| Kengyilia Yen et J.L.Yang, a polyploid perennial genus in the Triticeae (Poaceae:), which was first established with the type species of Kengyilia gobicola by Yen Chi and Yang Jun-liang in1990. Many species of Kengyilia are not only main components of grass lands and grass marshlands, but also fine varieties of herbage that can provide economic value. Because its growth environment is very bad, Kengyilia species obtain the characteristics of alkali-resistance, drought and cold tolerance, disease resistance for surviving. The excellent characteristics could support abundant germplasm resources for the genetic improvement and further selective breeding of Triticeae crop and forage grasses.Cytogenetic evidence suggested species of Kengyilia are allohexaploid (2n= 6x= 42) with the StYP genomes. The StY genome of Kengyilia originated from Roegneria, while the P genome was from Agropyron. The St genome was derived from the diploid species of Pseudoroegneria, and the diploid donor species for Y genome has not yet been found. So far, the systematic position of Kengyilia has been recognized. But its systematic affinity, origin of the species, system classification and evolutionary lines are remaining controversial for further study today.In the study, phylogenetic relationships and maternal donor of Kengyilia species and their closely related species were analyzed based on the chloroplast DNA regions trnT-L sequence and single-copy nuclear DNA DMC1 sequence. The objectives of this study were to infer the maternal donor of Kengyilia species, and to reveal phylogenetic relationships between the species of Kengyilia and their closely related species. The main results showed as following:1. In the phylogenetic tree based on trnT-L gene sequence, diverse species of Kengyilia were respectively clustered with species of Roegneria, Pseudoroegneria and Agropyron. It showed that Kengyilia melanthera was related to species of Agropyron, whereas the other species were related to species of Pseudoroegneria and Roegneria. i.e., The P genome of Kengyilia was from the diploid species of Agropyron, while the St genome was derived from Pseudoroegneria. Moreover, Pseudoroegneria libanotica was related to Roegneria sinica and Roegneria grandis. So we could guess that the St genome of Roegneria originated from Pseudoroegneria.2. In the phylogenetic trees based on trnT-L and DMC1 gene sequences, four species of Pseudoroegneria (Pse. libanotica, Pse. stipiflolia, Pse. spicata and Pse. strigosa) did not form a monophyletic group, the result manifested that genetic material of St genome had changed, the St genome of Kengyilia had several origins and diverse species of Pseudoroegneria minght have taken part in the formation of polyploid species of Kengyilia.3. In the phylogenetic tree based on DMC1 gene sequence, The St genome was clustered with P genome firstly, then clustered with Y genome, as a result, We could consider that the relationship between St genome and P genome was closer than the relationship between St genome and Y genome, and Y genome was not transformed from St genome.4. In the phylogenetic tree based on DMC1 gene sequence, Kengyilia was not clustered with Peridictyon and Dasypyrum on the Y-branch, which indicated that neither Xp genome of Peridictyon nor V genome of Dasypyrum was related to St genome of Kengyilia.5. In the phylogenetic tree based on DMC1 gene sequence, most species of Kengyilia clustered together on the Y-branch, which implied Y genome of these Kengyilia species were highly homologous. But in the study, the diploid donor species for Y genome was not found. Meanwhile, two different kinds of Y genome sequence were separated from K. melanthera, K. kokonorica, K mutica and K. thoroldiana. According to the result, we could surmise that introgressin hybridization had happened in the four species of Kengyilia. |
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