Pentaploid Species Research Articles

Biological Properties of Recently Described Wild Bramble Rubus oklejewiczii against the Species from Similar Niches.

The aim of this study was to compare the biological properties, such as antiviral, antibacterial, and antioxidant, of recently described pentaploid species Rubus oklejewiczii with tetraploid taxa growing in similar habitats including R. plicatus, R. gracilis, and R. wimmerianus. The antiviral potential was analyzed against bacteriophages with different genetic material: phi6 (a surrogate for the SARS-CoV-2 virus), T7, phiX174, and MS2. Antibacterial properties of fruit and leaf extracts were determined against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Salmonella enterica. The total phenolic content, as well as anthocyanins, ascorbic acid, pH, and antioxidant properties (FRAP and DPPH) were determined. R. oklejewiczii leaf extract was characterized by the weakest antibacterial and antiviral properties, which was closely correlated with the lowest content of polyphenolic compounds and antioxidant properties. The strongest biological properties were observed for R. wimmerianus leaves. Fruit extracts were characterized by lower phenolic content and antioxidant activities than leaves, with the lowest values observed for R. oklejewiczii extract. The antibacterial properties of fruit extracts were strongest for R. gracilis. The strongest antiviral potential was observed for R. oklejewiczii and R. wimmerianus fruit extracts against the bacteriophage phi6, which correlated with the lowest pH and the highest ascorbic acid content. The positive effect of the higher ploidy of R. oklejewiczii for most of the analyzed biological properties was not observed except for the antiviral potential of fruit extract. Due to its large and tasty fruits, this species seems to be very promising for cultivation and attractive for consumers, even though most of its biological properties were not any better compared to other examined tetraploid species.

Epigenetic histone H3 phosphorylation marks discriminate between univalent- and bivalent-forming chromosomes during canina asymmetrical meiosis.

Dogroses (Rosa sect. Caninae) are mostly pentaploid, bearing 2n = 5x = 35 chromosomes in somatic cells. They evolved a unique form of asymmetrical meiosis characterized by two types of chromosomes: (1) chromosomes forming bivalents and distributed in the normal sexual way; and (2) chromosomes occurring as univalents and transferred by a female gamete only. In the mature pollen of pentaploid species, seven bivalent-derived chromosomes are transmitted to offspring, and 21 unpaired univalent chromosomes are eliminated during microsporogenesis. To discriminate between bivalent- and univalent-forming chromosomes, we studied histone H3 phosphorylation patterns regulating meiotic chromosome condensation and segregation. We analysed histone modification patterns during male canina meiosis in two representative dogrose species, 5x Rosa canina and 5x Rosa rubiginosa, by immunohistochemical and molecular cytogenetics approaches. Immunostaining of meiotic cells included α-tubulin, histone H3 phosphorylation (H3S10p, H3S28p and H3T3p) and methylation (H3K4me3 and H3K27me3) marks. In addition, fluorescent in situ hybridization was carried out with an 18S rDNA probe. In the first meiotic division, univalent chromosomes underwent equational division into chromatids, while homologues in bivalents were segregated as regular dyads. In diakinesis, bivalent chromosomes displayed strong H3 phosphorylation signals in proximal regions, spreading to the rest of the chromosome. In contrast, in univalents, the H3 phosphorylation signals were weaker, occurring mostly outside proximal regions largely overlapping with the H3K4me3 signals. Reduced phosphorylation was associated with relative under-condensation of the univalent chromosomes, particularly at early diakinesis. We hypothesize that the absence of pairing and/or recombination in univalent chromosomes negatively affects the histone H3 phosphorylation of their chromatin and perhaps the loading of meiotic-specific cohesins. This apparently destabilizes cohesion of sister chromatids, leading to their premature split in the first meiotic division.

Taxonomy and distribution of the genus Santolina (Asteraceae) in Italy

The Santolina chamaecyparissus complex includes 13 species of dwarf aromatic evergreen shrubs from the western Mediterranean Basin. Five native species occurring in Italy are currently accepted. Four of them are endemic to relatively restricted areas in the peninsula, whereas S. corsica Jord. & Fourr. is endemic to Corsica and Sardinia. The taxonomic treatments of Italian Santolina have been changing significantly in the past, probably due to the misinterpretation of naturalised populations of S. chamaecyparissus, a widely cultivated pentaploid species, which occasionally escapes from cultivation through agamospermy or vegetative propagation. In this study, we carried out the first quantitative morphometric and comparative niche analyses concerning the four species endemic to continental Italy (S. etrusca, S. ligustica, S. neapolitana, and S. pinnata). Morphometric analyses (PCoA, Random Forest, and univariate analyses) show that these species can be easily distinguished by combinations of character states, whereas niche analyses (Schoener’s D and similarity test) suggest that they occur in distinct climatic conditions. Based on our results, we fully confirm the taxonomic distinctiveness of these species. An updated identification key, including all Santolina species occurring in Italy, is presented.&nbsp

Chromosome measurements of wild roses of Iran

The genus Rosa is made up of four subgenera, of which the subgenus Rosa (= Eurosa) contains about 95% of all species, and is subdivided into 10 sections. In Iran, there are 15 rose species. In the present investigation, chromosome characteristics of 14 Iranian rose species were studied: Rosa persica, Rosa hemisphaerica, Rosa foetida, Rosa pimpinellifolia, Rosa beggeriana, Rosa boissieri, Rosa iberica, Rosa orientalis, Rosa elimatica, Rosa canina, Rosa pulverulenta, Rosa villosa, Rosa moschata and Rosa × damascena. Chromosome characteristics were measured using image analyzer MicroMeasure 3.3. Genome size and ploidy level of the roses were determined using a flow cytometer. The results of the flow cytometry analysis revealed that the genome size of diploid species was from 0.83 to 1.21 pg, and their genome size by karyotyping measurements was between 46.36 and 56.63 μm. In tetraploids, the genome size was between 1.91 and 2.29 pg and between 86.55 and 106.31 μm by flow cytometry and karyotype analysis, respectively. In the pentaploid species, genome sizes were 2.69 to 3.09 pg and 90.35 to 140.96 μm calculated by flow cytometry and karyotyping analysis, respectively. In hexaploid rose, flow cytometry and karyotyping analysis showed that the genome sizes were 3.54 pg and 147.84 μm, respectively. R. moschata (2n=2x=14) had the longest total chromosome length of the monoploid set (28.32 μm) and average length of one chromosome (4.04 μm). R. orientalis (2n=5x=35) had the longest average length of the small arm (1.76 μm) and big arm (2.28 μm). The maximum average ratio of length of big arm to the length of small arm (1.39) was in R. × damascena (2n=4x=28). The results of this study could be used in future rose breeding and in taxonomic and evolutionary studies of Iranian rose species.

Frequent silencing of rDNA loci on the univalent-forming genomes contrasts with their stable expression on the bivalent-forming genomes in polyploid dogroses (Rosa sect. Caninae)

The polyploid species in Rosa section Caninae (2n=21, 28 or 35) are characterized by an unusual reproductive system known as odd (or asymmetric) meiosis. Only two chromosome sets form bivalents in meiosis, whereas the remaining chromosomes are transmitted as univalents through the female germline. Evolution of ribosomal rRNA genes (rDNA) does not seem to be significantly affected by interlocus homogenization in dogroses. As a consequence, most species contain several rDNA families falling into two main clades (beta and gamma) thought to be differentially distributed between bivalent and univalent chromosomes, respectively. Here, we have investigated expression of rRNA gene families in five pentaploid species (R. canina, R. rubiginosa, R. dumalis, R. sherardii and R. caesia, 2n=35) and in one tetraploid (R. mollis, 2n=28). Using extensive sequencing of ITS clones and cleaved amplified polymorphism sequence (CAPS) analysis, we found that the beta-family was constitutively expressed in all species. However, there was large variation in the expression patterns of families constituting the gamma-clade. In addition, a single family can be active in one species, whereas silenced in another. The data show that the families on bivalent-forming chromosomes dominate rDNA expression in all dogrose species. We hypothesize that genes on bivalent genomes are stably expressed, whereas those on univalent genomes undergo variable levels of epigenetic silencing. Nonetheless, mosaic expression of univalent genomes could contribute to phenotypic variation between the species.

Microsatellite DNA marker inheritance indicates preferential pairing between two highly homologous genomes in polyploid and hemisexual dog-roses, Rosa L. Sect. Caninae DC.

According to previous cytological evidence, the hemisexual dog-rose species, Rosa sect. Caninae, transmit only seven chromosomes (derived from seven bivalents) through their pollen grains, whereas egg cells contain 21, 28 or 35 chromosomes (derived from seven bivalents and 14, 21 or 28 univalents) depending on ploidy level. Two sets of reciprocal pairwise interspecific crosses involving the pentaploid species pair R. dumalis and R. rubiginosa, and the pentaploid/tetraploid species pair R. sherardii and R. villosa, were analysed for 13 and 12 microsatellite DNA loci, respectively. Single loci were represented by a maximum of three simultaneously occurring alleles in R. villosa, and four alleles in the other three parental plants. In the experimentally derived offspring, the theoretical maximum of five alleles was found for only one locus in the pentaploid progenies. Microsatellite DNA allele composition was identical with that of the maternal parent in 10 offspring plants, which were probably derived through apomixis. Almost all microsatellite DNA alleles were shared with the maternal parent also in the remaining offspring, but 1-4 alleles shared only with the paternal parent, indicating sexual seed formation. Analysis of quantitative peak differences allowed a tentative estimation of allelic configuration in the individual plants, and suggested that bivalent formation preferentially takes place between chromosomes that consistently share the same microsatellite alleles and therefore appear to be highly homologous. Moreover, alleles that were shared between the species in each cross combination comparatively often appear to reside on the bivalent-forming chromosomes, whereas species-specific alleles instead occur comparatively often on the univalent-forming chromosomes and are therefore inherited through the maternal parent only. Recombination then takes place between very similar genomes also in interspecific crosses, resulting in a reproduction system that is essentially a mixture between apomixis and selfing.

Cross- and self-compatibility in various species of the genus Rosa

SummarySelf- and cross-compatibility was evaluated under field conditions in 48 taxa belonging to all sections of subgenus Rosa and subgenus Platyrhodon in the genus Rosa. Four species exhibited fruit set through self-pollination out of the 28 diploid species tested. In contrast, nine out of 12 tetraploid species, all of pentaploid species, and four out of five hexaploid species exhibited fruit set through self-pollination. Thus, it may be generally said that the self-incompatibility in the genus Rosa breaks down with polyploidization. The relationship between self-incompatibility and ploidy level is discussed.

Differences in the rust resistance of greenhouse and outdoor‐grown white birch species, Betula spp.

SummaryThe 2‐year‐old seedlings of five different white birch species (Betula platyphylla, Betula papyrifera, Betula pubescens, Betula pendula (two types) and Betula resinifera x Betula pendula) grown both in a greenhouse and outdoors, were inoculated in a leaf disc assay with two different birch rust (Mel‐ampsoridium betulinum) isolates from B. pendula and B. pubescens. The resistance of these birch species varied significantly. Resistance to the B. pubescens rust isolate was not related to the resistance of the B. pendula rust isolate. The behaviour of a birch genotype grown in the greenhouse did not correspond to the behaviour of the same genotype grown outdoors.The outdoor growth environment greatly increased the contents of soluble proteins, rubisco, chloro‐phyll and nitrogen in the leaves of diploid birch species (B. platyphylla, B. pendula and B. resinifera x B. pendula). For tetraploid and pentaploid species (B. pubescens and B. papyrifera, respectively) there was no such clear difference in the leaf physiological status between the seedlings grown outdoors and in the greenhouse. The C:N ratio was higher for the greenhouse‐grown seedlings in all the birch species, but the difference was significant only with the diploid species. The incidence of rust in the birch species did not correlate with any of the leaf physiological parameters studied. The adaptability of birch genotypes to the environment in relation to their resistance to birch leaf rust is discussed.

Cytophotometric and biochemical analyses of DNA in pentaploid and diploid Agave species

Nuclear DNA content, chromatin structure, and DNA composition were investigated in four Agave species: two diploid, Agave tequilana Weber and Agave angustifolia Haworth var. marginata Hort., and two pentaploid, Agave fourcroydes Lemaire and Agave sisalana Perrine. It was determined that the genome size of pentaploid species is nearly 2.5 times that of diploid ones. Cytophotometric analyses of chromatin structure were performed following Feulgen or DAPI staining to determine optical density profiles of interphase nuclei. Pentaploid species showed higher frequencies of condensed chromatin (heterochromatin) than diploid species. On the other hand, a lower frequency of A-T rich (DAPI stained) heterochromatin was found in pentaploid species than in diploid ones, indicating that heterochromatin in pentaploid species is made up of sequences with base compositions different from those of diploid species. Since thermal denaturation profiles of extracted DNA showed minor variations in the base composition of the genomes of the four species, it is supposed that, in pentaploid species, the large heterochromatin content is not due to an overrepresentation of G-C repetitive sequences but rather to the condensation of nonrepetitive sequences, such as, for example, redundant gene copies switched off in the polyploid complement. It is suggested that speciation in the genus Agave occurs through point mutations and minor DNA rearrangements, as is also indicated by the relative stability of the karyotype of this genus. Key words : Agave, DNA cytophotometry, DNA melting profiles, chromatin structure, genome size.

Selected and annotated chromosome counts inTaraxacum sect.Palustria Dahlst. (Studies inTaraxacum 3.)

Chromosome counts of 9 species ofTaraxacum sect.Palustria are given. Five species were karyologically examined for the first time, viz.T. trilobifoliumHudziok,T. lissocarpum agg.,T. paucilobumHudziok,T. subalpinumHudziok andT. mendax, a new pentaploid species. Taxonomic and nomenclatural notes are added.

HYBRIDIZATION STUDIES ON FOUR HEXAPLOID SOLANUM SPECIES IN SERIES DEMISSA BUK

The presence of a polyploid series of species in the tuber-bearing Solanums was first demonstrated by Smith (1927) and confirmed by Rybin (1930). The basic chromosome number was considered to be 12, and in addition to numerous diploid, triploid, tetraploid and pentaploid species these authors found one hexaploid, Solanum demissum Lindl. (2n=72). In point of fact the haploid number of 36 had already been noted by Salaman (I926), though the full significance of S. demissum as a higher polyploid was not at that time realized. Until quite recently S. demissum, which is a wild blight resistant species from the high mountains of Mexico, was the only hexaploid known in this group. In the last two or three years, however, four other hexaploid species have been discovered, namely S. brachycarpum Corr., S. guerreroense Corr., S. spectabile (Corr.) Hawkes and S. moscopanum Hawkes. The first three of these are, moreover, quite closely related to S. demissum in their morphological features. Yet, as we shall attempt to show in the present communication, they behave as good species, forming infertile hybrids with each other and with S. demissum. The taxonomic grouping, together with the geographical distribution and a reference to the first published chromosome counts, is given in Table i.