Production of male fertile interspecific hybrides between cultivated potatoes and valuable for breeding allotetraploid species Solanum stoloniferum

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The germplasm of valuable for breeding wild allotetraploid potato species Solanum stoloniferumis rarely used because of pre- and postzygotic reproductive barriers with cultivated potatoes. One of the factors that complicate crosses between S. stoloniferum and S. tuberosumis unilateral incompatibility (UI).Here, we present the results of application of original SvSv-lines for overcoming UI in crosses with S. stoloniferum and of generating male fertile hybrids derived from this species. SvSv-lines are F2 S. tuberosum dihaploid× S. verrucosum that are male fertile and have D/γ-type cytoplasm. Since they are hybrids on homozygous for Svgene from S. verrucosum, they do not form SvSv-lines and have the same ability for elimination of prezygotic incompatibility as this species.As a result of pollination seven SvSv-lines were pollinated by 26 accessions of S. stoloniferum and a lot of hybrid seeds have been produced.In spite of low percentage of germination (1.9 %), formed 40 seedlings of interspecific hybrids. The experiment on hybridization between SvSv-lines and S. stoloniferum has been reproduced with the accession PI205522 of the wild species, which had DNA markers of PVY and LB resistance genes and “sterile” type cytoplasm W/γ: 950 hybrid seeds and 12 viable seedlings were produced. The genome of the seedlings was doubled by colchicine treatment, which generated hexaploids (F1) that formed highly fertile pollen and set seeds from self-pollination. We were able to cross them as females with the variety Katahdin. Produced pentaploid hybrids (BC1) were readily backcrossed by potato variety Quarta. Seedlings of BC2 were then backcrossed by potato varieties as female and, some of them, as male parents. The substantial part of F1, BC1 and BC2 plants of interspecific hybrids were male fertile (produced a lot functionally fertile pollen).