Comparison of FDR-and SDR-derived tetraploid progeny from 2x X 4x crosses using haploids of Solanum tuberosum L. that produce mixed of 2n eggs
1998
Douches, D.S. | Maas, D.L.
The relationship between heterozygosity and heterosis in tetraploid potato (Solanum tuberosum subsp. tuberosum L., 2n = 4x = 48) was examined in a series of first-division restitution (FDR)- and second-division restitution (SDR)-derived tetraploid sub-populations. The subpopulations were constructed using two 2n egg-producing, mixed-mode haploids (2n = 2x = 24) crossed to three tetraploid (2x = 4x = 48) potato clones. Half-tetrad analysis using a codominant electrophoretic marker (Pgm-2), which is closely linked to the centromere, discriminated between FDR- and SDR-derived 4x progeny. The FDR:SDR ratio of the 4x progeny observed was dependent upon the haploid parent used in the 2x x 4x cross. Field studies were conducted between 1992 and 1996 to compare the yield and specific gravity of the two sub-populations and their parents from three crosses. There was no difference in the total tuber yield or specific gravity between the FDR- and SDR-subpopulations based upon family means, despite the expectation that FDR-derived progeny would transmit a greater portion of the genome's heterozygosity intact than SDR-derived progeny. The 4x parent in each family had a higher yield than either 4x progeny subpopulation. Inbreeding, as a consequence of the haploidization process and a lack of genetic diversity, may have negated any advantage of the FDR-derived progenies over the SDR-derived progenies.
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