Agrobacterium tumefaciens-mediated transformation of potato and analysis of genomic instability by RAPD

In order to enhance the system of potato transformation and further regeneration, four potato cultivars were transformed using the Agrobacterium tumefaciens harboring â-glucuronidase (GUS) gene.The results revealed that the highest percentages of shoot formation obtained were for Spunta cv. Stem explants resulted in more callus and regeneration after transformation and selection than leaf explants. In all cases the performance was genotype-dependent. The GUS positive expression ranged from 40 % (Hermes) to 92.8 % (Lady Rosetta) for leaf explants and from 33.3 % (Hermes) to 91.6 % (Lady Rosetta) for stem explants. RAPD analysis elucidated the induction of somaclonal variations, which were also found to be genotype-dependent. It occurs more frequently when new plants are formed via leaf explants, while, using stem as explants were genetically stable. Similarity coefficients among the genotypes as well as among the different stages in tissue culture for each cultivar before and after transformation were calculated. Dendrograms were constructed accordingly.