PLANTLET REGENERATION FROM ELECTROSTIMULATED PROTOPLASTS OF SUNFLOWER(HELIANTHUS-ANNUUS L)

Hypocotyl protoplasts from Helianthus annuus L. were electrically stim ulated using different parameters and subsequently cultivated in agaro se droplets with weekly changes of the liquid media. Macroscopic visib le calli (0.1-0.3 mm) were transferred onto solid media supplemented w ith different concentrations of NAA, BAP, and GA3. Colonies reaching a size of about 3 mm were isolated and further cultivated under the sam e conditions. Several calli originating from electrically stimulated p rotoplasts and especially those cultured on relative high auxin concen trations, generated somatic embryos which were characterized by a gree n globular shoot tip and a developing root. Later on differentiation o f the shoot tip occurred on kinetin-containing MS medium leading to pl antlets with stunted shoot axis. No somatic embryos were initiated in control experiments with non-stimulated protoplasts.