Abstract
Chromosome constitution was studiod in plants regenerated from cultured hypocotyl tissue of tomato (Lycopersicon esculentum L.). A majority (8.5.3 % ) of the rcgenerants from the apical end of hypocotyl pieces. were diploids. On the other hand, a high level (67.9 %) of pol.vploidy and mixoploidy was found among the regenerants from t, he basal end. The basal end contained, on average, 14 pg of IAA per hypocotyl piece, while no IAA was detected in the apical end. Only dip]oids were regenerated from the basal end on medium supplemented lvith kinetin. These results suggest 1) a high amount of endogenous auxin resulted from the basipetal polar transport plays a role in the induction of polyploidy and 2) kind of exogenous cytokinin affects the frequency of polyploidization in the presence of auxin. Structural aberrations (deletions) were detected in satellito chromosomes Our results suggest the usefulness of hypocotyl tissues for in, vitro production of plants with normal chromosome constitution in tomato.
