Aim: The mating system of Panax ginseng, genetics and ontogenetic structure of its natural populations of Primorye (Russia) were investigated. Methods: Genetic diversity was assessed using allozyme and the fluorescently based automated amplified fragment length polymorphism (AFLP) and simple sequence repeats (SSR) markers. Results: Total genetic diversity at species level is low with allozyme assay (0.023), and high with AFLP (0.255) and SSR (0.259) methods. It is observed within populations according to allozyme (>99%), AFLP (>85%), and SSR (>73%) assays. The indices of genetic variability distribution point out the re-colonization of the Sikhote-Alin by ginseng plants from southern refuges during the warming period in the early Holocene. The capability of ginseng plants to cross-and self-pollinate was shown and the assumption that Panax ginseng is a facultative apomictic plant was confirmed. The reproductive system of ginseng possesses high plasticity and stability of the fertilization process that help the species to survive in stress conditions. Disturbances caused by external or internal factors can be reduced due to the morphogenetic potential of ginseng ovule or apomictic embryo development. Analysis of life stages structure of ginseng populations demonstrates that all of them are not full-constituents because some life stages are absent or occur rarely. Conclusion: In all 3 populations, virgin and young generative individuals are predominant. This means that populations studied are viable and the reintroduction of natural ginseng population is possible yet. Key wordsPanax ginseng; natural population; genetic d i v e r s i t y ; m a t i n g s y s t e m ; e m b r y o l o g y ; allozymes; AFLP; SSR

Expression of the Agrobacterium rhizogenes rolC gene in Panax ginseng callus cells results in formation of tumors that are capable to form roots. The selection of non-root forming tumor clusters yielded the embryogenic 2c3 callus line, which formed somatic embryos and shoots independently of external growth factors. Although the 2c3 somatic embryos developed through a typical embryogenesis process, they terminated prematurely and repeatedly formed adventitious shoot meristems and embryo-like structures. A part of the shoots and somatic embryos formed enlarged and fasciated meristems. This is the first indication of the rolC gene embryogenic effect and, to our knowledge, the first indication that a single gene of non-plant origin can induce somatic embryogenesis in plants.

Populations of predominantly selfing plant species often show spatial genetic structure but little is known whether epistatic gene interactions are spatially structured. To detect a possible epistatic effect and a spatial scale at which it operates, we created artificial crosses between plants spanning a range of fixed distances from 1 to 400 m in three populations of wild barley. The self-pollinated and crossed progeny (F 1 ) and two generations of segregated progeny (F 2 and F 3 ) were tested in experimentally simulated population environments for relative performance (RP). The measured fitness traits included number of seeds, total seed weight and seed germination. For any of these traits, there was no association between RP of F 1 , F 2 and F 3 plants and either pairwise kinship coefficients or crossing distance. In contrast, in all three populations, we found lower seed viability of outcrossed as compared with self-pollinated genotypes in the first generation of segregation. However, in the F 3 generation this outbreeding effect disappeared in the two populations and greatly decreased in the third population. For seed production, heterosis in F 1 and outbreeding depression in F 2 were observed only in the population with unusually high number of heterozygotes. Our findings support the view that in selfing species a spatial mosaic of various locally abundant genotypes represents not randomly fixed combinations of alleles but the co-adapted gene complexes that were sieved by selection, while heterozygotes are characteristic for the transient phase of this process, when segregation and purging of maladaptive genotypes have not yet occurred.

Panax ginseng C.A. Meyer is an endangered species in Russia. To restore this species, effective protective measures, including the reintroduction into favorable habitats, must be worked out considering the specificity of genetic structure of ginseng populations. One hundred and thirtynine P. ginseng plants were collected from the forests of nine administrative areas of Primorsky Territory of Russia and transferred to a collection nursery for further investigation. Microsatellite markers were used to study the genetic diversity and the genetic structure of ginseng populations. For populations studied with SSR, the number of observed alleles was ranging from 15 to 25, allelic richness from 1.83 to 3.04, polymorphic loci from 62.5% to 87.7%, observed heterozygosity from 0.410 to 0.512 (an average of 0.453) and expected heterozygosity from 0.304 to 0.479, with an average of 0.393. The values of the inbreeding coefficient within populations (Fis) ranged from −0.447 to 0.056, and their average value was −0.296. Genetic differentiation among populations was significant (F st = 0.115) but an isolation-by-distance pattern was not detected. UPGMA and MStree confirmed the presence of genetic structure within P. ginseng and visualized genetic relationships of populations with similar pattern. STRUCTURE analysis revealed the genetic admixture between different ginseng populations. It was established with SSR markers that P. ginseng still preserves substantial genetic resources although all populations are largely exhausted. Because ginseng populations are significantly differentiated all of them should be restored. Considering the admixture of ginseng populations it would be advisable to apply the individual assignment test to verify the content of indigenous populations and to identify the "true" population plants to serve as stock material for reintroduction.

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