Alteration of the genomic composition of Solanum nigrum (+) potato backcross derivatives by somatic hybridization: selection of fusion hybrids by DNA measurements and GISH

Abstract

Fusion experiments were performed with a first (BC1‐6738) and a second (BC2‐9017) generation backcross hybrid of 6x Solarium nigrum (+) 2x potato somatic hybrids with potato cultivars. Because no progeny was obtained from the BC2 genotypes, alternative approaches were sought to overcome the sexual crossing barrier. Five potato genotypes, one of which contains the hygromycin resistance gene, were used in the fusion experiments. All vigorous regenerants were used for the estimation of nuclear DNA content using flow cytometry. Plants with a DNA content higher than that of the BC1‐6738 or BC2 genotypes were considered potential somatic hybrids. Forty‐nine potential somatic hybrids resulted from fusion experiments with BC1‐6738, from which 20 grew vigorously in the greenhouse and flowered. After pollination with several 4x potato cultivars, eight genotypes produced seeded berries and five genotypes gave seedless berries. In addition, 11 of these 13 somatic hybrids were selected for genomic in situ hybridization (GISH) analysis to determine their genomic composition. Nine had exactly or approximately the expected number of 36 S. nigrum and 60 potato chromosomes. In one genotype, only 22 instead of 36 S. nigrum chromosomes were found and one potato chromosome was possibly missing. Only five potential somatic hybrids were detected among the 79 regenerants from BC2‐9017 (+) 2x potato fusion experiments that were analysed by flow cytometry. Two of these hybrids were rather vigorous and did flower, but pollinations with potato have not yet set any berries.

Electrofusion of protoplasts from Solanum tuberosum, S. bulbocastanum and S. pinnatisectum

“…Bintje). These results fully correspond with conclusions made by Horsman et al (2001): it is possible to use FC to distinguish between regenerants of parental genotypes, self-fusion genotypes and desired fusion hybrids. Somatic hybrids can be further confirmed by the analysis of molecular markers such as isozymes (Ling and Iwamassa 1994;Thieme et al 1997), rDNA restriction endonuclease digestion patterns (Miranda et al 1997), RFLP analysis (Oberwalder et al 2000) and RAPD-PCR Mourão Filho et al 1996;Thieme et al 1997).…”

Molecular and morphological characterization of somatic hybrids between Solanum tuberosum L. and S. etuberosum Lindl.

“…In our experiment, somatic hybrids C-13 (?) S. etuberosum were confirmed on the different criteria, as in earlier reports, such as RAPD (Rokka et al 1994;Thieme et al 1997;Naess et al 2001;Barone et al 2002;Szczerbakowa et al 2003;Greplova et al 2008), SSR (Nouri-Ellouza et al 2006;Gillen and Novy 2007; (Thieme et al 1997;Maciejewska et al 1999;Oberwalder et al 2000;Horsman et al 2001;Szczerbakowa et al 2003;Greplova et al 2008), and phenotypic assessment (Novy and Helgeson 1994a;Thieme et al 2008;Szczerbakowa et al 2003;Greplova et al 2008). Confirmation of somatic hybrids was revealed by species-specific diagnostic bands (RAPD and SSR) from both the parental components.…”

Early characterization of somatic hybrids from symmetric protoplast electrofusion of Solanum pinnatisectum Dun. and Solanum tuberosum L.

“…Borgato et al (2007) found only tetraploids in S. marginatum (2n = 2x = 24). However, wide variability in ploidy level and the morphology of somatic hybrids from any given fusion combination proved more common (Shi et al 2006;Szczerbakowa et al 2003b;Horsman et al 2001;Szczerbakowa et al 2001). The tetraploids produced in this study probably arose from the asymmetric fusion pnt 8166 ?…”