The Phylogenetic Studies Of Genus Anthosachne(Poaceae:Triticeae)

Anthosachne Genus is the endemic spiece of Oceania, it is an important perennial of Poaceae Triticeae. The chromosome numbers in Anthosachne was assigned as StYW, where W was presumed to be originated from Australopyrum, and the StY distributed in Asia that presumed to be originated from Roegneria, they formed allohesaploid by hybrid. According to the principle of modern genetic systematic, it only contained Anthosachne Anthosachne rectisetus and Anthosachne scaber. However, according to morphology and reproductive behavior of some of the differences, it can be divided into three groups. Currently, it is divided into a number of species or subspecies, or variants by several scholars, these are all need to determine its system division based on the results of biological experiment.The plants of Anthosachne rectisetus and Anthosachne scaber are mainly located in Australia, and New Zealand. Australia was early separated with the other continents, and it was long-term isolated, it caused that marine blocked the spread of organisms. There was no large fold movement occurred after the formation Australia, In Australia, the crust has been relatively stable, natural conditions relatively simple and the species were slowly evoluted. Studies on the relationships between island plants Anthosachne rectisetus and Anthosachne scaber with their diploid donor species and tetraploid donor species, the process of evolution of island species and mainland species contact and islands of plant evolution single origin are all less.In this studv, the plants of Anthosachne rectisetus and Anthosachne scaber and the diploid and tetraploid donor species are as the research materials, studying them to learn from the morphology, molecular systems, and explore the genetic relationship between these two species, as well as for the test material as the island plants and distribution of the evolutionary relationship between the diploid donor species and the tetraploid species on the mainland. The main results are as follows:1. A comparative analysis of morphological characteristics of34species of Anthosachne rectietus and Anthosachne scaber showed that, theri genetic material have had exchanged frequently, which caused the high similarity of morphological traits between them.2. Experiments obtained60chloroplast sequences of rbcL, trnH-psbA and40nuclear sequences of Accl in Anthosachne rectisetus and Anthosachne scaber and the diploid species and tetraploid species which contain StY genome. The three sequences builded the Network. The results show that(1) An. rectisetus and An. scaber got together with Pseudoroegneria that contained the St genome, and formed a close lineage relationship with Pse. stipifolia,while the Pseudoroegneria diploid species of Eurasia were far away from the pedigree. The experimental results suggested that the Pse. stipifolia involved in the formation of Genus Anthosachne.(2) Comparative analysis of orthologous based on gene sequences between Anthosachne and Roegneria that contained StY genome formed the Networks were all showed that different tetraploid species plants of Roegneria and different plants of Anthosachne formed different branches, the results showed that these two genera have closeed affinities, at the same time, it speculated that Roegneria as the donor involved in the formation of Anthosachne species.(3) The plants of Anthosachne reformed many haplotypes. the phenomenon that different orgins of Anthosachne species shared the same haplotypes speculate the genetic variation is small of Anthosachne and it maybe exist interspecific hybridization.(4) The mutation number of sites of Anthosachne and the diploid, tetraploid species are more than the interspecific or intraspecific, we speculate it exists genetic differentiation between Anthosachne and its donor species in Eurasia, this implied the Anthosachne had have reformed a independent branch.3. In the results of genetic polymorphism analysis, the polymorphism mean of Anthosachne scaber were a little larger, and the genetic diversity were increased, it perhaps because the plans of Anthosachne rectisetus have introgressed into the plants of An. scaber: however, the polymorphism mean of Anthosachne rectisetus wase lower than the diploid species that contained St genome.we could speculate Anthosachne rectisetus suffered a genetic bottleneck in the evolutionary, and it supports Anthosachne have unique island envolution style.