4.2 | Origin of hybrids RH1 and RH2
Single copy nuclear gene is inherited from both parents and is rarely affected by concerted evolution. Therefore, it is used as an ideal DNA sequence in the analysis of plant molecular phylogeny to study the relationship of related species, polyploid plant phylogenetic relationship, speciation history of allopolyploid, source of species genome donor, generation of hybridization events, and gene introgression of polyploid species have significant advantages (Sang, 2002; Tang et al., 2017). In the present study, we performed phylogenetic analyses of the hybrids, the associated species (R. stricta, R. turczaninovii, R. grandis, E. sibiricus) and other Triticeae species with different genomic compositions. Two distinctDMC1 copies of the sequences from hybrids, R. stricta,R. turczaninovii and the other Triticeae species growing nearby were divided into St and Y clades (Figure 8). In theSt clade, 15 hybrids sequences and R. turczaninoviiformed a subclade (BS=51%, PP=1.00). In the Y clade, 15 hybrids sequences, R. turczaninovii and R. stricta formed a subclade (BS=64%, PP=0.83). The results of phylogenetic analysis based on nuclear gene DMC1 showed that natural hybrids have close relationships with R. stricta and R. turczaninovii, and they all contained St and Y genomes. The results were consistent with cytological studies. Phylogenetic analyses based on rps16 sequence showed 5 hybrids RH1 sequences were grouped with R. stricta (BS=64%, PP=0.97), 10 hybrids RH2 sequences were grouped with R. turczaninovii(BS=87%, PP=1.00). Furthermore, hybrids RH1 were collected fromR. stricta, hybrids RH2 were collected from R. turczaninovii. So, R. stricta was the female parent of the hybrids RH1, R. stricta was the female parent of the hybrids RH2.
Therefore, based on the results of cytological and phylogenetic analysis, we suggested that R. stricta and R. turczaninovii were the female and male parents of the hybrids RH1; R. turczaninovii and R. stricta were the female and male parents of the hybrids RH2.