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Zhang, Yanyan, Yifeng Wang, Jemma L. Taylor et al. (2015) "Aequorin-based luminescence imaging reveals
differential calcium signalling responses to salt and reactive oxygen species in rice roots." Journal of experimental botany 66 (9):2535-45

Abstract - It is well established that both salt and reactive oxygen species (ROS) stresses are able to increase the concentration of cytosolic free Ca2+ ([Ca2+]i), which is caused by the flux of calcium (Ca2+). However, the differences between these two processes are largely unknown. Here, we introduced recombinant aequorin into rice (Oryza sativa) and examined the change in [Ca2+]i in response to salt and ROS stresses. The transgenic rice harbouring aequorin showed strong luminescence in roots when treated with exogenous Ca2+. Considering the histological differences in roots between rice and Arabidopsis, we reappraised the discharging solution, and suggested that the percentage of ethanol should be 25%. Different concentrations of NaCl induced immediate [Ca2+]i spikes with the same durations and phases. In contrast, H2O2 induced delayed [Ca2+]i spikes with different peaks according to the concentrations of H2O2. According to the Ca2+ inhibitor research, we also showed that the sources of Ca2+ induced by NaCl and H2O2 are different. Furthermore, we evaluated the contribution of [Ca2+]i responses in the NaCl- and H2O2-induced gene expressions respectively, and present a Ca2+- and H2O2-mediated molecular signalling model for the initial response to NaCl in rice.