INVITRO SHOOT REGENERATION AND CHROMOSOME DOUBLING IN 2X-POTATO AND 3X-POTATO CLONES

The possibility of scaling ploidy levels up and down offers several advantages for genetic studies and breeding work in potato. Shoot regeneration and chromosome doubling in plants regenerated from in vitro cultures were investigated in 4 diploid (2n = 2x = 24) and 2 triploid (2n = 3x = 36) clones. Internode and leaf explants were taken from plants propagated either in vitro as shoot cultures, or in vivo in a greenhouse. Two regeneration procedures were compared. Regeneration frequencies were significantly higher using a two-step regeneration protocol and from leaf explants, while doubling was more efficient starting from in vivo grown plants. No doubling was observed in triploid clones. Considering altogether the percentage of regeneration and doubling, and the number of shoots regenerated per explant, the most efficient conditions were considered leaf explants taken from in vivo grown plants, and cultured according to a two-step regeneration protocol.