Occurrence of SDR 2N-gametes in Lilium hybrids

The mechanism of SDR 2n-pollen formation was analyzed in two intra-sectional diploid (2n = 2x = 24) Lilium hybrids (Enchantment x L. pumilum). Variable frequencies of 2n-pollen were found. Meiotic analysis indicated that the intra-sectional hybrids showed perfect chromosome pairing in most cases at metaphase I and normal anaphase I movement of pollen mother cells (PMCs), but produced 2n-pollen by second division restitution (SDR). A high bivalent formation (11.9II and 11.8II, respectively) at metaphase 1, irregular meiotic division such as unbalanced chromosome separation and chromatic fragmentation resulted yet in acceptable pollen fertility for cross-pollination. The hybrids were fertile, and when used as male parents, offspring could tie generated. The significance of the occurrence of 2n-pollen for the breeding of lilies was analyzed.