O. G. Koren

The Agrobacterium rhizogenes rolC-gene-induced somatic embryogenesis and shoot organogenesis in Panax ginseng transformed calluses

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.

RAPD and Allozyme Analysis of Genetic Diversity in Panax ginseng C.A. Meyer and P. quinquefolius L.

Inter- and intraspecific variation of two ginseng species Panax ginseng and P. quinquefolius was estimated by studying 159 RAPD and 39 allozyme loci. Parameters of polymorphism and genetic diversity were determined and a tree was constructed to characterize the differences between individual plants, samples, and species. Genetic variation in P. ginseng proved to be lower than in P. quinquefolius. Gene diversity in the total P. ginseng sample was comparable with the mean expected heterozygosity of herbaceous plants. This suggests that wild P. ginseng plants in various areas of the currently fragmented natural habitat and cultivated plants of different origin have retained a significant proportion of their gene pool. The mean heterozygosity calculated per polymorphic locus for the RAPD phenotypes is similar to that of the allozyme loci and may be helpful in estimating gene diversity in populations of rare and endangered plant species.

High Polymorphism and Autotetraploid Origin of the Rare Endemic SpeciesOxytropis chankaensisJurtz. (Fabaceae) Inferred from Allozyme Data

Using starch electrophoresis, we examined 19 enzyme systems presumably controlled by 35 loci in the rare endemic tetraploid speciesOxytropis chankaensisJurtz. (Fabaceae). Electrophoretic patterns and their genetic interpretation are presented. The isozyme data suggest tetrasomic inheritance in O. chankaensis. Three or four alleles at a particular locus were found in a number of individual plants, which indicate the autotetraploid origin of this species. Seventeen loci were shown to be polymorphic. As reliable gene markers for population systems, we recommend highly active polymorphic systems showing good allozyme separation (Ce-2, Gpi-2, Gpt-2, Idh-2, Lap, Mdh-2, and Mdh-3). Parameters of allozyme variability proved to be very high for a rare species with a restricted range: P = 48.6%, A = 2, Ap = 3.06, Hob = 0.173.

Specific features of pollination in the Manchurian birthwort, Aristolochia manshuriensis

An analysis of pollination system in Aristolochia manshuriensis has shown that flower structure in this species is strictly adapted to cross-pollination, but the possibility of an autogamous or geitonogamous type of self-pollination with the involvement of insects is not excluded. The flowers of A. manshuriensis are most frequently visited by flies of the family Anthomyiidae, which markedly contribute to their pollination. Males account for 65% of pollinator insects collected from the flowers.

Genetic structure and differentiation of populations of the tetraploid species Oxytropis chankaensis (Fabaceae)

The population genetic variation of the tetraploid species Oxytropis chankaensis Jurtz. (Fabaceae), a local endemic of the western coast of Khanka Lake (Primorye), was examined. Five populations were analyzed using 28 isozyme loci encoding 16 enzyme systems. Significant allelic heterogeneity among the populations was found for six out of twelve polymorphic loci. The heterozygosity of the samples (total sample size 294 plants) He = 0.301 was considerable higher than the mean values in populations of endemic species (0.076). Based on the results of this study, we identified two groups of O. chankaensis populations (southern and northern), in spite of the absence of marked hiatus between them. Of special interest is the population from Przhewalski Spit, which is a natural reserve of genetic diversity of the species and the putative center of formation of the autotetraploid O. chankaensis.

Allozyme Variation of the Relict Plant Aristolochia manshuriensis Kom. (Aristolochiaceae)

Allozyme variation of a rare relict plant, birthwort Aristolochia manshuriensis Kom., was examined. The main parameters of genetic variation in natural populations of A. manshuriensis from the Anan’evka, Nezhinka, and Malaya Borisovka river basins (Primorskii Krai) were inferred from analysis of nine enzyme systems, presumably encoded by 18 loci. At 99% polymorphism criterion, 24.4% of A. manshuriensis loci were shown to be polymorphic. The mean number of alleles per locus was 1.24; the mean observed and expected heterozygosities, 0.12 and 0.10, respectively.

Genetic variation of Oplopanax elatus (Nakai) Nakai (Araliaceae)

Using allozyme analysis, genetic and genotypic variation of rare relict species, a member of one of ancient angiosperm families, Araliaceae, the clonal plant Oplopanax elatus (Nakai) Nakai, was evaluated. Electrophoretic separation of the enzymes is described, and genetic interpretation of the enzymes variation patterns is presented. The values of genetic variation indices obtained were low (P = 25%; A = 1.45: Ho = 0.131; He = 0.113) and comparable with the data reported for the rare plant species and the representatives of the family Araliaceae. The main factors responsible for the polymorphism level observed might be the evolutionary history of the species and gene drift. The level of genotypic diversity (G/N = 0.76; D = 0.97) was substantially higher, compared to the values reported for species with vegetative reproduction (D = 0.62). These results suggest certain contribution of the propagation by seeds in the formation of the species of interest.

Genetic structure of natural populations of the relict species Aristolochia manshuriensis (Aristolochiaceae) in disturbed and intact habitats

Genetic structure of natural populations of the rare relict plant Manchurian birthwort (Aristolochia manshuriensis Kom.) in the Russian part of its area was analyzed using allozyme markers. The studied A. manshuriensis populations differed in the degree of their intrapopulation differentiation. The populations Nezhinka and Anan’evka were more differentiated (FST = 0.1209 and 0.0576, respectively); these populations are located close in the regions of intense economic activity and are exposed to the strongest anthropogenic impact. A low degree of differentiation was detected in the population Malaya Borisovka (FST = 0.0393), localized to intact habitats. The overall heterogeneity test has demonstrated that the population Malaya Anan’evka, exposed at present to small anthropogenic stress yet growing in disturbed habitats, displays no differentiation. These results suggest that at least three populations are influenced by genetic drift connected with a decrease in the reproductive and effective population sizes, which is caused, in particular, by anthropogenic impact. A high level of genetic similarity between the A. manshuriensis populations in Primor’e is discussed in connection with the evolutionary history of this species.

Genetic variation and differentiation in populations of Japanese emperor oak Quercus dentata Thunb. and Mongolian oak Quercus mongolica Fisch. ex Ledeb.) in the south of the Russian Far East

Allozyme variation of Japanese emperor oak Quercus dentata Thunb. and Mongolian oak Quercus mongolica Fisch. ex Ledeb.) was examined in 11 populations of these species from southern Primorye. Analysis of 18 loci showed that in these populations, 66.7% of genes of Mongolian oak are polymorphic, the number of alleles per locus being 2.28. In Japanese emperor oak, these parameters were respectively 59.8 and 2.36%. The observed heterozygosity in both species did not differ from the expected values, constituting 0.198 in Japanese emperor oak and 0.161 in Mongolian oak. The Nei’s distance between Quercus mongolica and Q. dentata was 0.053. The main contribution to the species differentiation is made by loci Lap-1, Idh-1, Pgm-1, and Ndh-1, although none of them is diagnostic. The Japanese emperor oak and Mongolian oak populations formed separate clusters in an UPGMA dendrogram. Taking into account morphological and ecological isolation of the species, we suggest that the differences in gene frequencies may reflect selection acting in favor of adaptation to different growth conditions and counteracting between-species hybridization.

Genetic diversity of a rare species Aristolochia contorta Bunge (Aristolochiaceae) in Primorsky Krai

The herbaceous vine, twisted birthwort Aristolochia contorta Bunge, is a rare species listed in the Red Data Book of Primorsky krai (2008). On the northern boundary of its range (south of the Russian Far East), the species is represented by small isolated populations confined to the river drainages. Using allozyme analysis, genetic variation of nine natural populations of A. contorta (247 accessions), which represented the main part of the species range in Russia, was examined. The values of genetic variation indices (P = 22.7%; A = 1.28; Ho = 0.129; He = 0.101) were low and comparable with the data obtained for other rare plants. The proportion of unique genotypes (G/N) and Simpson’s genotypic diversity index (D) ranged from 0.32 to 0.64 and from 0.60 to 0.98, respectively. This means that A. contorta is characterized by sexual and asexual reproduction. Moreover, the ratio between these types of reproduction varied among the populations. Complete absence of inbreeding and excess of heterozygotes (FIS = −0.282), which was low probable in case of free mating, was observed. Evidently, clonal growth and (or) apomixis enables the species to maintain certain level of heterozygosity despite of small population sizes and non-regular gene exchange.