Phylogenetic Analysis Of Kengyilia And Its Affinitive Genera (Poaceae: Triticeae) Based On The Sequences Of Acc-1 And Pgk-1 Genes

Kengyilia Yen et J.L.Yang,Agropyron Gaertn.,Roegneria C.Koch,Pseudoroegneria (Nevski) A.L(o|¨)ve and Douglasdeweya C.Yen,J.L.Yang et B.R.Baum are important perennial genera in the tribe Triticeae(Poaceae).Many species are fine herbages.Some species have characters of resistance to diseases,insect resistance and stress tolerance,which make them precious germplasm resources in crop breeding. However,definitions of the five genera and their precise taxonomic ranks have been under discussion.To estimate the phylogenetic relationships of the five genera and the relationships of the genomes or genome combinations included in these genera,the sequences of Acc-1 gene and Pgk-1 gene of 5 species in Kengyilia(StYP),2 species in Douglasdeweya(StYP),4 tetraploids in Roegneria(StYP),2 diploids in Agropyron (StYP) and 4 diploids in Pseudoroegneria(StYP) were analysed and phylogenetic trees based on the two genes were constructed.The main results are as follows:1.The different sequences of Acc-1 and Pgk-1 of Kengyilia,Roegneria and Douglasdeweya were clustered with the sequences of Pseudoroegneria and Agropyron respectively,forming St clade and P clade,which indicated that Kengyilia,Roegneria and Douglasdeweya had close relationships with Pseudoroegneria and Agropyron.The results also supported that the St genome of Kengyilia,Roegneria and Douglasdeweya originated from Pseudoroegneria,and the P genome from Agropyron.2.In both St clade and P clade of Acc-1 trees and Pgk-1 trees,Kengyilia species were clustered directly with Roegneria species,showing a close relationship between Roegneria and Kengyilia.However,Douglasdeweya species were not clustered directly with the Kengyilia species,from which we can conclude that Douglasdeweya species probably did not take part in the speciation of Kengyilia species.3.In both phylogenetic trees constructed by the sequences of Ace-1 gene and Pgk-1 gene,four Pseudoroegneria species(Pse.libanotica,Pse.strigosa,Pse.stipifolia,Pse. tauri) did not form a monophyletic group,which indicated that phylogenetic differentiation existed in Pseudoroegneria species.Thus,they had polyphyletic origins and different Pseudoroegneria species might have taken part in the formation of polyploid species in Pseudoroegneria,Kengyilia and Douglasdeweya.4.In the dendrogram obtained from the sequences of Acc-1 gene,St genorne was clustered with P genome after it was clustered with Y genome,which indicated that the relationship between St genome and Y genome was closer than that between St genome and P genome.5.In the phylogenetic trees constructed by the sequences of Acc-1 gene and Pgk-1 gene,K.batalinii,K.alatavica and K.gobicola that came from central Asia had close affinities and they were not clustered with K.melanthera and K.rigidula that came from Qinghai-Tibet Plateau,which indicated that there were great genetic differentiation between Kengyilia species from central Asia and those from Qinghai-Tibet Plateau.6.In the P clade of the two phylogenetic trees,Kengyilia species from central Asia and those from Qinghai-Tibet Plateau were clustered with Agropyron species from central Asia and those from Qinghai-Tibet Plateau,respectively.Such differentiation were not observed in St genome and P genome,which indicated that the geographical differentiation of Kengyilia was probably caused by the geographical differentiation of Agropyron,and different diploids in Agropyron maybe have taken part in the speciation of different species in Kengyilia.7.The phylogenetic relationships between Kengyilia,Agropyron,Roegneria, Pseudoroegneria and Douglasdeweya were discussed according to the phylogenetic trees constructed from Acc-1 gene and Pgk-1 gene.The results were consistent with those received from morphology and cytogenetics,which indicated that Acc-1 gene and Pgk-1 gene are useful tools to study the phylogeny of the closely related species.At the same time,in the two trees,St genome,Y genome and P genome were well distinguished. Thus,the two genes can also be used to confirm the genomic constitution of species in which contain genome or genome combination of St,Y and P.