Selection of diploid tuberous Solanum hybrids for 2n-egg formation using 2x⋅4x-crosses

Abstract

Diploid families of Tuberosum hybrids as well as Tuberosum-wild species F1 hybrids were generated to select 2n-egg producing genotypes of different genetic backgrounds. Plants were selected if they produced more than four seeds per berry after pollination with tetraploid males (2x⋅ot4x-crosses). From the nine families of Tuberosum hybrids that were derived from one or two 2n-egg producing parents, 12 out of 82 (15%) 2n-egg producing plants were selected. From the 32 families of Tuberosum-wild species F1 hybrids, 21 of 274 (8%) 2n-egg producing plants were selected. The level of 2n-egg formation was estimated in 25 selected diploid hybrids and five control clones (three high, one moderate and one low 2n-egg producers) on the basis of seed set following 2x⋅4x-crosses using 13 tetraploid males in four crossing years. Besides the effect of the diploid 2n-egg producing female on the seed set following 2x⋅4x-crosses (P = 0.0001), there was a significant effect of the tetraploid male (P = 0.0001), whereas the effect of the crossing year (P = 0.0688) was less significant. On the basis of differences in the seed set following 2x⋅4x-crosses as compared to the control clones for low, moderate and high level of 2n-egg formation, the level of 2n-egg formation in two of the newly selected hybrids was classified as very high, four were high, sixteen were moderate and three were low. The significance of the selected hybrids for the genetic analysis of various restitution mechanisms of 2n-egg formation is discussed.