*Article OsLPR5* **Encoding Ferroxidase Positively Regulates the Tolerance to Salt Stress in Rice**

**Juan Zhao 1,† , Xin Meng 1,†, Zhaonian Zhang <sup>1</sup> , Mei Wang <sup>2</sup> , Fanhao Nie <sup>1</sup> and Qingpo Liu 1,\***

	- Institute of Horticulture, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China

2

† These authors contributed equally to this work.

**Abstract:** Salinity is a major abiotic stress that harms rice growth and productivity. Low phosphate roots (LPRs) play a central role in Pi deficiency-mediated inhibition of primary root growth and have ferroxidase activity. However, the function of LPRs in salt stress response and tolerance in plants remains largely unknown. Here, we reported that the *OsLPR5* was induced by NaCl stress and positively regulates the tolerance to salt stress in rice. Under NaCl stress, overexpression of *OsLPR5* led to increased ferroxidase activity, more green leaves, higher levels of chlorophyll and lower MDA contents compared with the WT. In addition, OsLPR5 could promote the accumulation of cell osmotic adjustment substances and promote ROS-scavenging enzyme activities. Conversely, the mutant *lpr5* had a lower ferroxidase activity and suffered severe damage under salt stress. Moreover, knock out of *OsLPR5* caused excessive Na<sup>+</sup> levels and Na+/K<sup>+</sup> ratios. Taken together, our results exemplify a new molecular link between ferroxidase and salt stress tolerance in rice.

**Keywords:** rice; salinity; *OsLPR5*; ferroxidase; stress

**Citation:** Zhao, J.; Meng, X.; Zhang, Z.; Wang, M.; Nie, F.; Liu, Q. *OsLPR5* Encoding Ferroxidase Positively Regulates the Tolerance to Salt Stress in Rice. *Int. J. Mol. Sci.* **2023**, *24*, 8115. https://doi.org/10.3390/ ijms24098115

Academic Editor: Daniela Trono

Received: 17 March 2023 Revised: 14 April 2023 Accepted: 26 April 2023 Published: 30 April 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
