A REGENERATION PROTOCOL FOR SUNFLOWER (HELIANTHUS-ANNUUS L) PROTOPLASTS

Hypocotyl protoplasts of four different Helianthus annuus genotypes we re cultivated for 22 - 28 days in agarose droplets covered with liquid medium. In the first week, supplementation of the medium with plant g rowth regulators was at a 0.8/1 ratio of cytokinin and auxin followed by a high auxin concentration in the second week and a cytokinin to au xin ratio of 8/1 in the third and fourth week. Following transfer onto solid medium containing cytokinin and auxin in a proportion of 40/1 m orphogenic callus started to form globular structures that developed i nto leaf primordia. Subsequent shoot elongation and rooting were obtai ned on hormone free medium after dipping the cut shoots into high auxi n solution. Thirteen weeks after protoplast isolation, plantlets could be transferred to the greenhouse. Shoot regeneration was obtained for all four cultivars (Florom-328, Cerflor, Euroflor, Frankasol) at diff erent rates reflecting their regenerative potential.