| The Triticeae is a very important group in Poaceae, which not only includes some important cereal crops, such as wheat, barley and rye and so on, but also comprises many forage grasses with high values in economy and ecology. The tribe Triticeae, including about 350-450 species distributed in all over the world, especially in the north temperate zone and Mediterranean. The Elymus L. is a important perennial genera in Triticeae, which main distributed in Asia and North American and also distributed in Europe, South American and Australia. In China,12 species and 1 subspecies of Elymus were recorded in the Flora of China (Chinese version), which main distributed in Northwest, North China, Northeast and Southwest. In addition, Many Elymus species are good forage grass and are the main contents of grassland and meadow, which have high feeding value. However, there are some controversies in circumscription of related species and genera and phylogenetic, which is also a hotpot for grass taxomomists. At present, the main research area focus on circumscription of Elymus, the genome constitution of many Elymus species, the origin of Y genome and the differentiation of St genome and so on.In this study, we carried out the phylogenetic analysis of Elymus and related diploid species based on multiple copy nuclear ITS sequences, single copy nuclear DMC1 gene sequences and chloroplast trnH-psbA sequences. Data from these molecular phylogenetic evidences were analysed together with structures of endosperm cell and Genetic polymorphism of gliadin. The objectives were:(1) to elucidate the phylogenetic relationships in Chinese Elymus; (2) to reveal the origin of genome in Elymus, especially the origin of Y genome; (3) to identify the maternal genome donor to Chinese Elymus. The main results are as follows:1. The nuclear ribosomal internal transcribed spacer (ITS) sequences were analyzed for 41 accessions of Elymus representing 10 species, together with 17 diploid taxa from 5 monogenomic genera. The phylogenetic analyses (Neighbor-Joining) supported two major clades (St and H). Sequence diversity and genealogical analysis suggested that (1) Elymus species were unambiguously closely related to Pseudoroegeria; (2) Pse. stipifolia might be serve as the St genome donor of polyploid Elymus species; (3) the Y genome might be originated from ancestral lineage of Pseudoroegneria (St); (4) the ITS sequences of Elymus were evolutionarily distinct and may clarify parental lineages and phylogenetic relationships in Elymus.2. The disrupted meiotic cDNA1 (DMC1) sequences were analyzed for 10 Elymus species, together with 34 diploid taxa from 13 monogenomic genera. The phylogenetic analyses (Neighbor-Joining) supported three major clades (St, Y and H). Sequence diversity and genealogical analysis suggested that (1) Elymus species are unambiguously closely related to Pseudoroegeria and Hordeum. Pseudoroegeria and Hordeum might be serve as the St genome and H genome donor of polyploid Elymus species; (2) Phylogenetic analyses separated the Y sequences from the St sequences, it confirmed that St and Y genome in Elymus species have originated from different donors; (3) the St genome of Elymus had several origins and diverse species of Pseudoroegneria might have taken part in the formation of polyploid species of Elymus; (4) the DMC1 sequences of Elymus are evolutionarily distinct, and it can clarify parental lineages and phylogenetic relationships of genera Elymus.3. To investigate the phylogenetic relationships among Elymus and related diploid genera, the maternal donor of Elymus, and the evolutionary history of polyploid Elymus species, chloroplast trnH-psbA sequences were analyzed for 24 accessions of Elymus representing 10 species, together with 11 diploid taxa from 6 monogenomic genera. Sequence diversity and genealogical analysis suggested that Pseudoroegneria was the maternal donor of the polyploid Elymus; and some Elymus species showed multiple origin and experienced recurrent hybridization.4. The endosperm cells of 11 Triticeae species which belong to Elymus, Pseudoroegneria, Hordeum or Agropyron, were surveyed in this paper. The results showed that significant variations existed in the size, forms and quantity of endosperm cells in those species. The differences in genera are smaller than those in species, indicating that the characters of endosperm cells have less value in the systematic studies of those genera than in the studies of those species in Triticeae.5. The gliadin genetic plomophism among 12 accessions of 6 species in Elymus L. were analyzed by using acid polyacrylamide gel electrophoresis (A-PAGE). The results showed as follows:(1) 11 types of gliadin patterns were obtained from the tested materials and materials had their unique patterns respectively. A total of 17 gliadin bands were separated by ellectrohoresis, of all showing polymorphism, which amounts to 100%; (2) Distinct gliadin genetic variations were presented among the populations. The gliadin genetic variations among different species were more abundant than that of different accessions, and it revealed that the gliadin patterns can be used as a fingerprint to survey different materials in Elymus L.; (3) The relationships among species in Elymus L. according to gliadin data are basically comparable with that obtained from morphological data, so that the gliadin patterns data can be used to investigate genetic variation and biosystematic relationships among species in Elymus L. |
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