Fertility of somatic hybrids Solanum commersonii (2x, 1EBN) (+) S. tuberosum haploid (2x, 2EBN) in intra- and inter-EBN crosses

Abstract Interspecific somatic hybridization has been performed in potato breeding experiments to increase plant resistance against biotic and abiotic stress conditions. We analyzed the mitochondrial and plastid genomes and 45S nuclear ribosomal DNA (45S rDNA) for the cultivated potato (S. tuberosum, St), wild potato (S. commersonii, Sc), and their somatic hybrid (StSc). Complex genome components and structure, such as the hybrid form of 45S rDNA in StSc, unique plastome in Sc, and recombinant mitogenome were identified. However, the mitogenome exhibited dynamic multipartite structures in both species as well as in the somatic hybrid. In St, the mitogenome is 756,058 bp and is composed of five subgenomes ranging from 297,014 to 49,171 bp in St. In Sc, it is 552,103 bp long and is composed of two sub-genomes of 338,427 and 213,676 bp length. StSc has 447,645 bp long mitogenome with two subgenomes of length 398,439 and 49,206 bp. The mitogenome structure exhibited dynamic recombination mediated by tandem repeats; however, it contained highly conserved genes in the three species. Among the 35 protein-coding genes of the StSc mitogenome, 21 were identical for all the three species, and 12 and 2 were unique in Sc and St, respectively. The recombinant mitogenome might be derived from homologous recombination between both species during somatic hybrid development.

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Fertility of somatic hybrids Solanum commersonii (2x, 1EBN) (+) S. tuberosum haploid (2x, 2EBN) in intra- and inter-EBN crosses

Genome ◽

10.1139/g98-082 ◽

1998 ◽

Vol 41 (6) ◽

pp. 776-781 ◽

Cited By ~ 6

Author(s):

D Carputo ◽

P Garreffa ◽

M Mazzei ◽

L Monti ◽

T Cardi

Keyword(s):

Somatic Hybrid ◽

Potato Breeding ◽

Somatic Hybrids ◽

Seed Viability ◽

Solanum Commersonii ◽

Viable Seeds

Solanum commersonii (+) S. tuberosum hybrids with different endosperm balance numbers (EBN) and ploidy were used in various crossing schemes with 4EBN S. tuberosum cultivars and a 3EBN somatic hybrid to test their behavior in intra- and inter-EBN crosses and to derive a BC1 population for potato breeding. The somatic hybrids included 12 tetraploids (2n = 48, 3EBN), 18 hypotetraploids (2n = 43-47, 3EBN), 2 hexaploids (2n = 72, 4 or 5EBN), and 5 hypohexaploids (2n = 63-70, 4 or 5EBN). The results confirmed that in the potato, EBN is more important than actual ploidy in determining the success or failure of crosses. Indeed, crosses between some hypohexaploid hybrids and S. tuberosum cultivars gave the highest number of viable seeds per berry, and seed viability was similar to that of intra-EBN crosses between varieties. Inter-EBN crosses demonstrated that exceptions to the 2:1 maternal-paternal EBN ratio in the hybrid endosperm can sometimes be tolerated. However, an excess in maternal EBN dosage was better tolerated than an excess in paternal EBN.Key words: EBN, ploidy, potato, Solanum commersonii, somatic hybrids.

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