Production of unreduced or 2n gametes during meiosis is a common consequence of interspecific hybridization in plants. In the present work, five different bread wheat cultivars were crossed with an accession of Ae. triuncialis and interspecific F1 hybrids (MVT, NAT, OMT, PIT and ZAT) were produced. Meiosis in pollen mother cells (PMCs) of F1 hybrids, pollen viabilities, and seed set ratio were analyzed. Restitution meiosis and consequently unreduced viable pollen were observed. Immunolabeling against phosphorylated histone H3 at serine-10 (phosphoH3S10) suggested that unreduced male gametes were produced by first division restitution (FDR). FDR was more frequent in some hybrids, resulting in higher rates of unreduced male gamete formation and F2 seed set. The F2 embryos were highly variable in chromosome number ranging from 35 to 70 suggesting that unreduced gamete formation led to spontaneous partial and complete amphiploids.
