Effects of electroporation pulse wave on the incorporation of viral RNA into tobacco protoplasts

The uptake and expression of cucumber mosaic viral (CMV) RNA by tobacco protoplasts was examined using both square wave and exponential wave electroporation pulses. These electropulses, when supplied at sufficient field strength for a critical duration, enabled RNA to be incorporated and expressed in more than 60% of the surviving protoplasts. The results of experiments using these two electroporation wave forms showed significant differences in RNA uptake and expression. The number of viable protoplasts and cells showing expression of RNA was higher over a much broader range of experimental conditions using the square rather than exponential wave generator, even when both machines were optimized for maximal performance. However, at a narrow range of low field strengths the exponential wave pulse generated a higher percentage of transformants than did the square wave pulse. It was shown that after an electroporation pulse from either wave form, there were viable cells which expressed foreign RNA at predictable levels.