Study On Genetic Diversity Of Leymus Racemosus(Lam.) Tzvel

Materials of Leymus racemosus(Lam.) Tzvel both between and within groups were collected form Xinjiang Aletai area. Leymus racemosus was studied by the following aspeets in this paper: morphological markers, karyotype analysis and gliadin markers. Main results obtained were as follows:(1) 16 morphological traits were adapted to study morphological diversity of 5 native populations of Leymus racemosus(Lam.) Tzvel collected form Xinjiang Altay region. The coefficient of variation analysis showed that general average was 18.147% within population, 10.045% among the populations. There was abundant genetic diversity(H′=1.899) among these populations in traits, the genetic variation within populations(87.41%) was greater than that among populations(12.59%). The results of principal components analysis showed, plant height, the first internode length, flag leaf length, flag leaf width, ear length and width, etc. 12 morphological traits were the main sources of variation of Leymus racemosus(Lam.) Tzvel. According to the cluster analysis, the 5 populations of Leymus racemosus(Lam.) Tzve could be divided into three groups; 16 morphological traits were clustered into 4 groups at genetic distance of 5, The first group mainly were the first internode length, panicle length, flag leaf length and spike node number. The second category were the stem diameter, spikelet width, inner glume length, outer glume length, palea length and lemma length. The third and the forth classes were plant height and number of spikelets. The results showed that abundant phenotypic diversity of Leymus racemosus(Lam.) Tzvel had important significance for its conservation and utilization.(2) Karyotypes of materials of 5 Leymus racemosus(Lam.) Tzvel populations of Xinjiang Aletai area have been studied in the paper. Optical microscope was used to observe chromosome of the different populations material and chromosome in different individuals within the same population. The experiment was initially analyzing data in chromosomal karyotype of the populations and within the same population. Karyotype analysis results showed that their karyotypes were similar and belonged to 2A, three of them has SAT in the populations, the karyotype formulae were as follows: P1: 2n=4x=28=24m(2SAT)+4sm(2SAT); P4: 2n=4x=28=20m(2SAT)+8sm; P5: 2n=4x=28=20m+8sm(2SAT), and the others: P2: 2n=4x=28=26m+ 2sm; P3: 2n=4x=28=22m+6sm. The results suggested that there were chromosome differentiations of the populations not only with the SAT existence or not, but also with the extent in arm ratio, length ratio, asymmetry index. The karyotype formulae of the same population was 2n=4x=28=22m+6sm, belong to 2A. There were 11 pairs of metacentric chromosomes and 3 pairs of submetacentric chromosome, not with sat chromosome. The results showed that different populations of Leymus racemosus occurs some changes in karyotype, tiny difference within the same population.(3) Acid polyacrylamide gel electrophoresis(A-PAGE) was used to detect the gliadin genetic diversity of 5 populations of Leymus racemosus(Lam.) Tzvel and within population, The results showed as follows:(1)5 populations of Leymus racemosus separated a total of 19 gliadin bands by electrophoresis, the common band number was two, 89.47% of them were polymorphic. A total of 17 gliadin bands were separated by electrophoresis of within population, 7 common bands of them, the polymorphic rate was 58.82%, polymorphism of within population less than among populations.(2)Four electrophoretic zones(α、β、γ、ω) Shannon index range was 0.3467 to 0.4000, average value 0.3727. Nei-Li genetic similarity coefficient(GS) variation range was 1.5837 to 1.7385, average value 1.6594. The Nei’s genetic similarity coefficient of the tested accessions ranged from 0.429 to 0.733, and the average Nei’s coefficient was 0.554.Moreover, the similarity coefficient between P5 and P1 was the smallest, and the genetic distance was the biggest, which indicated that the genetic relationship of the two regions was the furthest, The genetic similarity coefficient of P2 and P4 was the largest, and its genetic distance was least, which indicated that the relationship between the two accessions was closest. Further clustering analysis showed that, when the GS value was 0.62 for the level test, 5 populations can be clustered into 3 categories, similar habitat populations clustered together, showed certain regularities of distribution, indicating that there was a correlation between genetic divergence and geographical environment among the groups.