Fertility and meiotic mechanisms of hybrids between chromosome autoduplication tetraploid wheats and Aegilops species

During the production of Triticum-Aegilops amphidiploids, it was observed that some F1 hybrids between Triticum ssp. and Aegilops ssp. were self-fertile, with seed set ranging from 0.97 to 39.72%. Seeds from fertile F1's were spontaneous amphidiploids, as determined by root-tip chromosome counts. The present study revealed that the autoduplication of chromosomes in these F1's was caused by the tetraploid wheat parents T. persicum PS5 and T. durum DR147. Detailed meiotic studies of T. persicum PS5 crossed with Ae. squarrosa showed that during meiosis, there were two ways by which unreduced gametes could be formed: first, some of the PMCs omitted the first meiotic division and only underwent the second meiotic division and second, first division restitution with premature cytokinesis, which resulted in an asymmetrical dyad composed of one anucleate cell and one cell with a restitution nucleus. This cell produced two unreduced microspores by a normal second division. The use of this new knowledge has resulte...