Yang, Da-ping.2009-04-172009-04-1719681968Source: Dissertation Abstracts International, Volume: 68-06, Section: B, page: 3577.http://hdl.handle.net/10393/10898http://dx.doi.org/10.20381/ruor-8510Microspectrophotometric measurements of nuclear DNA of various species of oats revealed substantial differences among the diploid species. The karyotypes had been divided into two distinct groups, A and C, on the basis of cytogenetic studies, and this was confirmed by the microspectrophotometric data. The tetraploid Avena barbata, with the genome AABB, has a lower DNA content than does autotetraploid A. strigosa (AAAA). This suggests that tetraploid oats originated via segmental allotetraploidy rather than via autotetraploidy. The DNA content of the B genome was about 20% lower than that of the A genome. This may serve as a marker in the search for the potential donor of the B genome. Autoradiographic studies of the average durations of mitotic phases in the root tip cells of three oats species with different amounts of nuclear DNA showed that the DNA synthetic phase (S) of diploid and autotetraploid strigosa were similar, suggesting that homologous genomes in Avena species replicate in synchrony. It is proposed that the origin of certain genomes in polyploid oats might be resolved by comparing the replication patterns of chromosomes between the diploid and the polyploid species.110 p.Biology, Molecular.Thesis