engleski

Comparative cytogenomic analysis of tandemly repeated DNA elements in four Allium species from the section Cepa

Allopolyploidy, which involves both polyploidy and inter­species hybridization, contributes to plant evolution and diversification. Most of the known allopolyploids are based on even­ploidy levels with very few odd­ ploidy level taxa persisting in nature. One of such unusual cases is triploid onion, Allium × cornutum (Clementi ex Visiani, 1842), (2n=3x=24), an established minor garden crop, widespread in the northern hemisphere. By using molecular­phylogenetic approach we previously confirmed its unique triparental origin and successfully identified parental species. One of the ancestors was common onion, Allium cepa L., whereas the two other ancestral species were shown to originate from South­Himalayan regions, Allium pskemense B. Fedtsch and Allium roylei Stearn (Puizina et al. 1999, Fredotović et al. 2014). To better understand the genome evolution of allotriploid and its ancestral species, we performed de novo identification of repetitive DNA families by application of Next generation sequencing utilizing low­pass genome sequence data (~ 2%) and using the RepeatExplorer2 and TAREAN pipelines (Novak et al., 2020). The analyses showed that the genomes of all four species have a quite similar compositions, and that they are dominated by LTR­retrotransposons, making up 40­50% of nuclear DNA, with Tekay and Retand from Ty3 lineage and SIRE from Ty1 lineage being the most abundant. In contrast, satellite DNA was represented by only 0.1 ­ 1.6 % of nuclear DNA and ribosomal DNA on average by 0.3%. The results of comparative repeat analysis revealed shared and species specific repeats. By application of fluorescent in situ hybridization we mapped the two ribosomal and the three satellite DNA repeats from each parental species to the chromosomes of both diploid and allotriploid species.The mapped satellite and rDNA repeats provided useful chromosomal markers which allowed the individual identification of the majority of chromosomes within the analyzed karyotypes

repeatome ; repetitive DNA ; satellite DNA ; ribosomal DNA ; Allium

Sažetak poster objavljenje kao supplement u časopisu FEBS Open Bio, Volume 11, Issue S1