The electroporation pulse is generated by discharging a capacitor across the electrodes in a specially designed electroporation chamber.Either a high voltage (1.5 kV) rectangular wave pulse of short duration or a low voltage (350V) pulse of long duration is used.

The latter can be generated by a home made machine. Protoplasts in an ionic solution containing the vector DNA, are suspended between the electrodes, electroporated and then plated as usual.Transformed colonies are selected as described earlier.

Using electroporation method, successful transfer of genes was achieved with the protoplasts of tobacco, petunia, maize, rice, wheat and sorghum. In most of these cases cat gene associated with a suitable promoter sequence was transferred.

Transformation frequencies can be further improved by

(i) using field strength of 1.25kV/cm,

(ii) adding PEG after adding DNA,

(iii) heat shocking protoplasts at 45°C for 5 minutes before adding DNA and

(iv) by using linear instead of circular DNA.