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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

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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To find more morphological characteristics useful for discussion on aralian or non-aralian Panax affinity, pollen morphological diversity was comparatively analysed in P. ginseng, Aralia elata and Oplopanax elatus collected during their pollination periods. In the anthers of both the buds and open flowers, the pollen average diameter varied between some species-specific maximum and minimal measurement. However, the larger pollen grains were typically found in the buds whereas the smaller pollen prevailed in the open flowers, testifying to the pollen size diminution during anther maturation. Based on this finding, the subsequent examination of pollen according to size decrease was put into operation as a method of pollen modification for the study. The structural mechanisms of pollen metamorphosis were identified as not being species specific but rather universal. These mechanisms are suggested to be the shrinkage of the pollen vegetative cytoplasm, the intine enlargement, the deepening of three colporate apertures provided by exine sunken into enlarged intine areas, the aperture accretion as well as the transformation of the exine from thick/sculptured into thin/less sculptured. During 'size-reducing metamorphosis', the pollen grains changed dramatically, going through a species-specific set of intermediate morphs to the final species-specific morphotype. In P. ginseng this morphotype is round (diameter is about 16 microm), in A. elata it is round with a single projection (diameter is about 15 microm) and in O. elatus it is ovoid with a single projection (average diameter is about 18 microm). In addition, every species is peculiar in having the unique vegetative cytoplasm inclusions and individual construction of the largest pollen exine. From a phylogenetic perspective, these findings presumably add support to the option of equal remoteness of P. ginseng from A. elata and O. elatus. The characteristics found seem to be suitable for examination of Panax affinity, by the subsequent study of more Araliaceae representatives.