Overexpression of a C3HC4-type RING E3 ligase gene, OsRFPHC-13, improves salinity resistance in rice, Oryza sativa, by altering the expression of Na+/K+ transporter genes

Salinity stress is a major restriction to increasing crop production. We characterized the Oryza sativa C3HC4-type RING E3 ligase-13 (OsRFPHC-13), which contributes a positive role in enhancing salinity insensitivity. Expression of OsRFPHC-13 was highly induced by treatment with 100 mM NaCl, 20% PEG, or 100 µM ABA. The OsRFPHC-13-GFP fusion protein was expressed in the chloroplasts and cytosol of the rice protoplasts. An in vitro ubiquitination assay confirmed that OsRFPHC-13 possesses E3 ligase activity; however, the mutation of OsRFPHC-13C232A did not show this activity. OsRFPHC-13-overexpressing plants showed a dwarf phenotype, short primary root length, and small lateral root number compared to WT and osrpfhc-13. In contrast, under salt stress, OsRFPHC-13-overexpressing plants showed enhanced salinity insensitivity by reducing the accumulation of Na+ in shoots and roots, increasing the activity of ROS scavenging, and positively regulating the expression of Na+/K+ transporter genes compared to WT and osrpfhc-13. In addition, OsRFPHC-13-overexpressing plants exhibited increased ABA sensitivity in the germination assay but decreased sensitivity in osrpfhc-13 compared to WT. These results suggest that OsRFPH-13 E3 ligase positively regulates the response to salinity via an ABA-dependent mechanism in rice. •OsRFPHC-13, which is induced by salinity, possesses E3 ligase activity.•Overexpression of OsRFPHC-13 contributes to enhanced salinity insensitivity in rice.•OsRFPHC-13 is related to ABA sensitivity and is involved in plants growth.•OsRFPHC-13-overexpressing plants show positive regulation of expressions of Na+/K+ transporter genes in response to salinity.