| Abstract: The wheat tribe Triticeae Damort., in the subfamily Pooideae, includes three of the most important cereal crops, i.e., wheat, barely, and rye, as well as many economically valuable forage grasses, i.e., genus Elymus L. and Pseudoroegneria (Nevski) ?.L?ve. The genus Pseudoroegneria is an important perennial genus in Triticeae (Poaceae). As a mainly germplasm resources of tribe Triticeae, it covers excellent genomes which are resisted to disease, insect, and circumstance intimidation. The St genome which is the fundamental genome of Pseudoroegneria is a St donor of more than 150 taxa grasses, such as Elymus L., et al. Knowledge of phylogeny of Pseudoroegneria is helpful to realize the tribe Triticeae.In this research work, we used the sequences of nuclear genes (ITS, Adh1, Adh2, Adh3) and chloroplast DNA (trnL-F) to analyze the phylogenetic relationship in Pseudoroegneria and its relatedness with geographical distribution, and to explore the origin of tetraploid Pseudoroegneria species and Douglasdeweya wangii species. The main results are summarized as follows:1. Based on multiple-gene sequence data, including one chloroplast trnL-F gene, one ITS fragment of nuclear ribosomal DNA, and three low copy nuclear gene Adh1, Adh2, and Adh3, the phylogenetic relationships in Pseudoroegneria was inferred. The analyses of on multiple-gene sequence data have produced the same results. The Pseudoroegneria was monophyletic, and formed a sister relationship with the P-W genome species.2. The phylogenetic trees based on multiple-gene data of diploid Pseudoroegneria species showed the species distributed in China all grouped together. Similarly, species distributed in Russia all grouped together, also species distributed in Iran all grouped together. These topology showed in phylogenetic tree indicated the correlation between geographic distribution and species relationships exists.3. Some diploid Pseudoroegneria accessions in contained two or more types of nuclear genes, and clustered in different clades in phylogenetic trees. Compared with the cytogenetic data, these diploid Pseudoroegneria accessions were presumed to experience hybridization and introgression.4. Phylogenetic analyses of tetraploid Pseudoroegneria accessions showed that they are grouped in different clade in phylogenetic trees, which indicate some tetraploid Pseudoroegneria species were independent origin and experienced recurrent hybridization. In phylogenetic trees, the same species with different polyploidy was not grouped together, which indicate the origin of tetraploid Pseudoroegneria accessions had some difference distinguished from the traditional origin of autopolyploids.5. P.tauri and P.libanotica are endemic to Western Asia and Caucasus. These two species had similar genome types, similar morphological characteristics as well as overlapping in the distribution. The phylogenetic relationships in showed these two species were clustered together and immingled each other. We prefer theses these two species to be one species P.libanotica.6. The trnL-F sequences revealed an especially close relationship of Pseudoroegneria to all D. wangii accessions studied, which indicate Pseudoroegneria was the maternal donor of D. wangii. In trnL-F tree, D. wangii , P.tauri 48, and P.tauri 49 were grouped together, which indicate these two accessions were the maternal donor candidates of D. wangii.7. Based on restriction fragment length polymorphism (RFLP) of the Adh sequences, a method to identify the species with the St, P, W, H, StYH, StYP, and StYW genomes was proposed. The method is rapid and convenient, and the experimental procedure includes four steps: (1) amplifying nuclear Adh genes with universal primers; (2) purifying and cloning PCR products; (3) digesting plasmids with restriction enzymes that identify a given genome; (4) running the digested products on an agarose gel and identify the sample based on the restriction profiles.
|
PDF Full Text Request