⁴ Institute of Life Science and Natural Resources, Korea University, Seoul, South Korea.

Abstract

Plants acquire nitrogen, an essential macronutrient, from the soil as nitrate. Since nitrogen availability is a major determinant of crop productivity, the soil is amended with nitrogenous fertilizers. Extensive use of irrigation can lead to the accumulation of salt in the soil, which compromises crop productivity. Our characterization of NODULE INCEPTION (NIN)-like PROTEIN 7 (NLP7), a transcription factor regulating the primary response to nitrate, revealed an intersection of salt stress and nitrate metabolism. The growth of loss-of-function mutant nlp7 was tolerant to high salinity that normally reduces the fresh weight and chlorophyll and protein content of wild type (Col-0). On a medium with high salinity, the nlp7 experienced less stress, accumulating less proline, producing less nitric oxide (NO) and reactive oxygen species (ROS), and expressing lower transcript levels of marker genes, such as RD29A and COR47, than Col-0. Nevertheless, more sodium ions were translocated to and accumulated in the shoots of nlp7 than that of Col-0. Since nlp7 also expressed less nitrate reductase (NR) activity, nitrate accumulated to abnormally high levels with or without salinity. We attributed the enhanced salt tolerance of nlp7 to the balanced accumulation of nitrate anions and sodium cations. Our results suggest that nitrate metabolism and signaling might be targeted to improve salt tolerance.

Keywords: Arabidopsis; NLP7; nitrate reductase; nitric oxide; salt stress tolerance.