A calcium sensor-interacting protein kinase negatively regulates salt stress tolerance in rice (Oryza sativa)

Protein kinases are signal transduction factors that play a central role in acclimation. In this study, the function of a calcium sensor-interacting protein kinase, OsCIPK03, was characterised in the salt stress response of rice (Oryza sativa L.). Transgenic plants overexpressing OsCIPK03 exhibited an increased sensitivity to salt stress during both seed germination and seedling growth. By contrast, transgenic RNA interference lines that underexpressed OsCIPK03 were significantly more tolerant to NaCl stress than the wild-type. In response to salt stress, rice that underexpressed OsCIPK03 accumulated more proline than non-transformed plants. Furthermore, several stress-responsive genes were identified as being differentially expressed in the transgenic plants. Together, these results suggest that OsCIPK03 functions as a negative regulator of salt stress tolerance in rice.