Fundamentally different repetitive element composition of sex chromosomes in Rumex acetosa

Background and AimsDioecious species with well-established sex chromosomes are rare in the plant kingdom. Most sex chromosomes increase in size but no comprehensive analysis of the kind of sequences that drive this expansion has been presented. Here we analyse sex chromosome structure in common sorrel (Rumex acetosa), a dioecious plant with XY₁Y₂ sex determination, and we provide the first chromosome-specific repeatome analysis for a plant species possessing sex chromosomes.MethodsWe flow-sorted and separately sequenced sex chromosomes and autosomes in R. acetosa using the two-dimensional fluorescence in situ hybridization in suspension (FISHIS) method and Illumina sequencing. We identified and quantified individual repeats using RepeatExplorer, Tandem Repeat Finder and the Tandem Repeats Analysis Program. We employed fluorescence in situ hybridization (FISH) to analyse the chromosomal localization of satellites and transposons.Key ResultsWe identified a number of novel satellites, which have, in a fashion similar to previously known satellites, significantly expanded on the Y chromosome but not as much on the X or on autosomes. Additionally, the size increase of Y chromosomes is caused by non-long terminal repeat (LTR) and LTR retrotransposons, while only the latter contribute to the enlargement of the X chromosome. However, the X chromosome is populated by different LTR retrotransposon lineages than those on Y chromosomes.ConclusionsThe X and Y chromosomes have significantly diverged in terms of repeat composition. The lack of recombination probably contributed to the expansion of diverse satellites and microsatellites and faster fixation of newly inserted transposable elements (TEs) on the Y chromosomes. In addition, the X and Y chromosomes, despite similar total counts of TEs, differ significantly in the representation of individual TE lineages, which indicates that transposons proliferate preferentially in either the paternal or the maternal lineage.     

Morphology and behaviour of sex chromosomes during meiosis in Ascaris suum.

The morphology and behaviour of sex chromosomes was studied in A. suum during meiosis. It was found that the five sex chromosomes have their proper characteristic. The largest is submetacentric, of 2 microns mean length. The second largest is acrocentric, mean length of 1.4 mu. The third largest is metacentric, 1.2 mu mean length. The fourth and the fifth are metacentric, of mean length of 1 mu. In primary and secondary spermatocyte cells the sex chromosomes are close to each other, most often in the peripheral part of the cell. During anaphase I the pentad sex chromosomes lie freely between the two sister cells. It is assumed that in anaphase II the five sex chromosomes divide equally and are regularly distributed in the daughter cells. It was found that the chromosomes set of female Ascaris in metaphase I contains 24 bivalent chromosomes n = 24 and of male Ascaris 19 bivalents and 5 univalents. It is assumed that the univalent chromosomes, found in spermatocyte cells, determine sex.     

Oxidative Activities of Mitochondria from Callus and Tumour Tissues3Rumex acetosa L.

The capacity of mitochondria from callus and virus tumour tissuecultures of Rumex acetosa L. to oxidize Krebs-cycle acids wasinvestigated. The rate of oxygen uptake of callus mitochondriawas considerably greater. The rate of substrate oxidation bymitochondria from both tissues decreased with age of the culture.Callus cells were found to contain considerably greater quantitiesof mitochondria than tumour cells. The oxidative activitiesof mitochondria and growth-rates of tissues were affected bythe composition of the culture medium. There was no direct relationshipbetween growth-rate and oxidative activity.     

3 beta,13-dihydroxylated C20 gibberellins from inflorescences of Rumex acetosa L

Using full scan GC-MS a wide range of gibberellins (GAs) was identified in the young inflorescences of the dioecious species Rumex acetosa L., consistent with the ubiquitous early 13-hydroxylation pathway in both male and female plants. In addition, R. acetosa is the first species in which all three 3beta,13-dihydroxylated C(20)-GAs-GA(18), GA(38) and GA(23)-have been identified in the same organism, suggesting an early 3beta,13-dihydroxylation biosynthesis pathway in this species. Authentic GA(18), GA(38) and GA(23) were synthesized and their effects and that of GA(1), a GA common to both pathways, on the time to inflorescence emergence was investigated. GA(1) accelerated the emergence of inflorescences in both male and female plants. In addition some evidence for biological activity per se of the C(20)-GA(38) was obtained.     

3-O-Galloylated Procyanidins from Rumex acetosa L. Inhibit the Attachment of Influenza A Virus

Infections by influenza A viruses (IAV) are a major health burden to mankind. The current antiviral arsenal against IAV is limited and novel drugs are urgently required. Medicinal plants are known as an abundant source for bioactive compounds, including antiviral agents. The aim of the present study was to characterize the anti-IAV potential of a proanthocyanidin-enriched extract derived from the aerial parts of Rumex acetosa (RA), and to identify active compounds of RA, their mode of action, and structural features conferring anti-IAV activity. In a modified MTT (MTT_IAV) assay, RA was shown to inhibit growth of the IAV strain PR8 (H1N1) and a clinical isolate of IAV(H1N1)pdm09 with a half-maximal inhibitory concentration (IC₅₀) of 2.5 µg/mL and 2.2 µg/mL, and a selectivity index (SI) (half-maximal cytotoxic concentration (CC₅₀)/IC₅₀)) of 32 and 36, respectively. At RA concentrations>1 µg/mL plaque formation of IAV(H1N1)pdm09 was abrogated. RA was also active against an oseltamivir-resistant isolate of IAV(H1N1)pdm09. TNF-α and EGF-induced signal transduction in A549 cells was not affected by RA. The dimeric proanthocyanidin epicatechin-3-O-gallate-(4β→8)-epicatechin-3′-O-gallate (procyanidin B2-di-gallate) was identified as the main active principle of RA (IC₅₀ approx. 15 µM, SI≥13). RA and procyanidin B2-di-gallate blocked attachment of IAV and interfered with viral penetration at higher concentrations. Galloylation of the procyanidin core structure was shown to be a prerequisite for anti-IAV activity; o-trihydroxylation in the B-ring increased the anti-IAV activity. In silico docking studies indicated that procyanidin B2-di-gallate is able to interact with the receptor binding site of IAV(H1N1)pdm09 hemagglutinin (HA). In conclusion, the proanthocyanidin-enriched extract RA and its main active constituent procyanidin B2-di-gallate protect cells from IAV infection by inhibiting viral entry into the host cell. RA and procyanidin B2-di-gallate appear to be a promising expansion of the currently available anti-influenza agents.     

In vitro organogenesis in two dioecious species,Rumex acetosella L. and R. acetosa L. (Polygonaceae)

Callus cultures were established from dioecious plant species Rumex acetosella and R. acetosa, using cotyledons, hypocotyls and stem tips of aseptically germinated seedlings as primary explants. Cultures were also established from male and female R. acetosella adult plants, starting from vegetative lateral buds. Cell division was induced using a high 2,4-D concentration, while bud induction and multiplication were stimulated on a medium with high BAP/IAA ratio. Cotyledon fragments of both species produced only rhizogenic calli. Hypocotyl-derived calli of R. acetosella produced buds, while those of R. acetosa showed no bud forming response under these conditions. Bud multiplication occurred in stem tip cultures of both species and in lateral bud cultures of R. acetosella. Calli derived from male plants produced more buds than those from female. Shoots were easily rooted using IBA, and plantlets were effectively transferred to soil. Flowering was not induced in culture. The sex of regenerated male and female plants was not altered by the culture conditions.     

Impaired male meiosis, morphology and distribution pattern of different cytotypes of Bupleurum lanceolatum Wall. (Apiaceae) from the Western Himalayas

Detailed male meiosis, critical morphological observations and distribution pattern of diploid as well as tetraploid cytotypes of the Western Himalayan species, Bupleurum lanceolatum have been evaluated at present. A diploid (n = 8) cytotype is reported from Kashmir, whereas, both diploid (n = 8) and tetraploid (n = 16) cytotypes are available from two districts Kangra and Sirmaur of Himachal Pradesh. Out of these, the tetraploid cytotype makes new addition for the species on a worldwide basis. As per behavior, a tetraploid cytotype is characterized by abnormal meiosis leading to high pollen sterility and size variation of the pollen grains. Morphologically, tetraploids are noted to be luxuriant in comparison to the diploids.     

Contrasting patterns of genetic divergence in two sympatric pseudo-metallophytes: Rumex acetosa L. and commelina communis L

ABSTRACT: BACKGROUND: Patterns of genetic divergence between populations of facultative metallophytes have been investigated extensively. However, most previous investigations have focused on a single plant species making it unclear if genetic divergence shows common patterns or, conversely, is species-specific. The herbs Rumex acetosa L. and Commelina communis L. are two pseudo-metallophytes thriving in both normal and cupriferous soils along the middle and lower reaches of the Yangtze River in China. Their non-metallicolous and metallicolous populations are often sympatric thus providing an ideal opportunity for comparative estimation of genetic structures and divergence under the selective pressure derived from copper toxicity. RESULTS: In the present study, patterns of genetic divergence of R. acetosa and C. communis, including metal tolerance, genetic structure and genetic relationships between populations, were investigated and compared using hydroponic experiments, AFLP, ISSR and chloroplast genetic markers. Our results show a significant reduction in genetic diversity in metallicolous populations of C. communis but not in R. acetosa. Moreover, genetic differentiation is less in R. acetosa than in C. communis, the latter species also shows a clustering of its metallicolous populations. CONCLUSIONS: We propose that the genetic divergences apparent in R. acetosa and C. communis, and the contrasting responses of the two species to copper contamination, might be attributed to the differences in their intrinsic physiological and ecological properties. No simple and generalised conclusions on genetic divergence in pseudo-metallophytes can thus be drawn.     

Behavior of sex chromosomes during meiosis in the house shrew

The behavior of the sex chromosomes during meiosis in the house shrew, Suncus murinus, shows some interesting features. Both X- and Y-chromosomes are large and biarmed and have huge segments of C-band material in noncentromeric areas. A distinct chiasma is formed between the short arms of the X and Y chromosomes and the heterochromatic regions in the bivalents show desynapsis in the form of a bulge.     

Chromosome painting of Y chromosomes and isolation of a Y chromosome-specific repetitive sequence in the dioecious plant Rumex acetosa

The dioecious plant Rumex acetosa has a multiple sex chromosome system: XX in female and XY₁Y₂ in male. Both types of Y chromosome were isolated from chromosome spreads of males by manual microdissection, and their chromosomal DNA was amplified using degenerate oligonucleotide primed-polymerase chain reaction (DOP-PCR). When the biotin-labeled DOP-PCR product was hybridized with competitor DNA in situ, the fluorescent signal painted the Y chromosomes. A library of Y chromosome DNA was constructed from the DOP-PCR product and screened for DNA sequences specific to the Y chromosome. One Y chromosome-specific DNA sequence was identified and designated RAYSI (R. acetosa Y chromosome-specific sequence I). RAYSI is a tandemly arranged repetitive DNA sequence that maps to the 4’,6-diamidino-2-phenylindole bands of both Y chromosomes. Received: 22 December 1998; in revised form: 22 March 1999 / Accepted: 23 March 1999     

Evaluating the DNA barcodes for identification of butterflies from Western Himalayas,Uttarakhand, India

DNA barcodes in species tagging have become a popular tool for taking inventories of species from different groups worldwide. The present study aimed to generate DNA barcodes of butterfly species from the Western Himalayas in Uttarakhand, India. The Indian Western Himalayan region (IWHR) has been explored to a limited extent about butterfly species’ diversity. However, the IWHR is prone to environmental change, and slight variations in climatic conditions can influence species diversity and change butterflies' range. The mitochondrial cytochrome c oxidase I (COI) gene was first used to generate the DNA barcode for butterflies from this region on a broad scale. 28 morphologically identified species, consisting of 102 sequences, were finally grouped into 26 species, with only two species showing ambiguity in species identification. These species had < 3% sequence variations from their neighboring relatives, suggesting cryptic species diversity. Generated sequences were also compared with the GenBank data of conspecific geographical locations, which showed intraspecies variation ranging from 1.3% to 7.3%. It was also noted that butterfly species have both intra and interspecies sequence divergence. In the phylogenetic-based species identification, a total of 28 species belonging to 4 families of butterflies were successfully discriminated, and two species at the genus level, which had high intra-specific divergence (0.025), were considered. However, the high intra-species sequence divergence observed may represent the presence of hidden species.     

Aluminium-induced changes in the profiles of both organic acids and phenolic substances underlie Al tolerance in Rumex acetosa L.

The common sorrel, Rumex acetosa L. is well adapted to acid mineral soils with high availability of phytotoxic Al species. The mechanisms of Al resistance in this species are not established. Our goal was to assess the possible implications of organic acids and phenolic substances in Al detoxification in roots and shoots of this plant. R. acetosa plants were exposed in nutrient solution (pH 4.3) to a non-growth reducing Al concentration of 50 μM Al for 5 days. Exclusion of Al from root tips was visualized by haematoxylin staining. Tissue Al and Ca concentrations were analysed by ICP ES. Root and shoot concentrations of organic acids and phenolic substances were analysed by HPLC. A time-dependent (model II type) Al exclusion pattern in root tips was observed. Nonetheless, high Al concentrations accumulated in roots (1170 μg/g) and shoots (275 μg/g). Aluminium supply enhanced root citrate concentrations but decreased shoot organic acid levels. Aluminium induced high levels of anthraquinone in roots and of catechol, catechin and rutin in shoots. Aluminium resistance in R. acetosa implies both exclusion of Al from root tips and tolerance to high Al tissue concentrations. Citrate in roots and phenolics in shoots may bind Al in non-toxic form. Anthraquinones, as strong antioxidants, may play a role in a general defence response to the root stress.     

Identification of C-banded chromosomes in meiosis of common wheat,Triticum aestivum L.

Summary The C-banding pattern of nine meiotic chromosomes of common wheat (Triticum aestivum L.) as described. In F₁s of crosses between monosomics of Chinese Spring and two Spanish wheat cultivars, univalent chromosomes were used to aid the recognition and analysis of the C-banding pattern for the individual chromosomes. The identification of one chromosome involved in one translocation in Chinese Spring x Pané 247 has been made through heterochromatin bands observed in the chromosomes involved in multivalents.     

Interactions between Apion species (Coleoptera: Curculionidae) and Polygonaceae. I. Apion curtirostre Germ, and Rumex acetosa L.

Abstract.

• 1 Apion curtirostre is the commonest weevil attacking Rumex acetosa in the Lancaster area.
• 2 The ovipositional behaviour, larval development, emergence and hibernation of A. curtirostre are described.
• 3 From dissection of samples of stems of R. acetosa, abundance curves for the stages of A. curtirostre and its chalcid parasitoids were constructed and the between-stage mortalities determined.
• 4 There is an exponential relationship between R. acetosa stem height and number of A. curtirostre eggs laid.
• 5 Male stems of R. acetosa appear earlier and are smaller than female stems. Taller stems, at least in female plants, live longer than shorter ones.
• 6 Apion survival is lower in male than in female stems.
• 7 Stem sex is the primary determinant of opposition choice with stem thickness a secondary determinant.
• 8 A. curtirostre eggs introduced experimentally into stems of four Rumex species survived significiantly better in R. acetosa than in any other species. Survival in R. acetosa female plants was twice that in males.
• 9 Survival of A. curtirostre eggs at densities of 4, 8 and 16 per R. acetosa stem was twice that at densities of 32 and 64 per stem.
• 10 The stem size of female R. acetosa was reduced as the number of attacking weevils increased. There was no significant effect in males. No adverse effect on seed production was detected.
• 11 The nature of the relationship between A. curtirostre and R. acetosa is discussed.

     

Supernumerary chromosomes and their behaviour in meiosis of the holocentric Cuscuta babylonica Ghoisy

A supernumerary chromosome and its behaviour during meiosis is described in the parasitic herb Cuscuta babylonica Choisy (2n = 8 + 1B). This species is characterized by holocentric chromosome behaviour, and the occurrence of a supernumerary here is considered noteworthy.