Characterization The Cytogenetic Relationships And Intraspecific Genetic Diversity Of Five Diploid Species Of Pseudoroegneria Based On Repeat Sequence FISH Karyotype

The genus Pseudoroegneria(Nevski)L?ve(Triticeae,Poaceae)with its genome abbreviated‘St’ accounts for more than 60% of perennial Triticeae species.Although the single-copy gene FISH has identified the homologous chromosomes of the St genome,it is necessary to simplify the probes for the intraspecific non-homologous chromosome identification and distinguish the inter-specific homologous groups.At the same time,there is no cytogenetic report on the genetic relationship and intraspecific genetic diversity among Pseudoroegneria.In this study,we generated tandem repeat probes from Pse.Libanotica(Hack.)D.R.Dewey,identify the cytogenetic karyotype,and compared the inter-and intraspecific karyotype among Pseudoroegneria.The results are as follows:1.We did whole genome sequencing and repeat sequence analysis in Pseudoroegneria libanotica.In total,3 repeat sequence probes(STlib＿96,STlib＿98,and Stlib＿117)were selected.The STlib＿96 and STlib＿117 showed no hybridization signal in common wheat,which may provide the possibility to identify alien St chromosome.2.We established the cytogenetic karyotype of Pse.libanotica using those probs,each homoeologous chromosome can be distinguished.The 5St and 7St displayed different hybridization signals not only within homologous chromosome pairs in single plants but also among different accessions originating from different geography.It indicated that the Pse.libanotica was high heterogeneity which may result from its often-cross pollination system.3.To reveal the genetic relationship within the 5 diploid species of Pseudoroegneria from the perspective of cytogenetics,repeat sequence probes were used to compare their karyotypes.We found that the karyotypes of Pse.libanotica and Pse.tauri were similar,while the non-homologous chromosomes of the other three species could not be distinguished.Therefore,we speculated that Pse.libanotica and Pse.tauri are closely related.At the same time,the karyotypes of Pse.tauri from different geographical sources were compared and analyzed.We found that the hybridization diversity was concentrated in 2St,and 5St.4.The 45 S rDNA and 5S rDNA FISH signals appeared at 1St and 5St in all materials Pseudoroegneria in this study.In addition,additional 5S rDNA sites were found in 1St of two Pse.tauri materials.In summary,three tandem repeats were generated to efficiently identify 1St～7St of Pse.libanotica.The hybridization signal was mainly located in 5St and 7St.The genetic relationship of Pse.libanotica and Pse.tauri are closely related.Our results provide the genetic relationship and diversity of the St genome and offer cytogenetic markers for alien St chromosome identification.