Identification of somatic hybrids of dihaploid lines and by species specific RAPD patterns and assessment of disease resistance of the hybrids

Symmetric somatic hybrids were produced by electrofusion of protoplasts of two dihaploid tuber-bearing potato ( L.) lines and Phil., a diploid non-tuber-bearing wild potato species. A total of 985 plants was obtained. Verification of nuclear hybridity of putative hybrids was based on additive RAPD patterns, general morphological characteristics and chromosome counts. 53 (90%) calli regenerated into plants which were identified as somatic hybrids. Most of the hybrids were aneuploids at the tetraploid (4×) or hexaploid (6×) level. The 20 hybrids tested expressed a high level of resistance to potato virus Y (PVY) characteristic of the parent. Resistance to late blight ( (Mont.) de Bary) varied between hybrids, but was on average better than that of the fusion parents. Resistance of hybrids to bacterial stem rot ( subsp. (van Hall) Dye) was not superior to that of commercial potato cultivars.