Similar patterns of rDNA evolution in synthetic and recently formed natural populations of Tragopogon (Asteraceae) allotetraploids

摘要: Tragopogon mirus and T. miscellus are allotetraploids (2n = 24) that formed repeatedly during the past 80 years in eastern Washington adjacent Idaho (USA) following introduction of diploids dubius, porrifolius, pratensis 12) from Europe. In most natural populations miscellus, there far fewer 35S rRNA genes (rDNA) dubius than other diploid parent (T. porrifolius or pratensis). We studied inheritance parental rDNA loci resynthesized accessions. investigate dynamics directionality these losses, as well contribution gene copy number variation to derived tetraploids. Using Southern blot hybridization fluorescent situ (FISH), we analyzed numbers distribution highly reiterated seven lines synthetic (110 individuals) four (71 individuals). Variation among parents accounted for observed imbalances detected F1 hybrids but cannot explain frequent deviations repeat additivity seen allotetraploid lines. Polyploid lineages involving same differed genotype, indicating conditions immediately genome doubling crucial changes. About 19% individuals had equal contributions parents, 74% were skewed towards either pratensis-type units, only 7% more copies dubius-origin compared two parents. Similar genotype frequencies populations. Despite directional reduction locus is maintained 82% all allotetraploids. Uniparental reductions homeologous occurred both allopolyploids. The extent changes was generally higher hypothesize locus-specific chromosomal early generations allopolyploids may influence patterns evolution later generations.