Ploidy and morphological characteristics of Solanum tuberosum x Solanum phureja hybrids

In attempt to induce doubled haploids in potato we studied interspecific hybrids between tetraploid Solanum tuberosum cultivars Igor, Jana, Vesna, Romano, Arinda, Fianna, Donald and Vital and Solanum phureja (clone IVP 48). Four out of eight cultivars produced 21 berries in total and 149 seedlings were obtained. Their ploidy was measured using flow cytometry. Analysis revealed 137 tetraploids, 10 triploids and 2 haploids. One haploid, 6 triploids and most of the tetraploids produced tubers. Nine out of 10 triploids were produced in a cross between cv. Igor and S. phureja. The vigour of the haploid plant was weak and produced characteristic long light yellow tubers. Triploid plants were characterized by a dark violet coloration of the stem, which was the same as the coloration of the S. phureja. Tubers had violet skin colour of various intensities and deep eyes. The majority of the tetraploid plants (135) were phenotypically similar to the S. tuberosum, while two plants had a similar violet stem and tubers as the triploids. Triploids were interspecific hybrids and tetraploids were produced by spontaneous chromosome doubling from S. tuberosum gametes. Two tetraploid plants expressing violet coloration might have been interspecific hybrids formed from 2n S. phureja gametes. Further studies are needed to confirm these assumptions.