Genome Constitution And Phylogenetic Analysis Of High Ploidy Species In Elytrigia

Elytrigia Desvaux is a perennial genus of the tribe Triticeae?Poaceae?.The main morphological characteristics of this genus are strongly rhizimatous,long anther,cross-pollinating and Spikelets 1 per node.In 1810,Desvaux separated Agropyron repens from Agroryron and established a new genus,Elytrigia Desvaux.This genus contain a type species?E.repens?and other species that those species belong to Agropyron have strongly rhizimatous.But this treatment gained a little recognition until a hundred years.The taxonomic status of Elytrigia genus have controversial until now,that this genus was established by Desvaux in 1810,and then treated as a genus,sectional status within Agropyron,subgenus of Agropyron or section of Elymus by different taxonomists,respectively.Tzvelev is the USSR agrostologist responsible for popularizing the concept of Elytrigia as a genus in modern taxonomy.Elytrigia Tzvelev is a genus of about 30 species,which including both rhizomatous and caespitose cross pollinating grasses previously in traditional Agropyron,except the crested wheatgrasses.He separated those species into four sections including section Hyalolepis,section caespitosae,section Elytrigia and section Juncea.In 1978,Melderis deemed that Elytrigia as a genus is unreasonable and absorbed Elytrigia into Elymus where the caespitose species were placed in section Caespitosae and the rhizomatous species went into section Elytrigia in flora of Europaea.Some species of Elytrigia and Elymus have similar morphological characteristics.In 1923,Tzvelev indicated that Elytrigia and Elymus has close relationship and may combine as one genus.He treated those species into two genera based on two reasons.One is conventional,the other is meant to obtain more evidences form morphologic anatomy and biochemistry.In 1984,L?ve divided Triticeae species into 37 genera according to the genomic system of classification which different species with same genome or genome constitution were classified into one genus.Based on this principle,he divided Elytrigia species into other genera including Lophopyrum?E?,Thinopyrum?J?,Pseudoroegneria?St?,Elytrigia?StJE?and Elymus?StH?according genomic constitution.Elytrigia L?ve contain 8 speices and 12 subspeices.Dewey absorbed Lophopyrum into Thinopyrum and deemed that Elytrigia contain five species,Elytrigia repens,E.pungens,E.lolioides,E.pycnantha and E.elongatiformis.The genome formula of Elytrigia is StX?X symbol is unknown?.With the constant-depth study,many studies indicated that genomic constitution of Elytrigia repens?a type species of Elytrigia?is St₁St₁St₂St₂HH.According genome classification system,this species should be transferred into the genus Elymus L..Yen and Yang deemed that the reasonability of Elytrigia is controversial.Genomic constitution of other speicies must be resolve and those species will be absorbed into other genera according genomic constitution.In this study,species marker of St genome,signal copy nuclear gene Acc1,DMC1,multi-copy nuclear gene ITS,chloroplast gene trnL-F and in situ hybridization were used to investigate nuclear genome composition,Maternal donor,genomic constitution and origin.The main results were showed as follows:1.Used degenerated oligonucleotide primer PCR?Dop-PCR?,Dot-blot,and FISH,the FISH marker of St genome were screened.Results from FISH indicated that repeat signal from St genome mainly contain five types:?1?Dispersive signals were present on terminal region of chromosome;?2?Bright dot signals were displayed on terminal region of chromosome;?3?Dispersive signals were present on entire chromosome;?4?Signal were present on centromeric region;?5?Dispersive signals were displayed on entire chromosome and terminal region of some chromosomes have weak signals.Used E?E^e and E^b?as control,11 FISH markers were obtained and those markers have different pattern on St and E chromosome.Signals produced by one marker,named as St₂-80,were present on the entire arm of chromosomes of the St genome,except in the centromeric region.On the contrary,St₂-80 signals were present in the terminal region of chromosomes of the E,H,P,and Y genomes.No signal was detected in the A and B genomes,and only weak signals were detected in the terminal region of chromosomes of the D genome.St₂-80 signals were obvious and stable in chromosomes of different genomes,whether diploid or polyploid.Therefore,St₂-80 is a potential and useful FISH marker that can be used to distinguish the St genome from those of other genomes in Triticeae.2.In order to investigate genomic constitution,nuclear genome composition and origin of Elytrigia lolioides,signal copy nuclear gene Acc1,multi-copy nuclear gene ITS,chloroplast gene trnL-F and in situ hybridization were used.Data from ITS indicated that genomes of E.lolioides most probably been contributed by Pseudoroegneria and Hordeum.Acc1 data indicated that in addition to Pseudorogneria and Hordeum,Lophopyrum was the third potential donor of E.lolioides.Data from cpDNA showed that Pseudoroegneria is maternal donor of E.lolioides.Moreover,data from specific FISH marker for St genome indicated that E.lolioides has two sets of St genomes.Both GISH results and FISH confirmed the presence of Hordeum genome in this species.When E genome was used as the probe,there were no any signals on the forty-two chromosomes.The E-like copy of Acc1 sequences were detected in E.lolioides which might due to introgression from E genome species.Phylogenetic and in-situ hybridization indicated presence of Pseudoroegneria and Hordeum genome in E.lolioides.Two sets of Pseudoroegneria genomes might be differentiated in hexaploid E.lolioides.Genome formula of E.lolioides was designed as St₁St₁St₂St₂HH.Therefore,we suggested this species should be classified into the genus Elymus L.and recorrected as Elymus lolioidus?Kar.er Kir.?Meld..3.Single copy nuclear gene Acc1,DMC1,multi-copy nuclear gene ITS,chloroplast gene trnL-F and in situ hybridization were used to investigate nuclear genome composition and origin of E.pycnantha and E.pungens.Genome of E.pycnantha and E.pungens have most probably been contributed by Pseudoroegneria,Lophopyrum and Agropyron.Data from DMC1 indicated that E.pycnantha and E.pungens have two different E-like copies?E1 and E2?.This suggests that the DMC1 gene may have been duplicated without chromosome doubling,possibly induced by transposable element.Data from cpDNA showed that Pseudoroegneria and Lophopyrum is may maternal donor of E.pycnantha and E.pungens.Species of Agropyron may do not directly participate in speciation of those two species.Combining our results with previous findings,genomic constitutions of E.pycnantha and E.pungens were designed as StStEEPP and St₁St₁St₂St₂EEPP.Therefore,we support the treatment of E.pycnantha and E.pungens from Yen and Yang and those two species be absorbed into Psammopyrumá.L?ve.4.In order to investigate genomic constitution,nuclear genome composition and origin of Elytrigia pontica signal copy nuclear gene Acc1,multi-copy nuclear gene ITS,chloroplast gene trnL-F and in situ hybridization were used.Data from Acc1 and ITS indicated that Lophopyrum is main donor for E.pontica.Pseudoroengeia and Crithopsis may participate in speciation of E.pontica.Results from special marker of St genome indicated that no St genome chromosome were found in E.pontica.Results from two color GISH showed that centromeric and pericentromeric regions of 28 chromosomes have St genome signals.In addition,some chromosomes have banding or dotted signals on arms.Combining with previous studies and our results,genomic constitution was designed as EEEEEEEEEE.Our results indicated extensive chromosomal recombination between St and E genome may occur in speciation of E.pontica.5.Signal copy nuclear gene Acc1,multi-copy nuclear gene ITS,chloroplast gene trnL-F and in situ hybridization were used to investigate nuclear genome composition and origin of E.elongatiformis.Results from GISH and phylogenetic analysis indicated that Genome of E.elongatiformis have most probably been contributed by Pseudoroegneria.Four sets of Pseudoroegneria genomes might be differentiated in octaploid E.elongatiformis.According our results and previous findings,genome formula of E.elongatiformis was designed as St₁St₁St₂St₂St₃St₃St₄St₄.Therefore,we suggested this species should be classified into the genus Pseudoroegneria L?ve and recorrected as Pseudoroegneria elongatiformia?Dorb.?Y.H.Zhou et L.Wang.