Taxonomy Of Some Species And Taxonomic Status Of Genus Campeiostachys(Poaceae:Triticeae)

Elymus L.sensu lato included seven basic genomes,and the species with the same genome or genome combinations were classified into one genus.Therefore,Elymus s.l.was further divided into ten genera,including Elymus s.s.,Roegneria,Douglasdeweya,Kengyilia,Campeiostachys,Anthosachne,Pascopyrum,etc.Of which,Campeiostachys is a perennial allohexaploid taxon whose genome composition is St,Y,and H.St genome originated from Pseudoroegneria and H genome is from Hordeum.However,the origin of the Y genome remains unknown.There are five genera(Roegneria,Kengyilia,Campeiostachys,Anthosachne,and Connorochloa)in Triticeae with Y genome and no species with HY genome composition.Therefore,Campeiostachys is likely to have originated from a natural cross between the species in the genus Roegneria with the St Y genome and in Hordeum with the H genome.Based on the morphological characteristics,it is challenging to distinguish Campeiostachys species from Elymus s.s.and Roegneria.But they can be easily distinguished from each other using cytological and phylogenetic analyses.With the more profound insight into this field,the genome composition of more species in Triticeae has been identified,making it easier to classify them.However,the genome composition of many polyploid species has not been determined,and the genome composition of some species is controversial.More and more species with St YH genomes have been identified among the dubious taxa of Elymus and Roegneria.How many species are there in Campeiostachys? What are the relationships among the species? The taxonomic status and origin of the genus Campeiostachys are still unclear.In the present study,genome analysis,genomic in situ hybridization,single-copy nuclear genes Acc1 and DMC1,chloroplast sequences mat K and rps16 were used to identify the genome composition of some dubious taxa of Elymus s.l.,revise the taxonomic of some species,and discuss the systematic status,origin and maternal donor of Campeiostachys.The main results are as follows:1.Genomic in situ hybridization and Acc1 and DMC1 sequences were used to identify the genome composition of Elymus atratus.The results showed that:(1)E.atratus is a hexaploid species with 42 chromosomes.Of the 42 chromosomes,14 are the St genome,14 are the Y genome,and 14 are the H genome.(2)Phylogenetic analysis of Acc1 sequences showed that E.atratus contained St,Y,and H genomes copies.(3)Phylogenetic analysis of the DMC1 sequences also showed that E.atratus contained St,Y,and H genomes copies.Therefore,E.atratus is an allohexaploid species with St YH genomes.Based on the genomic classification system in Triticeae,it was classified into Campeiostachys and treated as Campeiostachys atrata(Nevski)Y.H.Zhou,H.Q.Zhang et L.Tan.2.Artificial hybridization,genomic in situ hybridization,and phylogenetic analysis were used to identify the genome composition of Elymus sinosubmuticus and E.breviaristatus,and explore the biosystematics relationships between them.The results showed that:(1)The chromosome pairing of hybrids indicated that E.sinosubmuticus has the same genome composition as E.breviaristatus.(2)Genome in situ hybridization showed that E.sinosubmuticus and E.breviaristatus contained 42 chromosomes,including 28 chromosomes are the St Y genome and 14 chromosomes are the H genome.(3)Phylogenetic analysis based on Acc1 and DMC1 sequences showed that E.sinosubmuticus and E.sinosubmuticus contained St,Y,and H genomes copies.(4)The fertility results showed that E.sinosubmuticus and E.breviaristatus hybrids had higher fertility and no significant reproductive isolation.(5)Comparison of morphological characteristics between E.sinosubmuticus and E.breviaristatus showed similarities,except for significant differences in the length of lemma awn.Therefore,E.sinosubmuticus belongs to the Campeiostachys,and it is reasonable to treat it as a subspecies of E.breviaristatus and treated as Campeiostachys breviaristata(Keng)Y.H.Zhou,H.Q.Zhang et C.R.Yang subsp.sinosubmutica(S.L.Chen)Y.H.Zhou,H.Q.Zhang et L.Tan.3.Phylogenetic analysis based on Acc1 and DMC1 sequences explores the taxonomic status and origin of Campeiostachys and clarifies the genetic relationship of some suspicious species.The results showed that:(1)The genome composition and origin of Campeiostachys differed from that of Roegneria and Elymus,so it should be treated as a separate genus.(2)Phylogenetic analysis of DMC1 sequences showed that the genus Hordeum was the H genome donor of Campeiostachys species and multiple origins of H genome in Campeiostachys species.(3)Combined with morphological characteristics,artificial hybridization,and phylogenetic analysis results of our study,Campeiostachys purpuraristata as a variety of C.dahurica is more reasonable,renamed as Campeiostachys dahurica var.purpuraristata.(4)In combination with morphological characteristics,geographical distribution,artificial hybridization,and phylogenetic analysis results of our study,C.kamoji,C.tsukushiense var.transiens,and C.calcicola may be derived from the same maternal parent and paternal parent,but there is apparent differentiation,so it is reasonable to treat them as separate biological species.(5)The Y genome originated independently.4.mat K and rps16 sequences were used to explore the maternal donor of Campeiostachys.The results showed that:(1)The maternal donor of Campeiostachys was the species with St Y genome.(2)The Campeiostachys species derived their St Y genome from different Roegneria species.In conclusion,it is reasonable to treat Campeiostachys as an independent genus.The species in Campeiostachys were formed by natural hybridization with the species with St Y genome as the maternal parent and the species with H genome as the paternal parent.At present,there are 14 species,15 varieties,and one subspecies in the genus Campeiostachys.