| Based on the classification system of Flora of China, Roegneria C.Koch is the largest genus in Triticeae tribe including more than 130 species in the world. More than 70 species of Roegneria C.Koch are distributed in China and many of them are unique species. Roegneria in China with valuable characters such as resistance to adversity, long panicle, multi-grain, has provided a vast and valuable gene pool for crop improvement. Roegneria sinica.var.media Keng, a unique local species in China, is a perennial and self-pollination species, which is distributed widely in Shanxi, Gansu, Xinjiang and other provinces and regions. Perhaps because of the restriction of distribution region of R.sinica.var.media, there are little reports on genome constitution and diversity which exists between and within populations in R.sinica.var.media. In addition, a population of R.sinica.var.media which was likely photoperiod-temperature senstitive male-sterility was discovered by the former institute of Crop Germplasm,Chinese Academy of Agriculture Sciences when they investigated and collected Triticeas species distributed in Xingjiang in 2002. Therefore, the analysis of morphology, cytology and DNA of R.sinica.var.media would be of great significance for expounding genome constitution, the level of diversity, and establishing the scientific strategy of protection and application.In this paper, diversity of eleven morphological traits, the 2n number of chromosome and genome constitution, chromosome pairing of PMCs, diversity of SSR were studied using three population of R.sinica.var.media located in Xinjiang with 30plants chosen randomly from each population.The main results obtained as follows:1. The results of morphological diversity showed that genetic diversity index of the three populations was 1.991. The genetic diversity within populations was higher (91.76 %) than that of among populations (8.24%); and the diversity indexes in different sampling strategies increased along with the increasing of plant number. The diversity indexes were the highest when the sample number was 18. All together,the wild investigation and conservation of Triticeae plants in self-pollination should be based on population as a unit and the genetic diversity of populations could be represented with 18 individuals at least in each population.2. Analysis of genome constitution and chromosome translocations of somatic cell of three populations of R.sinica.var.media by genome in situ hybridization (GISH) showed that the three populations of R.sinica.var.media were all tetraploid, and it was the first time to suggest that genome constitution of R.sinica.var.media was StH; it was specially worth pointing out that spontaneous chromosomes translocations between St genome and H genome were observed, types of chromosomes translocations were various which took place both in the long arms and short arms, manly involved in two pairs of chromosomes, and some one pair. Translocation frequency (36.67%) of Z2291 was higher than Z2293 (6.67%) and Z2289 (0%), and types of Z2291 were also more abundant than Z2293 and Z2289, thereby there were more genetic variations existed in the population of Z2291. The results of chromosome structure variation showed that it could be communication between different genomes of the wild species in the process of evolution, and there were apparent variations existed in the level of genome in different individuals.3. Observation of chromosome pairing of PMCs showed that, (1) Chromosome pairings of the two populations of R.sinica.var.media were different and there were abundant genetic variation between and within the two populations. The mean chromosome configurations of the population Z2293 and Z2289 were 0.67 I + 13.59 II (9.99 rings + 3.59 rods) + 0.0032 III + 0.0424 IV and 1.55 I + 13.20 II (8.93rings + 4.27rods) + 0.0027 III + 0.0013 IV respectively; The mean number of bivalents and ring bivalents in per cell in the population of Z2293 was higher than Z2289, but univalents and rod bivalents in Z2293 was fewer than Z2289, and there were very significant differences of H univalents and ring H/H bivalents between the two populations, the stabilization of Z2293 was higher than Z2289; Genetic variation was mainly maintained within population(94.59%). Diversity index of Z2289 was a little higher than Z2293 in most configurations.(2) There was no remarked difference of configurations consitituted by St genome and H genome, but the mean number of bivalents and ring bivalents consitituted by St genome was higher than the number of H genome, on the contrary, the number of rod bivalents and univalents was lower than H genome, so the stabilization of St genome was higher than H genome; Pairing between heterogenous chromosomes were aslo observed, intergenomic bivalents, trivalents and quadrivalents could be consitituted by St genome and H genome. Pairing between heterogenous chromosomes showed that there were some homologous between St genome and H genome and it could be communication between heterogenous chromosomes. (3) Many heterogenous quadrivalents comsitituted by St genome and H genome were observed in the plant of 1-22 which was spontaneous translocation. The mean chromosome configuration of 1-22 was 0.23 I + 12.21 II (9.53 rings +2.67 rods) + 0.05 III+ 0.86 IV, the mean number of quadrivalents was 0.86 per cell. (4) Variations between and within the two populations showed that research of population as a unit would made out a comprehensive and scientific conclusion to the research of collecting of wild species, protection, origin and evolvement, and gene transfer from wild resource to wheat.4. The result of genetic diversity studied by SSR molecular markers showed that there were abundant genetic variations in the population of R.sinica.var.media, most genetic variations were maintained within population (80.51%) which was the same with the results of morphological traits and chromosome pairing. The total genetic diversity index of the three populations was 0.573, and there were some differences between the result of SSR genetic diversity which genetic diversity index of the population Z2291 (0.607) was the highest and morphological diversity which the population Z2289 was the highest.5. In this study, abundant genetic variation existed between and within the populations can be concluded by morphological traits, cytology and DNA molecular level, thus research based on population as a unit would be made a comprehensive and scientific conclusion; On the other hand, chromosome structure variation and pairing between heterogenous chromosomes showed that they could be communication between different genomes of the wild species in the process of evolution.
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