Study On The Genetic Structure And Clonal Diversity Of Psammophyte Leymus Racemosus Germplasm Resources

This study used a fluorescent AFLP molecular marker to conduct a genetic diversity analysis in six natural populations(a total of 117 samples) located in Altay Distract, Xinjiang.To understand the genetic background of psammophyteLeymus racemosus germplasm resourcesin a larger scale, and study the genetic variation among and within six populations as well as the spatial distribution pattern. The purpose of this section is to provide a reference which is to prevent wind and sand and improve wheat genetic.Meanwhile, to understand the dynamics and evolution of the population in a smaller scale, a molecular marker ISSR was used to analysis the clonal diversity and structure for 6 populations(a total of 170 samples) of L. racemosusin two of the typical habitats(sand and dunes). The main results were as follows:1?The genetic variation for 6 populations of psammophyte L. racemosusThe analysis of genetic variation for 6 populations of psammophyte Leymus racemosus showed that the H and I levels of the selected six pairs of fluorescent selective amplified primers at the population level were 0.177 and 0.288, respectively. The PPL amplitude in the six types of L. racemosuspopulation ranged from 72.97~85.89%, the highest PPL was reported in BT population(85.89%). While the H and I amplitudes ranged from 0.159~0.190 and 0.258~0.311, respectively; the highest H and I were reported in BEJ population(H=0.190, I=0.311). These results indicated thatL. racemosus in BT and BEJ populations have a higher genetic diversity and further analysis showed that there was no obvious genetic variation among 6 populations of psammophyteL. racemosus2?The genetic structure for 6 populations of psammophyte L. racemosusTheir genetic structure is mainly reflected in the following aspects: Fst amplitude ranged from 0.023~0.096 and average Fst was 0.078; Nm amplitude ranged from2.520~10.568, average value was 2.960>1, indicating that due to genetic differentiation caused by genetic drift can be blocked by genetic flow in these populations. STRUCTURE and PCoA clustering results showed that three populations of HBX, HBN and HBD were clustered into one group, while BEJ, FH and BT were clustered into another group. Further analysis on the genetic and geographic distance between six types of Leymus racemosus populations reported a non-significant positive relationship(P>0.05).3?Clonal diversity of sand-dune L. racemosuspopulationsNTSYS analysis showed that there were 98 clones detected in twopopulations of L. racemosus. The average clone size(Nc), average genotype frequencies(PD), the average Simpson index(D) and the average Farger evenness index(E) were 1.862, 0.562, 0.882 and 0.676, respectively. These results indicated a higher clonal diversity in L. racemosus, especially for the HBX population which had three plots with 75 samples and 44 genets. Its Nc value was small(the average of each clone that contained the number of ramets was less than the number of HBN.HBX in sands had a more obvious clonal diversity than HBN in dunes, because of a higher amplitude and average Simpson index(D)(0.923~0.940, 0.932; 0.642~0.978, 0.844) as well as a higheramplitude and average Fager evenness index(0.686~0.856, 0.764; 0.318~0.818, 0.609). Both genotypes were distributed locally. Leymus racemosus populations distributed in sands and dunes are polyclonal populations because they contains numerous of genotypes. Each collection site was present with dominant clonal.4?Clonal structure of L. racemosus populations distributed in sands and dunesGenet diffusion distance of three plots in HBX were ranged from 1.000~3.610 m, with less branched, a long spacer and rapidly extending horizontally along a straight line. Its clonal architecture was guerilla. While the genet of maximum diffusion distance in HBN was 1 m(because the plaque area was 1 m2); the ramet was closely arranged with a small spacer and obvious branch but no clear direction, forming irregular line bundle. Therefore, the clonal architecture in HBN was phalanx. These results showed that there was a significant difference between the L. racemosus populations distributed in sands and dunes, which may be due to their adaptation to the heterogeneous habitats.