SOMATIC HYBRIDS BETWEEN THE CULTIVATED POTATO SOLANUM-TUBEROSUM L ANDTHE 1EBN WILD-SPECIES SOLANUM-PINNATISECTUM DUN - MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION

Interspecific somatic hybrids between the 1EBN-wild species Solanum pi nnatisectum (S. pnt) and four different diploid breeding lines of Sola num tuberosum (S. tbr) were produced by electrofusion. S. pnt exhibits resistance to Phytophthora infestans and Erwinia blackleg. Somatic hy brids were identified by RFLP analysis using the oligonucleotide (GATA )(4) as a probe. In three of four combinations all regenerates obtaine d were somatic hybrids. All 86 somatic hybrids between the breeding li ne H256/1 and S. pnt were analyzed in detail with respect to morpholog ical and molecular characters; 50% of the somatic hybrids showed norma l intermediate leaf morphology. Tubers of somatic hybrid plants grown in the green house as well as in the field were evenly shaped and rema rkably similar to those of the S. tbr breeding line. Analysis of relat ive DNA content by flow cytometry revealed that 75% of the somatic hyb rids were tetraploid, some were hypotetraploid and others polyploid or mixoploid. Slot blot and RFLP analyses were carried out using repetit ive and some single-copy DNA probes. The genome portion of the S. tbr breeding line was determined by slot-blot analysis using the species-s pecific repetitive probe pSA287. Obviously, most somatic hybrids conta in the complete genomes of both fusion partners. In some of the somati c hybrids, a significantly lower intensity of the S. pnt-specific hybr idization signal indicated a certain degree of asymmetry.