RESISTANCE TO POTATO-VIRUS-Y IN SOMATIC HYBRIDS BETWEEN SOLANUM-ETUBEROSUM AND SOLANUM-TUBEROSUM X S-BERTHAULTII HYBRID

Somatic hybrids between a potato virus Y (PVY) resistant Solanum etube rosum clone and a susceptible diploid potato clone derived from a cros s between S. tuberosum Gp. Tuberosum haploid US-W 730 and S. berthault ii were evaluated for resistance to PVY. All but one of the tested som atic hybrids were significantly more resistant than cultivars 'Atlanti c' and 'Katahdin'. However, none was as resistant as the S. etuberosum parent. One hexaploid somatic hybrid, possibly the product of a tripl e-cell fusion involving one S. etuberosum protoplast and two haploidxS . berthaultii protoplasts, was as susceptible to PVY infection as the cultivars. Tetraploid progeny of the somatic hybrids, obtained from cr osses with Gp. Tuberosum cultivars, were neither as resistant as the m aternal somatic hybrid parent, nor as susceptible as the paternal cult ivar parent. It appears that the introgression of PVY resistance from (1EBN) S. etuberosum into (4EBN) S. tuberosum (EBN-endosperm balance n umber) will be successful through the use of somatic hybridization and subsequent crosses of the somatic hybrids back to S. tuberosum.