Molecular phylogeny revealed distinct origin of the Y and St genome in Elymus longearistatus (Triticeae: Poaceae)

Abstract

Cytogenetic data has indicated the presence of St and Y genome in Elymus longearistatus (Boiss.) Tzvelev. However, a random amplified polymorphic DNA (RAPD) based sequence tagged site (STS) study suggested one accession of Pseudoroegneria spicata (Pursh) Á Löve (St genome) as a potential Y genome donor candidate in tetraploid E. longearistatus. To examine the origin of Y genome in and the phylogeny of tetraploid E. longearistatus, sequences of cpDNA (RPS16 and TrnD/T intergenic spacer) and single copy nuclear genes (EF-G and HTL) from eight accessions of E. longearistatus, six StY genomic Elymus species and 62 accessions of diploid in Triticeae were analyzed. The cpDNA data suggested that P. stipifolia (St) is the most likely maternal donor of these six Iranian accessions of E. longearistatus, although P. strigosa could not be excluded. Two nuclear gene data convincingly showed that tetraploid E. longearistatus contains two distinct genomes, St and Y genome. The phylogenetic analyses from both the EF-G and HTL rejected the previous suggestion that accession PI232134 of Pseudoroegneria spicata (Pursh) Á Löve (St genome) was potential Y genome donor to E. longearistatus. Phylogenetic analyses revealed a separation of the Y genome sequences in Iranian accessions of E. longearistatus from the sequences in the Pakistan accession, indicating that geographic isolation might influence the evolution of the Y genome in E. longearistatus.