OsDSR-1, a calmodulin-like gene, improves drought tolerance through scavenging of reactive oxygen species in rice (Oryza sativa L.)

Abstract

Calmodulin-like (CML) genes regulate plant growth, development, and responses to abiotic stresses such as salinity and drought. Many genes encoding CML proteins have been identified from rice (Oryza sativa), but their functions remain largely unknown. Our characterization of one putative CML gene, OsDSR-1 (O. sativa Drought Stress Response-1), showed that its protein binds Ca2+ and displays Ca2+-dependent conformational changes. In contrast to wild-type (WT) and OsDSR-1-RNA interference (OsDSR-1-Ri) plants, transgenic rice plants that overexpress OsDSR-1 were significantly more drought tolerant and had increased sensitivity to abscisic acid. Furthermore, their concentrations of free proline and soluble sugars and the activities of reactive oxygen species-scavenging enzymes as well as the transcript levels of many ROS-scavenging and stress-related genes were significantly enhanced under drought stress. Much less hydrogen peroxide and malondialdehyde accumulated in OsDSR-1-overexpressing (OsDSR-1-OE) plants than in either the Ri or WT plants. All of these results suggest that OsDSR-1 plays important roles in conferring tolerance to drought in rice by decreasing the occurrence of oxidative damage.