Phylogenetic relationships and the maternal donor ofRoegneria(Triticeae: Poaceae) based on three nuclear DNA sequences (ITS,Acc1, andPgk1) and one chloroplast region (trnL-F)

Roegneriais a polyploid perennial genus in the tribe Triticeae. Some species ofRoegneriaare morphologically similar to genusElymusand have been classified inElymus. To investigate the delimitation and phylogenetic relationships ofRoegneria, nuclear (ITS,Acc1, andPgk1) and chloroplast (trnL-trnF) DNA regions were sequenced for 38 allopolyploid species and 32 diploid species of Triticeae. Phylogenetic analyses of nuclear DNA revealed that allRoegneriaspecies were included in the St and Y genome clades, and that the Y genome was closely related to the V and Xp genomes. The chloroplast DNA dataset showed thatRoegneriaspecies were grouped withPseudoroegneriaspecies. ThePseudoroegneriaspecies from the Middle East (P. libanoticaandP. tauri) and Central Asia (P. strigosa) were more closely related toRoegneriaspecies. The results suggested that: (i) the species containing the St and Y genomes should be segregated fromElymusand treated as a distinct genus,Roegneria, based on the genomic constitution; (ii)P. libanotica, P. tauri, and/orP. strigosapotentially served as the maternal donor of the St genome inRoegneria; (iii) The Y genome ofRoegneriaoriginated from a diploid Y genome species, and the V and Xp genomes may have contributed to Y genome formation; (iv) amongRoegneriaspecies of previously uncertain genomic constitution,R. seriotinawas tetraploid and possessed the StY genomes,E. calcicoluswas hexaploid with the StYH genomic constitution and should be classified inCampeiostachys, R. glaucifoliapossessed the StStY genomes, andR. tschimganicahad the genomic constitution St(1)St(2)Y.

Automated summary

By sequencing nuclear and chloroplast DNA regions, the delimitation and phylogenetic relationships of the Roegneria genus were investigated. The results showed that all Roegneria species were included in the St and Y genome clades, and the Y genome was closely related to the V and Xp genomes. Additionally, Roegneria species were grouped with Pseudoroegneria species, particularly those from the Middle East and Central Asia.