Genetic variability and population structure of endangered Panax ginseng in the Russian Primorye

<p>Abstract</p> <p>Background</p> <p>The natural habitat of wild <it>P. ginseng </it>is currently found only in the Russian Primorye and the populations are extremely exhausted and require restoration. Analysis of the genetic diversity and population structure of an endangered species is a prerequisite for conservation. The present study aims to investigate the patterns and levels of genetic polymorphism and population structures of wild <it>P. ginseng </it>with the AFLP method to (1) estimate the level of genetic diversity in the <it>P. ginseng </it>populations in the Russian Primorsky Krai, (2) calculate the distribution of variability within a population and among populations and (3) examine the genetic relationship between the populations.</p> <p>Methods</p> <p>Genetic variability and population structure of ten <it>P. ginseng </it>populations were investigated with Amplified Fragment Length Polymorphism (AFLP) markers. The genetic relationships among <it>P. ginseng </it>plants and populations were delineated.</p> <p>Results</p> <p>The mean genetic variability within populations was high. The mean level of polymorphisms was 55.68% at the population level and 99.65% at the species level. The Shannon's index ranged between 0.1602 and 0.3222 with an average of 0.2626 at the population level and 0.3967 at the species level. The analysis of molecular variances (AMOVA) showed a significant population structure in <it>P. ginseng</it>. The partition of genetic diversity with AMOVA suggested that the majority of the genetic variation (64.5%) was within populations of <it>P. ginseng</it>. The inter-population variability was approximately 36% of the total variability. The genetic relationships among <it>P. ginseng </it>plants and populations were reconstructed by Minimum Spanning tree (MS-tree) on the basis of Euclidean distances with ARLEQUIN and NTSYS, respectively. The MS-trees suggest that the southern <it>Uss</it>, <it>Part </it>and <it>Nad </it>populations may have promoted <it>P. ginseng </it>distribution throughout the Russian Primorye.</p> <p>Conclusion</p> <p>The <it>P. ginseng </it>populations in the Russian Primorye are significant in genetic diversity. The high variability demonstrates that the current genetic resources of <it>P. ginseng </it>populations have not been exposed to depletion.</p

Variation in the number of nucleoli and incomplete homogenization of 18S ribosomal DNA sequences in leaf cells of the cultivated Oriental ginseng (Panax ginseng Meyer)

Background: Wild ginseng, Panax ginseng Meyer, is an endangered species of medicinal plants. In the present study, we analyzed variations within the ribosomal DNA (rDNA) cluster to gain insight into the genetic diversity of the Oriental ginseng, P. ginseng, at artificial plant cultivation. Methods: The roots of wild P. ginseng plants were sampled from a nonprotected natural population of the Russian Far East. The slides were prepared from leaf tissues using the squash technique for cytogenetic analysis. The 18S rDNA sequences were cloned and sequenced. The distribution of nucleotide diversity, recombination events, and interspecific phylogenies for the total 18S rDNA sequence data set was also examined. Results: In mesophyll cells, mononucleolar nuclei were estimated to be dominant (75.7%), while the remaining nuclei contained two to four nucleoli. Among the analyzed 18S rDNA clones, 20% were identical to the 18S rDNA sequence of P. ginseng from Japan, and other clones differed in one to six substitutions. The nucleotide polymorphism was more expressed at the positions 440–640 bp, and distributed in variable regions, expansion segments, and conservative elements of core structure. The phylogenetic analysis confirmed conspecificity of ginseng plants cultivated in different regions, with two fixed mutations between P. ginseng and other species. Conclusion: This study identified the evidences of the intragenomic nucleotide polymorphism in the 18S rDNA sequences of P. ginseng. These data suggest that, in cultivated plants, the observed genome instability may influence the synthesis of biologically active compounds, which are widely used in traditional medicine