Molecular diversity of the 5S nuclear ribosomal DNA inCampeiostachyswithStHYhaplome constitution

Abstract

AbstractTo detect the genomic constitutions and investigate the evolutionary relationships betweenCampeiostachysDrobov andElymusL. species, we have cloned and analyzed 271 5S nuclear ribosomal DNA sequences from 27 accessions of these species, mostly of Chinese origin. We identified LongH1, ShortS1, and LongY1 unit classes in nineCampeiostachysorElymusspecies. The identification of the three orthologous unit classes was confirmed by the neighbor‐joining tree of each unit class from PAUP and the phylogeny tree of three unit classes from MrBayes. The results suggested that theseElymusspecies compriseStYHhaplomes and should be included inCampeiostachys. The phylogeny tree showed a clear separation between theS1 unit class andY1 unit class. However,Y1 unit class sequences formed a sister clade to theS1 unit class, implying that although theStandYhaplomes might have some affinity, they are distinct from one another. The phylogeny tree also indicated that the five species in sect.Turczaninovia(C. dahuricavar.cylindrica,C. dahuricavar.dahurica,C. dahuricavar.tangutorum,E. purpuraristatus, andE. dahuricusTurcz. ex Griseb. var.violeusC. P. Wang & H. L. Yang) might share a more recent common ancestor, whereas the four species in sect.Elymus(C. nutans,E. breviaristatus(Keng) Keng ex Keng f.,E. sinosubmuticus(Keng) Keng f., andE. atratus(Nevski) Hand.‐Mazz.) share a close relationship. By identifying only one type of unit class for each haplome, we propose that the 5S nuclear ribosomal DNA sequences of species withinCampeiostachysmight have undergone haplome‐specific concerted evolution.