SEED PROTEIN VARIATION WITHIN ACCESSIONS OF WILD AND CULTIVATED POTATO SPECIES AND INBRED SOLANUM-CHACOENSE

Soluble proteins in seed potato were analyzed by electrophoresis (PAGE). The Index of Variation (IV) was calculated in order to estimate variation within each accession of wild and cultivated potato species and S. chacoense selfed lines. Seeds of 34 accessions representing 14 species from six taxonomic series were analyzed. The IV of S. chacoense selfed lines decreased from 47.7 in the S2 to 12.9 in the S7 generation. The average IV for the self-incompatible diploid species was 41.2, whereas that of the self-compatible diploid species, S. polyadenium, was 21.3. Tetraploid S. tuberosum ssp. andigena and S. sucrense had an average IV of 62.2, which is much higher than that observed in any other diploid species. The naturally selfing species S. acaule (4x), and its colchicine-doubled derivative (8x), showed very low variation (IV=7.5). The IV appears to reflect heterozygosity and is affected by the breeding mode and the genetic constitution of diploid parents for derived polyploids.