| There are more than two hundred genera of the family Compositae in China,including two thousand species. Some species have high potential value for medicine,industry, flowers, forage, etc. Among them, forage resources are very rich(more than eighty genera and three hundred species) and widely distributed, including Saussurea DC., Bidens L., Artemisia L., Aster L., Taraxacum F. H. Wigg., etc. Forage germplasm resource refers to genetic materials of all forage grass and turf-grass species. The present forage germplasm resources are usually stored in the form of seeds. However, they are very often to be mis-identified and need to be re-identified with correct names. This study investigated the herbarium specimens and wild population of forage plants and established identification system of Chinese forage plants, based on morphological characters of achenes and DNA barcoding(ITS,psbA-trnH and rbcLa). The results provide information for accurate identification of forage grass species and basis for the entry-exit inspection and quarantine of Compositae plant seeds. The implications of this study have played important roles in preventing alien plant invasion and controlling of lossing plant germplasm resources of Compositae.1 Achene morphology study of forage plants of CompositaeThe achene materials mainly came from the National Germplasm Repository and others were collected by researcher. There were more than 300 taxa in total,belonging to 11 tribes(Astereae, Inuleae, Heliantheae, Cichorieae, etc.). Achene features, such as the shape, size, surface ornamentation, color, beak, hilum and pappus, were observed, calculated, photographed and identified, using microscope graticules and anatomical lens. A key of forage plants of Compositae was made up based on morphological features of achene.The research shows that characters such as the shape and size of achenes, ribbed,beaked achene or not, are useful to identify forage plants at genus level. Other features,such as the number of ribs, the length of the beak, the features of surface and hilumare useful to identify achenes at the level of species.2 DNA barcoding study of forage plants of CompositaeITS sequences, psbA-trnH intergenic spacer and rbcLa gene sequences were used as DNA barcodes to construct phylogenetic relationships in forage plants of Compositae. Some DNA sequences were obtained by isolation DNA from identified species, PCR amplification and Sanger sequencing of the three barcodes. Other sequences were from GenBank database. In this study, we comparaed phylogenetic trees based on ribosomal DNA sequences and chloroplast DNA sequences. The results show that the phylogenetic relationships based on psbA-trnH+rbcLa sequences are more reliable than the evolutionary relationships based on ITS or single chloroplast DNA barcode at the genus and species levels. |
