CYTOGENETIC RELATIONSHIPS BETWEEN THE DIPLOID OAT A. PROSTRATA AND THE TETRAPLOIDS A. BARBATA, A. MAGNA AND A. MURPHYI

Abstract

The diploid oat Avena prostrata and the tetraploid A. barbata share the same general morphological characteristics which are also found in the diploid A. strigosa. Chromosome pairing and fertility of the triploid hybrids involving A. barbata and the two diploids suggest that A. prostrata is not as related to A. barbata as A. strigosa and most probably did not participate in the formation of this tetraploid. This conclusion is also supported by the number of the satellited chromosomes in the three oat species and their hybrids and by chromosome pairing in the hybrid involving A. strigosa × A. prostrata amphidiploid and A. barbata. It is speculated that the tetraploid A. barbata had evolved from A. strigosa and another yet undiscovered strigosa-like diploid oat. Some cytological attributes of this hypothetical diploid are suggested. Morphologically and cytologically A. prostrata is unrelated to the tetraploids A. magna and A. murphyi.