Genetic Diversity And Population Structure Of The Endangered And Endemic Recretohalophyte Reaumuria Trigyna Based On SSRs Developed From Trascription

Reaumuria trigyna (Reaumuria Linn genus, family Tamaricaceae) is an endangered and endemic species distributed in western Inner Mongolia, China. As a rare and relict ancient Mediterranean plant, it is only distributed in Inner Mongolia and Ning xia region in China. One of the main threats that R. trigyna faced is habitat fragmentation. Fragmentation decreases habitat sizes and increases distances between habitats and populations. These physical changes are generally thought to decrease population sizes and gene flow, resulting in loss of genetic diversity and an increase in differentiation. Therefore, analysis the genetic diversity and population structure of R.trigyna, which can get an in-depth knowledge of it’s evolutionary potential and adaptive capacity. With the 10 SSR markers developed from R. trigyna transcriptome data, this study selects the 7 populations of R. trigyna distributed in the saline desertification region of western Inner Mongolia and 3 populations in Ningxia as the research objects, and conducts researches on population genetic diversity and genetic structure of the 200 R. trigyna individuals of the 10 populations, thus providing reference for the protection of endangered species. The results of the study are as follows:1. This experiment searched and devoloped 10 polymorphic SSR loci from transcriptome of R. trigyna with the Illumina sequencing technology. Made primer commonality evaluation for the 10 pairs of polymorphic primers of R. trigyna in Reaumuria soongorica genomic DNA, and the results indicated that, the three pairs of primers had obvious identification effect in R. soongorica and could be used in R. soongorica study.2. A neutral site inspection was made to 10 SSR loci, and the results showed that within the 95% confidence interval, seven loci were neutral evolution loci, while three lociwere balancing selection acting loci.3. Altogether 29 polymorphism loci were detected from 10 pairs of SSR microsatellite primers, and the polymorphism information content value of these SSR loci ranged from 0.2352 to 0.5019. Among them, the locus (GCT)6 was a high polymorphic marker.4. The genetic diversity analysis of R. trigyna obtained, that the genetic diversity in R. trigyna populations was low, the genetic variation within populations was greater than the variation between populations, the genetic differentiation between populations was great, and genetic drift and serious inbreeding phenomenon existed.5. The PCA analysis results were consistent with the individual clustering results of STRUCTURE and UPGMA. Their results all proved that all individuals were divided into two subgroups, so it was estimated that the two subgroups of R. trigyna were likely the representative residues of the shelter in glacial period.6. Feasible protection measures are put forward in view of the current growth situation of R. trigyna:strengthen the protection consciousness for residents and endangered plants and set up protection zone; spread seeds of R. trigyna regularly in the protected area and increase its growth area; give in situ protection for the R. trigyna populations which can’t be included in the protected area; conducted gene flow maintenance manually, conducted a large number of experiments and developed the optimal system of germination of the species in the wild.