Meiotic polyploidization in Darwin hybrid tulips

In our study, 2n gamete producing F1 hybrids of Darwin hybrids (T. gesneriana × T. fosteriana) have been selected and used as pollen donor with the aim of producing of polyploid tulips. In total, 308 one-year-old BC1 seedlings resulting from crosses between diploid and triploid T. gesneriana cultivars and diploid 2n gametes producers have been tested by flow cytometry analysis. Complementary, chromosome number and genome composition was evaluated for selected genotypes through genomic in situ hybridization (GISH) analysis. The progenies from crosses at diploid level (2x × 2x) were mostly diploids, whereas a few seedlings were triploids. In crosses 3x × 2x, 81 genotypes were tetraploids and 25 seedlings were pentaploids. Cytological analyses using GISH of the sexual polyploid progenies have shown considerable amounts of intergenomic recombination in the BC1 generations which is desirable for introgression breeding.