Molecular Cytogenetic Studies On Tetraploid Species In Pseudoroegneria

Pseudoroegneria is erected by (?)skell L(?)ve in 1980 based on genome analysis. Thegenome symbol of Pseudoroegneria species is designated St. The Pseudoroegneria grassesare caespitose, long-anthered, and cross-pollinating perennials. Pseudoroegneria consistsof about 15～20 species that distribute in the Middle East, Transcaucasia, Central Asia,Northern China or Westem North America. Pseudoroegneria is one of the most importantgenome donor genera in tribe Triticeae. The St genome is found in combination with othergenomes in many alloploids genera. Therefore, Pseudoroegneria is important inphylogenetic evolution of tribe Triticeae.Based on the results of genome analysis, some taxa are moved into or grouped out thePseudoroegneria since it was established, and some taxa require further treatment in thefuture. It is still in controversy in taxa treatment of partial species in Pseudoroegneria andrelated genera, especially in some tetraploid species. The phylogenetic relationships arestill obscure among them. The disputes are (1) Roegneria alashanica, R. elytrigioides, R.magnicaespes and R. grandis, which belong to the awnless group in Roegneria, are mostlikely the Pseudoroegneria species distributed in China, (2) Phylogenetic relationshipsamong Pseudoroegneria geniculata ssp. scythica, Elytrigia caespitosa, Et. caespitosa ssp.nodosa and Et. intermedia, which contain E~eSt genomes, need further investigation.Phylogenetic relationships of P. geniculata, P. geniculata ssp. scythica and P. geniculatassp. pruinifera are obscure, (3) The species with PSt genomes have been grouped intoDouglasdeweya from Pseudoroegneria, however, the phylogenetic relationships amongspecies in the two genera and the maternal donor of species in Douglasdeweya are stillunclear, (4) the St genome is differentiated in some degree in Pseudoroegneria and relatedgenera.In the present study, the disputes mentioned above were investigated via the C-banding,GISH, genome analysis, ITS sequences and trnL-F sequences. The purpose is to (1)investigate the phylogenetic relationships among Roegneria awnless species and Pseudoroegneria species, (2) research the phylogenetic relationships among species inPseudoroegneria, (3) study the phylogenetic relationships among Pseudoroegneria,Elytrigia and Douglasdeweya, (4) reveal the differentiation of St genome inPseudoroegneria. The results are as follows:1. The C-banding of 11 Pseudoroegneria taxa were analyzed together with those of fiveRoegneria species, two Elytrigia taxa and two Douglasdeweya species. The resultsindicated that: (1) all diploid species (St) and tetraploid species (StSt) in Pseudoroegneriahad large telomeric bands, the telomeric bands were larger in diploid Pseudoroegneriaspecies; (2) P. geniculata ssp. scythica, Et. caespitosa and Et. caespitosa ssp. nodosa hadsimilarity in their band karyotypes, however, there were great variations among them. P.geniculata ssp. pruinifera had more interstitial and centromeric bands; (3) R. elytrigioideshad distinct telomeric bands, which were similar to those of diploid Pseudoroegneriaspecies. R. alashanica and R. magnicaespes had little and small telomeric bands, smallcentromeric bands, and more and small interstitial bands. The band karyotypes of R.grandis and R. ciliaris were similar, however, R. grandis had larger telomeric bands; (4)There were variations between band karyotypes of D. wangii and D. deweyi, the twospecies were likely to be separated.2. The genomic constitutions of R. alashanica, R. elytrigioides, R. magnieaespes, R.grandis, P. geniculata, P. geniculata ssp. scythica and P. geniculata ssp. pruinifera weredetected with GISH. P. spicata (St), P. libanotica (St), P. stipifolia (St), R. ciliaris (StY), A.cristatum (P), Lo. elongatum (E~e) and Lo. bessarabicum (E~b) were used as probes, and P.strigosa (St), ssDNA and Lo. elongatum (E~e) were used as blocking, respectively. Theresults indicated that: (1) R. alashanica contained one set of St genome, the other set ofgenome was still unknown, however it was not E, P or Y genomes; (2) R. magnicaespescontained one set of St genome, the other set of genome was still unknown, however it wasnot Y genome; (3) R. elytrigioides contained two sets of St genomes; (4) R. grandis and P.geniculata contained one set of St genome respectively, the other set of genome wasclosely related to St genome; (5) the genomic constitutions of P. geniculata ssp. scythicaand P. geniculata ssp. pruinifera were EEStSt and EEEEStSt, respectively.3. The artificial hybrids were obtained with R. alashanica(St-), R. elytrigioides (StSt), R. magnicaespes (St-), R. grandis (STY), P. geniculata (StSt), P. geniculata ssp. scythica(E~eSt), P. geniculata ssp. pruinifera (---), P. cognata (St), P. libanotica (St), P. spicata(St),P. strigosa (StSt), P. tauri (St), R. grandis (StY), Elymus wawawaiensis (HSt),Anthosachne scabra var. scabra (StWY) or Hystrix patula (HSt) as parents respectively.11 combinations were studied with genome analysis. The pollen fertility and seed set wereinvestigated. The results indicated that: (1) R. alashanica contained one set of St genome,the other set of genome was not H; (2) R. grandis contained one set of St genome, the Ygenome in R. grandis was closely related to St genome; (3) the St genome wasdifferentiated in some degree among species used in the present study.4. The ITS sequences of 17 Pseudoroegneria accessions (St or StSt) were analyzedtogether with those of seven Roegneria species (StY or StSt), four Elytrigia accessions(E~eSt or E~bE~eSt), four Lophopyrum accessions (E~b, E~e or E~bE~eE~xStSt), threeDouglasdeweya accessions (PSt), five Agropyron accessions (P), two Australopyrumaccessions (W), two Hordeum accessions (H) and two Psathyrostachys species (Ns). Thestrict consensus tree was obtained with parsimonious analysis. The results indicated that: (1)the St genomes in diploid species were differentiated, the polyploid Pseudoroegneriaspecies were closely related to diploid Pseudoroegneria species; (2) R. alashanica, R.elytrigioides, R. magnicaespes and P. geniculata were closely related; (3) StY genomeswere closely related to St genome, St genome and Y genome might have the same origin;(4) it is unreasonable to treat P. geniculata ssp. scythica and P. geniculata ssp. pruiniferaas the subspecies of P. geniculata, P. geniculata ssp. scythica, P. geniculata ssp. pruinifera,Et. caespitosa, Et. caespitosa ssp. nodosa, Et. intermedia, Et. intermedia ssp. intermediaand Lo. ponticum should be grouped into Trichopyrum; (5) E~b, E~e and St genomes wereclosely related; (6) diploid Agropyron species were the donor of P genome in D. wangiiand D. deweyi, it is reasonable to group them into Douglasdeweya.5. The trnL-F sequences of 16 Pseudoroegneria accessions (St or StSt) were analyzedtogether with those of seven Roegneria species (StY or StSt), three Elytrigia accessions(E~eSt or E~bE~eSt), four Lophopyrum accessions (E~b, E~e or E~eE~e), three Douglasdeweyaaccessions (PSt), four Agropyron accessions (P), one Australopyrum accessions (W), twoHordeum accessions (H) and two Psathyrostachys species (Ns). The strict consensus tree was obtained with parsimonious analysis. The results indicated that: (1) species inPseudoroegneria, Roegneria, Elytrigia, Lophopyrum and Douglasdeweya were clusteredinto one clade, their sequences were homologous and they were closely related; (2)thematernal donor of the polyploid species with St genome were diploid Pseudoroegneriaspecies; (3) diploid Pseudoroegneria species was the maternal donor of D. wangii and D.deweyi, and paternal donor was from diploid Agropyron species; (4) species in Agropyronand Australopyrum were clustered into one clade, their sequences were homologous andthey were closely related.