ISOENZYMATIC VARIATION IN POTATO SOMACLONES (SOLANUM-TUBEROSUM L)

Two enzymatic systems, peroxidase (PER EC 1.11.1.7) and esterase (EST EC 3.1.1.1), were analyzed with polyacrylamide gel electrophoresis usi ng leaves and tubers from first vegetative generation plants obtained from the in vitro culture of potato internodes (Solanum tuberosum L.). The electrophoretic patterns varied when compared to the control plan ts. On average 25.6% of the plants had different isoenzymatic patterns in 136 somaclones of the Macaca, 14 of the Santo Amor and six of the Baronesa cultivars; Santo Amor showed the greatest variation (85.7%), followed by Baronesa (33.3%) and Macaca (19.1%). The largest variation was found in the esterase patterns of the Macaca and Baronesa somaclo nes, while the cultivar Santo Amor showed the greatest number of varia nts in the peroxidase analyses. The isoenzymatic variability found in the somaclones of the studied cultivars indicates the efficiency of th e callus culture technique in the induction of somaclonal variation. T he different responses among the somaclones, obtained from each cultiv ar, may be attributed mainly to the genotypic differences which are a consequence of vegetative tissue culture.