Prolonged culture of <Emphasis Type="Italic">Boesenbergia rotunda</Emphasis> cells reveals decreased growth and shoot regeneration capacity

We evaluated the ploidy levels and tissue culture responses of 16 Japanese Miscanthus accessions, which are registered and vegetatively maintained in the National Agriculture and Food Research Organization GeneBank, Japan, to screen suitable genotypes for the molecular breeding of Miscanthus species. A ploidy analysis showed that most M. sinensis and M. sinensis var. condensatus (var. condensatus) were putative diploids, but one accession identified as M. sinensis was unexpectedly a putative tetraploid. Additionally, M. sacchariflorus and its hybrid accessions were putative tetraploids. The deoxyribonucleic acid levels in var. condensatus were significantly higher than those in the diploid M. sinensis. Of the accessions, 10, including M. sinensis and var. condensatus, could induce plant regenerable embryogenic calli from apical meristems. We selected three of these M. sinensis accessions for further experiments because their calli growth rates were faster than those of the var. condensatus accessions. Tissue culture experiments with the selected accessions indicated that the frequencies of callus and green shoot formation strongly correlated with genotype. The broad-sense heritabilities of the embryogenic callus and green shoot formation frequencies in the selected accessions were 0.75 and 0.65, respectively, indicating that the cultures’ responses were mainly controlled by genetic factors. Thus, we further selected one accession that had the highest efficiencies in callus and green shoot formation, and we observed that light during callus culturing significantly inhibited calli growth, but promoted plant regeneration from calli in the selected accession.     

Factors influencing distribution and local coexistence of diploids and tetraploids of <Emphasis Type="Italic">Vicia cracca</Emphasis>: inferences from a common garden experiment

Vicia cracca diploids and autotetraploids are highly parapatric in Europe; tetraploids reside in western and northern part, whereas diploids occupy much drier south-eastern part. They meet together in a Central European contact zone. This distribution pattern raised questions about a transformative effect of polyploidization on plant performance and environmental tolerances. We investigated plant survival, growth, and seed production in two water regimes in a common garden experiment using seeds collected from five localities in the Central European contact zone where diploids and tetraploids occur in sympatry. Obtained data imply that tetraploids of V. cracca are not generally superior in performance to diploids. Significantly larger seeds from tetraploid mother plants collected in the field were not correlated with greater stature of the seedlings. Nonetheless, tetraploids might have a potential to out-compete diploids in the long run due to the tetraploids’ ability of greater growth which manifested in the second year of cultivation. Considering the response of diploids and tetraploids to water supply, drought stressed tetraploids but not diploids produced a higher proportion of aborted seeds than watered ones, which implies that tetraploids are more drought susceptible than diploids. On the other hand, decreased plant height in drought stresses tetraploids, which simultaneously increased total seed production, may suggest that tetraploids have a greater ability to avoid local extinction under unfavourable conditions by enhancing biomass allocation into production of seeds at the cost of lower growth. The significant interaction between ploidy level and locality in several traits suggests possible polyfyletic origin of tetraploids and the necessity to clarify the history of the tetraploids in Europe.     

Inferring the potential of plastid DNA-based identification of derived ferns: a case study on the <Emphasis Type="Italic">Asplenium trichomanes</Emphasis> aggregate in Europe

The utility of three plastid DNA regions to identify fern species was explored with focus on the European representatives of the Asplenium trichomanes aggregate. The sampling included representatives of the three diploid and the four tetraploid taxa recognized in the European flora plus Macaronesia. Besides European samples, the compiled data set comprised specimens of a putative Hawaiian endemic and one species occurring in Southeast Asia. By combining the sequences of three non-coding plastid regions, 13 haplotypes were recovered of which four were found in more than one taxon. Evidences for four distinct diploid lineages were found that correspond to Asplenium anceps, A. inexpectans, A. trichomanes s.s., and A. tripteropus. The four tetraploids occurring in Europe shared haplotypes with A. inexpectans. Thus, DNA barcoding can successfully identify the diploids, but fail to separate the tetraploids from their diploid ancestors. As a consequence, barcoding analyses of ferns need to take into account the differences of ploidy level measured by evidence independent from the DNA barcode. Evidence for uneven accumulation of intra-species DNA variation was recovered by comparing all species. Furthermore, the study provided evidence that the current taxonomy of these ferns requires to be revised. The two European diploids form well-separated clades and need to be recognized as A. inexpectans and A. trichomanes s.s. To keep name consistency for all European tetraploids, a new name Asplenium jessenii is introduced to replace A. trichomanes subsp. hastatum.     

FISH-aimed karyotype analysis in <Emphasis Type="Italic">Aconitum</Emphasis> subgen. <Emphasis Type="Italic">Aconitum</Emphasis> reveals excessive rDNA sites in tetraploid taxa

The location of 5S and 35S rDNA sequences in chromosomes of four Aconitum subsp. Aconitum species was analyzed after fluorescence in situ hybridization (FISH). Both in diploids (2n?=?2x?=?16; Aconitum variegatum, A. degenii) and tetraploids (2n?=?4×?=?32; A. firmum, A. plicatum), rDNA repeats were localized exclusively on the shorter arms of chromosomes, in subterminal or pericentromeric sites. All analyzed species showed similar basal genome size (Cx?=?5.31–5.71 pg). The most striking features of tetraploid karyotypes were the conservation of diploid rDNA loci and emergence of many additional 5S rDNA clusters. Chromosomal distribution of excessive ribosomal sites suggests their role in the secondary diploidization of tetraploid karyotypes.     

Promotion of shoot regeneration of <Emphasis Type="Italic">Swertia chirata</Emphasis> by biosynthesized silver nanoparticles and their involvement in ethylene interceptions and activation of antioxidant activity

A complete protocol for the in vitro induction of Eclipta alba tetraploids has been optimized to enhance the wedelolactone content, an anti-cancerous compound. The effects of different concentrations of colchicine (0, 0.01, 0.05, 0.1, 0.2 and 0.3%; w/v) along with treatment durations (12, 24, 36 and 48 h) were investigated on shoot tip (ST) and nodal segment (NS). The treated explants were then incubated on Murashige and Skoog (MS) medium having 1.5 mg L^?1 N⁶-benzylaminopurine and 0.5 mg L^?1 α-napthalene acetic acid for shoot regeneration and afterward root was induced on 1.0 mg L^?1 indole-3-acetic acid enriched ½MS medium. The tetraploids of E. alba were proficiently induced by the treatment of 0.1% colchicine for 24 h. The highest tetraploid induction efficiency was obtained from ST (30.56%) in comparison to the NS (22.22%). Analysis by spectrophotometry and flow cytometry showed that colchicine treated plants contained higher quantity of DNA than diploid plants. Cytological studies demonstrated doubled the chromosome number in tetraploids (2n?=?4x?=?44) than diploids (2n?=?2x?=?22). The ploidy level enhancement lead to alteration of other traits, like increased plant height, stem diameter, leaf size, stomatal size and chlorophyll content. As determined through high performance thin-layer chromatography, the ultimate achievement of this technique is the higher accumulation of wedelolactone in tetraploid plants (300.32 µg g^?1 dry weight) in evaluation to in vitro diploid (131.31 µg g^?1 dry weight) and in vivo diploid mother plants (93.26 µg g^?1 dry weight), thus improving the pharmaceutical value of E. alba.     

The role of triploids in the origin and evolution of polyploids of <Emphasis Type="Italic">Turnera sidoides</Emphasis> complex (Passifloraceae,Turneroideae)

Triploids can play an important role in polyploid evolution. However, their frequent sterility is an obstacle for the origin and establishment of neotetraploids. Here we analyzed the microsporogenesis of triploids (x?=?7) and the crossability among cytotypes of Turnera sidoides, aiming to test the impact of triploids on the origin and demographic establishment of tetraploids in natural populations. Triploids of T. sidoides exhibit irregular meiotic behavior. The high frequency of monovalents and of trivalents with non-convergent orientations results in unbalanced and/or non-viable male gametes. In spite of abnormalities in chromosome pairing and unbalanced chromosome segregation, triploids are not completely sterile and yielded up to 67% of viable pollen. Triploids that originated by the fusion of 2n?×?n gametes of the same taxon showed more regular meiotic behavior and higher fertility than triploids from the contact zone of diploids and tetraploids or triploids of hybrid origin. The reproductive isolation of T. sidoides cytotypes of different ploidy level is not strict and the ‘triploid block’ may be overcome occasionally. Triploids of T. sidoides produce diploid and triploid progeny suggesting that new generations of polyploids could originate from crosses between triploids or from backcrosses with diploids. The capability of T. sidoides to multiply asexually by rhizomes, would enhance the likelihood that a low frequency of neopolyploids can be originated and maintained in natural populations of T. sidoides.     

Methyl jasmonate regulated diploid and tetraploid black locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> L.) tolerance to salt stress

Methyl jasmonate (MeJA) is an essential and promising plant growth regulation factor that can improve plant development and growth. Here, we explored the mechanism by which MeJA regulates the tolerance of black locust (Robinia pseudoacacia L.) to salt stress. In this study, diploid and tetraploid R. pseudoacacia were subjected to three treatments: 500 mM NaCl; 100 μM MeJA; and 500 mM NaCl and 100 μM MeJA, and the changes in plant growth, endogenous MeJA levels and the anti-oxidative metabolism of leaves were investigated. The results showed that salt stress significantly inhibited plant growth and induced the accumulation of Na⁺ and Cl^? ions, malondialdehyde (MDA) content and reactive oxygen species. However, these adverse effects could be alleviated by applying MeJA, which was followed by a marked increase in the activities of antioxidant enzymes. In addition, some genes encoding several antioxidant enzymes were also up-regulated. Simultaneously, the endogenous MeJA content in MeJA-treated plants was lower than in salt-treated plants. It is noteworthy that tetraploids always possessed higher salt tolerance and obtained greater positive effects from MeJA than diploids. These results suggested that MeJA might play a protective role in defense responses, enabling diploid and tetraploid black locust, especially tetraploid, to better tolerate the adverse effects of salt stress.     

Serpentine ecotypic differentiation in a polyploid plant complex: shared tolerance to Mg and Ni stress among di- and tetraploid serpentine populations of <Emphasis Type="Italic">Knautia arvensis</Emphasis> (Dipsacaceae)

Background and aims

Serpentine soils impose limits on plant growth and survival and thus provide an ideal model for studying plant adaptation under environmental stress. Despite the increasing amount of data on serpentine ecotypic differentiation, no study has assessed the potential role of polyploidy. We tested for links between polyploidy and the response to serpentine stress in Knautia arvensis, a diploid-tetraploid, edaphically differentiated complex.

Methods

Variation in growth, biomass yield and tissue Mg and Ni accumulation in response to high Mg and Ni concentrations were experimentally tested using hydroponic cultivation of seedlings from eight populations of different ploidy and edaphic origin.

Results

Regardless of ploidy level, serpentine populations exhibited higher tolerance to both Mg and Ni stress than their non-serpentine counterparts, suggesting an adaptive character of these traits in K. arvensis. The effect of ploidy was rather weak and confined to a slightly better response of serpentine tetraploids to Mg stress and to higher biomass yields in tetraploids from both soil types.

Conclusions

The similar response of diploid and tetraploid serpentine populations to edaphic stress corresponded with their previously described genetic proximity. This suggests that serpentine tolerance might have been transmitted during the local autopolyploid origin of serpentine tetraploids.

     

The population genetics of the fundamental cytotype-shift in invasive <Emphasis Type="Italic">Centaurea stoebe</Emphasis> s.l.: genetic diversity,genetic differentiation and small-scale genetic structure differ between cytotypes but not between ranges

Polyploids are overrepresented in invasive species. Yet, the role of genetic diversity and drift in colonization success of polyploids remains unclear. Here, we investigate genetic diversity, genetic differentiation and small-scale genetic structure in our model system, the three geo-cytotypes of Centaurea stoebe: monocarpic diploids and polycarpic (allo)tetraploids coexist in the native range (Eurasia), but only tetraploids are reported from the invasive range (North America). For each geo-cytotype, we investigated 18–20 populations varying in size and habitat type (natural vs. ruderal). Population genetic analyses were conducted at eight microsatellite loci. Compared to diploids, tetraploids revealed higher genetic diversity and lower genetic differentiation, whereas both were comparable in tetraploids between both ranges. Within spatial distances of a few meters, diploid individuals were more strongly related to one another than tetraploids. In addition, expected heterozygosity in diploids increased with population size and was higher in natural than in ruderal habitats. However, neither relationship was found for tetraploids. The higher genetic diversity of tetraploid C. stoebe may have enhanced its colonization abilities, if genetic diversity is correlated with fitness and adaptive capabilities. Furthermore, the inheritance of a duplicated chromosome set as well as longevity and frequent gene flow reduces drift in tetraploids. This counteracts genetic depletion during initial introductions and in subsequent phases of small or fluctuating population sizes in ruderal habitats. Our findings advocate the importance of studying colonization genetic processes to gain a more mechanistic understanding of the role of polyploidy in invasion dynamics.     

Cytogenetic evidences on the evolutionary relationships between the tetraploids of the section <Emphasis Type="Italic">Rhizomatosae</Emphasis> and related diploid species (<Emphasis Type="Italic">Arachis</Emphasis>, Leguminosae)

Rhizomatosae is a taxonomic section of the South American genus Arachis, whose diagnostic character is the presence of rhizomes in all its species. This section is of particular evolutionary interest because it has three polyploid (A. pseudovillosa, A. nitida and A. glabrata, 2n?=?4x?=?40) and only one diploid (A. burkartii, 2n?=?2x?=?20) species. The phylogenetic relationships of these species as well as the polyploidy nature and the origin of the tetraploids are still controversial. The present study provides an exhaustive analysis of the karyotypes of all rhizomatous species and six closely related diploid species of the sections Erectoides and Procumbentes by cytogenetic mapping of DAPI/CMA heterochromatin bands and 5S and 18–26S rDNA loci. Chromosome banding showed variation in the DAPI heterochromatin distribution pattern, which, together with the number and distribution of rDNA loci, allowed the characterization of all species studied here. The bulk of chromosomal markers suggest that the three rhizomatous tetraploid species constitute a natural group and may have at least one common diploid ancestor. The cytogenetic data of the diploid species analyzed evidenced that the only rhizomatous diploid species—A. burkartii—has a karyotype pattern different from those of the rhizomatous tetraploids, showing that it is not likely the genome donor of the tetraploids and the non-monophyletic nature of the section Rhizomatosae. Thus, the tetraploid species should be excluded from the R genome, which should remain exclusively for A. burkartii. Instead, the karyotype features of these tetraploids are compatible with those of different species of the sections Erectoides and Procumbentes (E genome species), suggesting the hypothesis of multiple origins of these tetraploids. In addition, the polyploid nature and the group of diploid species closer to the tetraploids are discussed.     

Genome size and ploidy level among wild and cultivated <Emphasis Type="Italic">Prunus</Emphasis> taxa in Slovakia

2C DNA content and ploidy level variation of Prunus spinosa and closely related taxa together with Prunus domestica L. and Prunus insititia L. was studied in Slovakia. The aim of the study was to define genome sizes and find differences between closely related taxa within Prunus spinosa sensu lato mentioned in previous works. According to our results, investigated taxa can be divided into three groups according to ploidy level: Prunus spinosa, Prunus dasyphylla, Prunus ×fruticans, Prunus ×dominii and Prunus ×schurii are tetraploids, Prunus ×fechtneri is pentaploid, and P. domestica and P. insititia are hexaploids. Genome size differences within tetraploid taxa were relatively small (Prunus spinosa: 1.40?±?0.02, P. ×domini: 1.44?±?0.01, P. ×fruticans: 1.48?±?0.02, P. ×schurii: 1.44?±?0.02), but statistically significant. Although further research is needed, it seems that the concept of several taxa as product of hybridization between P. spinosa and cultivated plum species has been supported by our study.     

Hybridization success is largely limited to homoploid <Emphasis Type="Italic">Prunus</Emphasis> hybrids: a multidisciplinary approach

Prunus fruticosa is a rare shrub occurring in Eurasian thermophilous forest-steppe alliances. The species frequently hybridizes with cultivated Prunus species in Europe (allochthonous tetraploid P. cerasus and partly indigenous diploid P. avium). Propidium iodide flow cytometry, distance-based morphometrics, elliptic Fourier analysis and embryology were employed to evaluate the extent of hybridization in six Slovak populations. Flow cytometric analyses revealed three ploidy levels: diploid (P. avium), triploid (P. × mohacsyana) and tetraploid (P. fruticosa, P. × eminens and P. cerasus). In addition, P. fruticosa and P. cerasus, at the tetraploid level, were found to differ in absolute genome size. An embryological evaluation suggested the existence of a triploid block in P. × mohacsyana and significant potential for hybridization among tetraploid taxa (indicated also by a continuous distribution of genome size data and further mirrored by morphometrics). Although hybrids significantly differ in ploidy level and embryological characteristics, they are almost indistinguishable using morphological characters. Hybridization with P. cerasus thus turns out to be a significant threat to wild populations of P. fruticosa compared to the relatively weak influence of P. avium.     

Differentiation of the pollen size in five representatives of <Emphasis Type="Italic">Taraxacum</Emphasis> sect. <Emphasis Type="Italic">Palustria</Emphasis>

Measurements of the pollen size in 5 species of Taraxacum sect. Palustria at three levels of ploidy: 2n = 3x = 24 (T. paucilobum), 2n = 4x = 32 (T. vindobonense, T. trilobifolium), 2n = 5x = 40 (T. mendax) and one taxon of unknown number of chromosomes 2n = ? (T. portentosum) are presented in this paper. Obtained results indicate a lack of distinct positive correlation between the pollen size and ploidy in the studied group of plants. Distinct relationship was, however, found between ploidy and the range of pollen size and shape variability. Most variable were the pollen grains of triploid T. paucilobum and the least — those in pentaploid T. mendax. Ranges of pollen variability in tetraploid T. trilobifolium and T. vindobonense and in T. portentosum of unknown number of chromosomes showed intermediate values.     

The systematics of autopolyploidy in Epilobium latifolium (Onagraceae)

Diploid (2n = 36) plants ofEpilobium latifolium L. have been found in Alaska and the western Cordillera of North America, and tetraploids in Iceland, western Greenland, and southeastern Quebec. Study of the morphology of these chromosome races revealed a character, the number of pores in the pollen grains, by which they could be distinguished with an average probability of 75%. Tetraploids ofE. latifolium tend to have high percentages of 4-pored pollen, while the diploids usually have only 3-pored pollen. On this basis, the ranges of the races were extrapolated from herbarium material. Detailed comparisons of eight other features of the presumptive diploids and tetraploids showed no significant difference between them. The races appear to form worldwide, allopatric, ecogeographic phases. A high level (57.4%) of quadrivalent formation observed during tetraploid meiosis, and other considerations, indicate that the tetraploids arose by autopolyploidy. The recommendation is made that the races not be given formal taxonomic recognition.     

Integrated taxonomy of the <Emphasis Type="Italic">Asplenium normale</Emphasis> complex (Aspleniaceae) in China and adjacent areas

The Asplenium normale D. Don complex comprises several taxa that are either diploid or tetraploid. The tetraploids are assumed to have originated from diploid ancestors by relatively recent autopolyploidization or allopolyploidization. Some of the diploids are readily recognized morphologically but most of the taxa have until now been placed into a single species. However, phylogenetic studies have challenged this treatment and emphasized the notion that the taxonomic treatment of this complex needs to be revised. An integrative taxonomic approach was employed to delimit species in the complex using cytological, morphological, and DNA sequence data. Initially, we employed a diploid first approach to establish a robust taxonomic framework. Special efforts were made to collect and identify the diploid progenitors of each polyploid lineage identified in the plastid DNA based phylogenetic hypothesis. A total of six distinct diploid species were identified. The distinctive nature of the six diploids is strongly supported by sequence differences in plastid DNA and nuclear loci, as well as by the results of morphometric analysis. Diagnostic morphological characters were identified to distinguish the six diploid species, resulting in their revised taxonomy, which includes two novel species, namely, Asplenium normaloides and A. guangdongense. Further studies to strengthen the taxonomic classification of all of the tetraploid taxa are warranted.     

Karyo-taxonomic study of the genus<Emphasis Type="Italic">Pseudolysimachion</Emphasis> (<Emphasis Type="Italic">Scrophulariaceae</Emphasis>) in the Czech Republic and Slovakia

Flow cytometry was used to determine ploidy levels in the Czech and Slovak taxa of the genusPseudolysimachion (W.D.J. Koch)Opiz (=Veronica auct. p.p.,Scrophulariaceae). In total, 123 populations from the Czech Republic, Slovakia, Ukraine (one locality), Austria (one locality) and Hungary (one locality) were analyzed. InP. maritimum (L.)Á. Löve etD. Löve andP. spicatum (L.)Opiz, two cytotypes were found: diploid (2n=2x=34) and tetraploid (2n=4x=68). In both species the tetraploid cytotype predominated (P. maritimum: 41 tetraploid populations out of 45;P. spicatum: 57 tetraploid populations out of 58). The two cytotypes ofP. maritimum have no taxonomic significance because ploidy level is not obviously correlated with morphology, distribution pattern or ecology. Tetraploid populations ofP. spicatum belong to two morphologically different subspecies, subsp.spicatum and subsp.fischeri Trávní?ek. The diploid cytotype (one population only) should be provisionally classified as a third subspecies ofP. spicatum, which is morphologically similar to the Asian subsp.porphyrianum (Pavlov)Trávní?ek. Only diploid plants (2n=2x=34) ofP. orchideum (Crantz)Wraber were found; all 13 populations that were analyzed belong toP. orchideum s.str. One diploid population sample ofP. spurium subsp.foliosum (Waldst. etKit.)Holub (2n=2x=34) and one tetraploid sample ofP. incanum subsp.pallens (Host)Trávní?ek (2n=4x=68) were also analyzed. In addition, three tetraploid populations of hybrid origin were investigated:P. maritimum ×P. spicatum subsp.spicatum (one population) andP. maritimum ×P. spurium subsp.foliosum (two populations). While hybrid plants ofP. maritimum ×P. spicatum arose from tetraploid parental species, plants ofP. maritimum ×P. spurium probably resulted from a cross between tetraploidP. maritimum and diploidP. spurium. The putative origin and evolutionary importance of polyploids in thePseudolysimachion are discussed.     

Early characterization of somatic hybrids from symmetric protoplast electrofusion of <Emphasis Type="Italic">Solanum pinnatisectum</Emphasis> Dun. and <Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.

Variability of 31 somatic hybrids of Solanum pinnatisectum Dun. with Solanum tuberosum L. for leaf morphology, plant vigor, resistance to Phytophthora infestans, ploidy level, and cytoplasm type was evaluated in vitro. The composition of these somatic hybrids was as follows: [S. pinnatisectum Dun. (2n = 2x = 24; cytoplasmic type Wγ) + S. tuberosum L. (2n = 4x = 48; cytoplasmic type Tß)]. Based on leaf morphology and plant growth vigor, plants were divided into three groups, including plants close to tbr parent with unlobed leaves, small plants with scarcely dissected leaves, and vigorous plants with asymmetrically and pinnately lobed leaves. Nine of the somatic hybrids were found to be highly resistant to P. infestans. Somatic hybrids were either tetraploid or hexaploid, with hexaploids being predominant. The cytoplasm of somatic hybrids was either Tßγ or Wßγ, with Tßγ being more common. Overall, in contrast to leaf morphology and growth vigor, level of resistance to P. infestans was not related to either ploidy level or type of cytoplasm. These findings demonstrate that early in vitro selection of promising hybrids can be useful in breeding programs.     

Correction to: Shoot regeneration process and optimization of <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation in <Emphasis Type="Italic">Sinningia speciosa</Emphasis>

The objective of this research was to induce mitotic chromosome doubling in Anemone sylvestris L. The mitosis inhibitor oryzalin was directly added to the induction medium at 1, 2, 5, 10 and 15 μM for 8, 10 or 12 weeks of cultivation. Three tetraploid plants (2n?=?4x?=?32), 0.8% (polyploidization efficiency), were obtained from diploid plants (2n?=?2x?=?16) in three treatments (1 μM for 10 weeks, 5 μM for 8 weeks and 8 μM for 10 weeks). Ploidy level was confirmed by flow cytometry. Morphological characteristics (e.g. flower diameter, total plant height, leaf area) and chlorophyll content differences between diploid and tetraploid A. sylvestris were observed together with polyphenol content and antioxidant activity. The inter primer binding sites markers were used for evaluation of polymorphism. New genotypes with different morphological and biological characteristics were obtained through somatic polyploidization. The tetraploid plants were stronger, more vigorous and had an early flowering, which is essential for its use as an ornamental plant. The iPBS analysis showed unique amplicons that can be used for the purposes of molecular identification of tetraploid plants of A. sylvestris in the future. The results demonstrate the first report of in vitro induction of tetraploids of A. sylvestris.     

Genetic differentiation in the polyploid complex of <Emphasis Type="Italic">Suaeda corniculata</Emphasis> (C.A. Mey.) Bunge in Eastern Siberia

Data on differentiation of the polyploid complex of Suaeda corniculata (C.A. Mey.) Bunge in East Siberia based on variability of morphological characteristics, karyological analysis, and genetic polymorphism in inter simple sequence repeat (ISSR) markers were given for the first time. It was established that the samples studied belonged to three cytotypes: diploids (2n = 2x = 18), tetraploids (2n = 4x = 36) and hexaploids (2n = 6x = 54). The analysis of variability of morphological characteristics by the method of principal coordinates showed division of the samples into three separate groups. On the basis of morphological and molecular-genetic methods, a genetically differentiated diploid population was revealed in Yakutia.     

Meiotic chromosome configurations in oocytes of <Emphasis Type="Italic">Cobitis taenia</Emphasis> and its polyploid hybrids

Diploid and triploid hybrid females of Cobitis as a rule produce unreduced eggs which mainly develop gynogenetically, but some of the eggs incorporate sperm genome and develop into triploids and tetraploids, respectively. Here, we observed for the first time the meiotic chromosomes in the germinal vesicles (GVs) of mature oocytes of three diploid C. taenia (2n = 48) and 20 allopolyploid females of Cobitis (18 triploid 3n = 74 and 2 tetraploid 4n = 99). The majority of GVs in diploid, triploid and tetraploid females contained 24, 74 and 96 or 99 bivalents, respectively. These results directly indicated premeiotic endomitosis as a mechanism underlying the formation of unreduced eggs in allopolyploid females of Cobitis.