HIGH-FREQUENCY OF TETRAPLOIDY IN AGROBACTERIUM-MEDIATED TRANSFORMANTSREGENERATED FROM TUBER DISKS OF DIPLOID POTATO LINES

Variations in the ploidy level of 69 transgenic potato (Solanum tubero sum L.) plants regenerated from the tuber discs of 17 diploid lines we re studied: 24 plants (35%) were diploid, the other 45 plants (65%) we re tetraploid. Seventy-eight control regenerants obtained without Agro bacterium inoculation showed a relatively low tendency to tetraploidiz ation (35%). The results obtained suggested that chromosome doubling o ccurred frequently in diploid potato lines during the tissue culture p rocess for regeneration. Putative somaclonal changes in in vitro-forme d tuber proteins were detected in three out of six transformants by el ectrophoretic analysis.