Rare instances of haploid inducer DNA in potato dihaploids and ploidy-dependent genome instability

In cultivated tetraploid potato, reduction to diploidy (dihaploidy) allows hybridization to diploid germplasm, introgression breeding, and may facilitate the production of inbreds. Pollination with haploid inducers yields maternal dihaploids, as well as triploid and tetraploid hybrids. It is not known if dihaploids result from parthenogenesis, entailing development of embryos from unfertilized eggs, or genome elimination, entailing missegregation and loss of paternal chromosomes. A sign of genome elimination is the occasional persistence of haploid inducer DNA in some of the dihaploids. We characterized the genomes of 919 putative dihaploids and 134 hybrids produced by pollinating tetraploid clones with three haploid inducers, IVP35, IVP101, and PL4. Whole-chromosome or segmental aneuploidy was observed in 76 dihaploids with karyotypes ranging from 2n=2x-1=23 to 2n=2x+3=27. Of 74 aneuploids with additional chromosomes, 66 contained chromosomes from the non-inducer parent and 8 showed ch...