The Phylogenetic And Genetic Diversity Studies Of Agropyron Cristatum (L.) Gaertner (Poaceae:Triticeae) Based On Morphology And GBSSI Gene

As a perennial grass in the tribe Triticeae (Poaceae), Agropyron cristatum (L.) Gaertner is the type species within the genus Agropyron J. Gaertner, which is widely distributed in northern subtropics and temperate-frigid zone of Eurasia areas. Ag. cristatum constitutes a key component of the grassland, and plays an important role in improving the ecological environment. With tender stem and leaf, good taste for livestock and grow rapidly, Ag. cristatum has a potential forage grass with high values. In addition, Ag. cristatum is highly tolerant to various biotic and abiotic stresses, such as drought, cold, salinity stress and plant diseases like rusts, head scab, heavy metal stress and pathogens. All these features make it a valuable germplasm to improve the quality of Triticeae Crops. Previous studies for Ag. cristatum focused on the environmental construction, genetic breeding. However, studies on phylogeny, the genetic structure of population and cladistics in it are rarely reported. In this study,14 morphological traits of 47 Ag. cristatum species and GBSSI genes from 63 Ag. cristatum species and 25 related diploid genera were used to reconstruct the phylogenetic relationship between Agropyron and its related genera, and the phylogenetic relationship, genetic differentiation, morphological changes and population genetics in Ag. cristatum, finally the genetic diversity of Ag. cristatum was also analyzed in this study. The main results are as follows:1. Ag. cristatum has an abundant genetic diversity (π>0.05). Genetic differentiation measures was 0.058. Intra-population and inter-population genetic variation of Ag. cristatum were 5.8% and 94.2%, respectively. Combined the morphological data, it is suggested that intra-population genetic variation has effect on the genetic diversity of Ag. cristatum.2. In the molecular phylogenetic tree, Eremopyrum distan, Agropyron mongolicum and Taeniatherum caput-medusae grouped tegother with Ag. cristatum, supporting the suggestion that the P genome of Agropyron is closely related to the F chromosome group of Eremopyrum.3. Different accession of Ag. cristatum population from Central Asia were scattered in different subclades and grouped with those accession from Europe and East Asia, and these is a distinct relationship between Central Asia population and the population from other regions. These results indicate that Central Asia may be the origin center of Ag. cristatum. Ag. cristatum in Qinghai-Tibet Plateau is distinct from that in Central Asia and Europe, and most of them formed monophyletic group in the phylogenetic tree, suggesting that Ag. cristatum in Qinghai-Tibet Plateau were evolutionary distict.4. The population of Cental Asia might experience the obvious of population expansion and directional selection during its evolutionary history (Tajima’s D=-1.85001,P< 0.05). However, the Europe and East Asia population Tajima tests were negative with a non-significant difference, indicating a population stable genetic structure exist for the two populations.