Electric Gene Expression in Single-cells of Rice Protoplast via Ca2+ Entering the Cell

Spatial distribution of intracellular Ca2+ concentration was measured with a spectro-imaging system composed of an image slicer (10×10 channels), a grism, and a high sensitive CCD camera. The Ca2+ concentration of each single protoplast was different from others both at a steady state (10–100 nmol dm−3) and after electric stimulation. Therefore traceable observation of each single-cell was essential, which contrasted conventional methods dealing with an average of many cells. When a pulsing electric stimulation was applied to single-cells of rice protoplast, the transient variation of intracellular Ca2+ concentration was observed and chitinase gene expression followed (16 out of 36 cells, 44.4%). Its significance level was estimated as 90% by χ2-test.