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

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 Ca 2+ and displays Ca 2+ -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.