Identification and characterization of satellite DNAs in Poa L.

Background: Poa L. is a large genus of grass in Gramineae, among which P. pratensis is widely cultivated as turf and forage. Satellite DNA is the main components of the plant genome. Information of satellites will helpful for dissection the genome composition and definition of the phylogeny relationship of these species. However, the knowledge about the satellites in genus Poa is still limited.

Results: Four satellite DNAs were identified using the Repeat Explorer pipeline in HiSeq Illumina reads from diploid plants in P. malaca (2n = 26). Two satellites showed high similarity with the previously identified PpTr-1 and PpTr-3, whereas two others are newly identified with the monomer of 326 bp (Poa-326) and 353 bp (Poa-353) respectively. The clone DNAs of PpTr-1 and PpTr-3, and oligonucleotides designed representing satellites Poa-326 and Poa-353 were probed to test on chromosomes across 13 Poa speceis with different polyploidy level by fluorescent in situ hybridization (FISH). PpTr-1, PpTr-3, and Poa-362 were stably positioned in the subtelomeric regions in nearly all species with the variation of hybridization sites number. However, Poa-353 showed different FISH patterns of multiple regions with the variation of hybridization intensity and distribution sites across species. In addition, 5S rDNA and 45S rDNA were used to characterize the genome of the Poa species. Four rDNA FISH patterns were revealed in the tested species.

Conclusion: Four identified satellite were high conservable across Poa species. Genome distribution of these satellites can be characterized by FISH. The variation of satellite DNAs and rDNA chromosomal distributions between species provide useful information for phylogenetic analysis in genus Poa.