engleski

Comparative analysis of satellite sequences in allotriploid Allium x cornutum and its three parental species

An established minor garden crop, triploid onion Allium  cornutum (2n=3x=24) is traditionally cultivated in coastal Croatia and is used as spice and condiment. Similar triploid onions are cultivated as garden crops in southeastern Asia, Europe and other parts of the world. Our previous molecular, phylogenetic and cytogenetic studies provided evidence for its unique triparental origin with three putative parental species, A. cepa, A. pskemense, and A. roylei. Here we performed de novo identi cation and quanti cation of repetitive DNA families of A. x cornutum and its three parental Allium species by application of next generation sequencing and using the RepeatExplorer pipeline (Novak et al., 2013). The genome coverage of three species was about 0.4X. Nuclear repetitive DNA constituted 53, 05% of A. roylei genome, 57, 18% of A. cepa, 58, 59% of A. pskemense. We identi ed 6 satellite DNA families in A. cepa, 5 in A. pskemense and 4 in A. pskemense. By using PCR, cloning, sequencing and FISH we identi ed three satellite sequences in both diploid progenitors and A. x cornutum. One satellite sequence is similar to well-known terminal satellite sequence in Allium cepa and we mapped it on almost all chromosome ends. The second satellite sequence shows homology to Allium stulosum centromeric sequence and it localizes to the centromeres of several but not all chromosomes. The third satellite sequence is hitherto unknown and it localizes to the terminal and some intercalary positions of several chromosomes of three diploid species and allotriploid. The obtained results in combination with previous data on rDNA phylogeny and mapping will be useful in better understanding of poliploidization and evolutionary history of allotriploid

Allium, alopoliploidy, next-generation sequencing, satellite DNA, FISH

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