Overexpression of Rice C3HC4-Type RING Finger Protein Gene, OsSIRHC-2, Improves Salinity Tolerance Through Low Na<SUP>+</SUP> Accumulation

초록

Soil salinity negatively affects plant growth, productivity, and metabolism. Rice is known to have more sensitive phenotypes than other cereal crops such as wheat (Triticum aestivum), sorghum (Sorghum bicolor), and barley (Hordeum vulgare). We characterized the molecular function of rice (Oryza sativa) C3HC4 as a really interesting new gene (RING). O. sativa RING finger protein HC-2 (OsSIRHC-2) was highly expressed in 100 mM NaCl and was targeted to the cytosol. An in vitro ubiquitin assay demonstrated that OsSIRHC-2 possessed E3-ubiquitin ligase activity. Under salinity conditions, OsSIRHC-2-overexpressing plants exhibited higher chlorophyll, proline, and soluble sugar contents and lower H2O2 accumulation than wild-type plants, supporting transgenic plants with enhanced salinity tolerance phenotypes. OsSIRHC-2-overexpressing plants exhibited low Na+ accumulation and Na+/K+ ratios in their roots. Low expression of some Na+ transporter genes, especially OsHKT1;4 was consistent with the low Na+ accumulation in transgenic plants. These results suggest that OsSIRHC-2 may play a positive regulatory role in high salinity through the low absorption of Na+. Understanding the salt tolerance mechanisms of OsSIRHC-2 may provide a crucial strategy for plant adaptation to salinity.

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