Genomic Constitutions And Systematic Studies On Elymus Villosus Muhl.ex Willd

Elymus villosus Muhl.ex Willd,which was originally reported as a new species named Elymus villosus Muehlen in Enumeratio Plantarum edited by Willdenow,is a perennial tetraploid grass in the tribe Triticeae(Poaceae).It restrictedly distributs in some regions of the United States and Canada.The habitats of this species prefer banks,rock slope of calcium or salt in the forests and shrubs,also in alluvial soil or sand grounds.Morphologically,E.villosus is similar to the species in Elymus.Cytogenetic evidence suggested its tetraploid origin(2n = 4x = 28).However,the pattern of speciation for E.villosus including the genome donor and phylogenetic relationship,are still lacking.In this study,we investigated the genomic constitutions and phylogenetic relationship of E.villosus based on genomic in situ hybridization(GISH)and DNA information to infer the origin of the genome and the genetic relationship among the related species in Triticeae.The main results showed as below:1.In genomic in situ hybridization(GISH)analysis for E.villosus(PI 297899),H genome DNA of Hordeum bogdanii Wilensky servered as probe and St genome DNA of Pseudoroegneria libanotica(Hack.)D.R.Dewey servered as block.It was suggested that 14 chromosomes show pink fluorescence hybridization signals,which indicated that E.villosus contain the H genome from Hordeum.14 chromosomes showed light green fluorescence signals when probing with St genome DNA of Pse.libanotica and blocking with H genome DNA of H.bogdanii.The result indicated that E.villosus contain the St genome from Pseudoroegneria.Based on the above GISH analysis,the genomic constitution of E.villosus was StH.2.The trnL-F sequences were analyzed for 2 E.villosus accessions,together with 30 samples from diploid genera in the tribe Triticeae and 17 allotetraploids in Elymus L.sensu lato.The results showed that:(1)the St genome may serverd as potential maternal donor;(2)the maternal lineages of E.villosus was derived from the Pseudoroegneria species from America.3.Thirty-eight haplotypes of the Accl gene,twenty-three haplotypes of the Pgkl gene and twenty haplotypes of the DMC1 gene were isolated from nineteen plant taxa including E.villosus and other allotetraploid plants in Elymus.Combining these haplotypes sequences with 31-34 gene sequences presenting eighteen basic genomes in Triticeae,phylogenetic analyses were carried out to discuss the genomic constitutions,the genome donor of E.villosus and the phylogenetic relationships between E.villosus and the allotetraploid species with StP,StY,or StEe genomes in Elymus.The results showed that:(1)the genomic constitution of E.villosus is StH;(2)the H genome of E.villosus was originated from American Hordeum;(3)E.villosus was most closely related to North America Elymus species with StH genomes;(4)E.villosus was phylogenetically distinct from the tetraploid species with StP,StY,or StEe genomes.4.Combined morphological evidence with our molecular cytogenetic and phylogenetic analyses,it can be concluded that E.villosus is proved to be an effective species of Elymus.