title: Novel somatic hybrids (Solanum tuberosum L.+Solanum tarnii) and their fertile BC1 progenies express extreme resistance to potato virus Y and late blight.
abstract: Solanum tarnii, a wild diploid, tuber-bearing Mexican species belonging to the series Pinnatisecta is highly resistant to Potato virus Y (PVY) and Colorado potato beetle and shows a strong hypersensitive reaction to Phytophthora infestans. Therefore, it could be a potential source of resistance to pathogens for potato breeders. S. tarnii (2n=2x=24) is reproductively isolated from tetraploid Solanum tuberosum and hence difficult to include in potato breeding programmes. In this study, interspecific somatic hybrids were produced for the first time by protoplast electrofusion of the cells of potato cv. Delikat (Solanum tuberosum L.) and Solanum tarnii. The hybrid nature of the regenerants was confirmed by simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers and by morphological analysis and flow cytometry. Selected somatic hybrids were successfully backcrossed with cv. Delikat. Parental lines, primary somatic hybrids and BC1 progeny were assessed for resistance to PVY by mechanical inoculation, grafting and exposure to viruliferous aphid vectors in the field, and resistance to late blight (P. infestans) by detached leaflet and whole tuber tests. The somatic hybrids showed no symptoms of viral infection and most of them displayed high levels of resistance to foliage blight. The BC1 progenies were highly resistant to PVY and a few were resistant to foliage blight. Selected hybrids and BC1 clones were evaluated in the field for tuber quality and tuber yield. Some BC1 clones produced yields of good quality tubers. The results confirm that both the resistance to PVY and to late blight of S. tarnii is expressed in somatic hybrids, and PVY resistance is transferred to BC1 progeny, whereas blight resistance is harder to transfer. Somatic hybridization again proved to be a valuable tool for producing pre-breeding material with increased genetic diversity.
authors.affiliation: Julius Kuehn Institute, Federal Research Centre for Cultivated Plants, Institute for Breeding Research on Agricultural Crops, Erwin-Baur-Str. 27, 06484, Quedlinburg, Germany. ramona.thieme@jki.bund.de
authors.forename: Ramona
authors.initials: R
authors.lastname: Thieme
authors.forename: Elena
authors.initials: E
authors.lastname: Rakosy-Tican
authors.forename: Tatjana
authors.initials: T
authors.lastname: Gavrilenko
authors.forename: Olga
authors.initials: O
authors.lastname: Antonova
authors.forename: Jörg
authors.initials: J
authors.lastname: Schubert
authors.forename: Marion
authors.initials: M
authors.lastname: Nachtigall
authors.forename: Udo
authors.initials: U
authors.lastname: Heimbach
authors.forename: Thomas
authors.initials: T
authors.lastname: Thieme
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D000818:Animals; D001042:Aphids / Q000502:physiology; D002999:Clone Cells; D005298:Fertility; D006824:Hybridization, Genetic; D007113:Immunity, Innate / Q000235:genetics* / Q000276:immunology; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology* / Q000821:virology*; D011003:Ploidies; D017800:Potyvirus / Q000502:physiology*; D011523:Protoplasts