Cytogenetic relationships between Avena insularis (2n=28) and both A-strigosa (2n=14) and A-murphyi (2n=28)

The newly discovered tetraploid oat Avena insularis was crossed with the diploid A. strigosa and the tetraploid A. murphyi. Considerably reduced chromosome association at meiosis and a low average number of chiasmata per cell of the A. strigosa x A. insularis hybrids indicated that the diploid A. strigosa did not participate in the creation of A. insularis. From A. murphyi, A. insularis differed by four chromosomal rearrangements and the hybrids between them were sterile. The tetraploids A. magna, A. murphyi and A. insularis share the two to four floret large diaspore, which is adapted to heavy alluvial soil. They all, however, diverge from one another by four chromosomal rearrangements. At this point it is not possible to determine whether they have diverged from a single tetraploid progenitor, or developed from different diploid species.