New insights into the evolutionary history of Bromus pumilio and Bromus gracillimus based on nuclear and plastome molecular data

Bromus L., classified in its own tribe Bromeae, is a large and complicated grass genus containing about ۱۶۵annual to perennial species that is widely distributed in temperate regions of the world. To reassess thephylogenetic relationships among B. pumilio and B. gracillimus, species whose respectively classificationwithin Bromus sects. Boissiera and Nevskiella, and other sections of the Bromus genus, the phylogeneticanalyses of ۴۶ Bromus accessions and ۴ outgroup specimens were conducted based on DNA sequences fromfour molecular markers (nrDNA ITS and ETS and plastid rpl۳۲-trnLUAG and matK) in this study. Sequenceswere assembled, trimmed, and visually assessed using Geneious ۱۱.۱.۵ software and edited sequences foreach gene were aligned separately using the MAFFT v۷.۳۸۸ alignment algorithm. Then, sequences wereconcatenated as two combined nuclear and plastid DNA dataset matrices using SequenceMatrix.Phylogenetic relationships of Bromus sections were eventually reconstructed by using maximum parsimony,Maximum Likelihood, and Bayesian analyses. In the phylogenetic trees derived from both nrDNA and plastidsequences, Bromus s.l. is monophyletic with strong support and B. pumilio and B. gracillimus are maximallysupported as sister taxa. The relationship of the B. pumilio–B. gracillimus lineage to other Bromus lineagesdiffers between the plastid and nrDNA trees. In the nrDNA trees, B. densus and B. pumilio–B. gracillimusare sister groups, whereas in the plastid trees B. pumilio–B. gracillimus and B. sect. Ceratochloa form astrongly supported clade, and this clade and B. densus are successive sister groups to the rest of the genus.

کلیدواژه ها:

Bromus sect. Boissiera ، Bromus sect. Nevskiella ، grasses ، molecular phylogenetics ، evolutionary reconstruction