MODIFICATION OF CULTIVAR-SPECIFIC REGENERATION CAPACITY OF POTATO EXPLANTS BY PHYTOHORMONES AND BY AGROBACTERIUM ONCOGENES

To overcome low, genotype dependent regeneration capacity of some comm ercially important potato cultivars, two alternative treatments of ste m primary explants were employed: modification of the hormonal composi tion of inductive MS medium and insertion of some Agrobacterium oncoge nes. A replacement of 6-BAP with zeatin in the inductive MS medium sti mulated bud/shoot formation in only two of three tested cultivars with naturally low regeneration capacity. GA3 did not affect the bud initi ation phase (i.e. regeneration capacity of cultivars), it only stimula ted shoot development. The insertion of some bacterial oncogenes (in p articular genes 4, rolB, C and 5) enhanced bud/shoot formation, especi ally in the case of low-regenerating cultivars.