Origin Of Natural Hybrids Of Roegneria Based On DMC1 And Rps16 Genes(Poaceae,Triticeae)

Natural hybridization among species is a common phenomenon in plants.It is widely involved in plants differentiation and is an important mechanism for the formation and maintenance of biological diversity.Among Triticeae species,natural hybridization between different genera or species also occur frequently.Based on the morphological and cytogenetic analysis of 57 Roegneria natural hybrids found in Hongyuan,Sichuan,this study adopted the nuclear gene DMC1 and the chloroplast gene rps16 to analyze the putative parents and origin of these 20 natural hybrids.This study will be providing theoretical basis for the use of these natural hybrids in forage and ecological grass breeding.The main results were showed as follows:1.40 DMC1 sequences and 20 rps16 sequences were cloned and sequenced from 20 natural hybrids.The length of the DMC1 sequence varied from 998 bp to 1004 bp,and the length of the rps16 sequence was 830-831 bp.2.20 natural hybrids obtained two homologous sequences of DMC1 genes,which were clustered in the St genome and the Y genome in the phylogenetic tree.Therefore,it can be determined that the genome compositions of the 20 natural hybrids are all St Y,which is consistent with cytology research.3.Phylogenetic analysis of 5 RH1 natural hybrids and their putative parents based on the single copy nuclear gene DMC1 showed that 5 natural hybrids and R.turczaninovii constituted a clade on the St clade,while 5 natural hybrids and R.stricta were clustered in a branch on the Y clade.These results showed that the 5 natural hybrids have close relationships with Roegneria stricta and R.turczaninovii and these two species might be the parents of these hybrids.And phylogenetic analysis of chloroplast gene rps16 showed that 5 hybrids were grouped with R.stricta,indicating that R.stricta might be the female parent of these hybrids.4.Phylogenetic analysis of 15 RH2 natural hybrids and their putative parents based on the single copy nuclear gene DMC1 showed that 13 hybrids and R.turczaninovii are constituted a clade on the St clade,2 hybrids and R.stricta are formed a branch,while 11 natural hybrids and R.stricta were clustered in a branch on the Y clade,3 hybrids and St YH species are formed in a branch.These results showed that the 15 natural hybrids have close relationships with Roegneria stricta and R.turczaninovii,indicating that these two species might be the parents of these hybrids,and 3 natural hybrids may contain the infiltration of the foreign St YH genome.And phylogenetic analysis of chloroplast gene rps16 showed that 15 hybrids were grouped with R.turczaninovii,indicating that R.turczaninovii might be the female parent of these hybrids.