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Anna M Koltunow - One of the best experts on this subject based on the ideXlab platform.

  • evolution of apomixis loci in pilosella and Hieracium asteraceae inferred from the conservation of apomixis linked markers in natural and experimental populations
    Heredity, 2015
    Co-Authors: Melanie L Hand, Susan D Johnson, Anna Krahulcova, Karsten Oelkers, Hayley Siddons, Jindřich Chrtek, Judith Fehrer, Anna M Koltunow
    Abstract:

    The Hieracium and Pilosella (Lactuceae, Asteraceae) genera of closely related hawkweeds contain species with two different modes of gametophytic apomixis (asexual seed formation). Both genera contain polyploid species, and in wild populations, sexual and apomictic species co-exist. Apomixis is known to co-exist with sexuality in apomictic Pilosella individuals, however, apomictic Hieracium have been regarded as obligate apomicts. Here, a developmental analysis of apomixis within 16 Hieracium species revealed meiosis and megaspore tetrad formation in 1 to 7% of ovules, for the first time indicating residual sexuality in this genus. Molecular markers linked to the two independent, dominant loci LOSS OF APOMEIOSIS (LOA) and LOSS OF PARTHENOGENESIS (LOP) controlling apomixis in Pilosella piloselloides subsp. praealta were screened across 20 phenotyped Hieracium individuals from natural populations, and 65 phenotyped Pilosella individuals from natural and experimental cross populations, to examine their conservation, inheritance and association with reproductive modes. All of the tested LOA and LOP-linked markers were absent in the 20 Hieracium samples irrespective of their reproductive mode. Within Pilosella, LOA and LOP-linked markers were essentially absent within the sexual plants, although they were not conserved in all apomictic individuals. Both loci appeared to be inherited independently, and evidence for additional genetic factors influencing quantitative expression of LOA and LOP was obtained. Collectively, these data suggest independent evolution of apomixis in Hieracium and Pilosella and are discussed with respect to current knowledge of the evolution of apomixis.

  • genetic separation of autonomous endosperm formation aute from the two other components of apomixis in Hieracium
    Sexual Plant Reproduction, 2013
    Co-Authors: Daisuke Ogawa, Susan D Johnson, Steven T Henderson, Anna M Koltunow
    Abstract:

    In apomictic Hieracium subgenus Pilosella species, embryo sacs develop in ovules without meiosis. Embryo and endosperm formation then occur without fertilization, producing seeds with a maternal genotype encased in a fruit (achene). Genetic analyses in H. praealtum indicate a dominant locus (LOA) controls meiotic avoidance, and another dominant locus (LOP) controls both fertilization-independent embryogenesis and endosperm formation. While cytologically examining developmental events in ovules of progeny from crosses between different wild-type and mutant Hieracium apomicts, and a sexual Hieracium species, we identified two plants, AutE196 and AutE24, which have lost the capacity for meiotic avoidance and fertilization-independent embryo formation. AutE196 and AutE24 exhibit autonomous endosperm formation and set parthenocarpic, seedless achenes at a penetrance of 18 %. Viable seed form after pollination. Cytological examination of 102 progeny from a backcross of AutE196 with sexual H. pilosella showed that autonomous endosperm formation is a heritable, dominant, qualitative trait, detected in 51 % of progeny. Variation in quantitative trait penetrance indicates other factors influence its expression. The correlation between autonomous endosperm development and mature parthenocarpic achene formation suggests the former is sufficient to trigger fruit maturation in Hieracium. The developmental component of autonomous endosperm formation is therefore genetically separable from those controlling meiotic avoidance and autonomous embryogenesis in Hieracium and has been denoted as AutE. We postulate that tight linkage of AutE and genes controlling autonomous embryogenesis at the LOP locus in H. praealtum may explain why inheritance of autonomous seed formation is typically observed as a single component.

  • chromosomes carrying meiotic avoidance loci in three apomictic eudicot Hieracium subgenus pilosella species share structural features with two monocot apomicts
    Plant Physiology, 2011
    Co-Authors: Takashi Okada, Susan D Johnson, Karsten Oelkers, Go Suzuki, Andreas Houben, Yasuhiko Mukai, Anna M Koltunow
    Abstract:

    The LOSS OF APOMEIOSIS ( LOA ) locus is one of two dominant loci known to control apomixis in the eudicot Hieracium praealtum . LOA stimulates the differentiation of somatic aposporous initial cells after the initiation of meiosis in ovules. Aposporous initial cells undergo nuclear proliferation close to sexual megaspores, forming unreduced aposporous embryo sacs, and the sexual program ceases. LOA -linked genetic markers were used to isolate 1.2 Mb of LOA -associated DNAs from H. praealtum . Physical mapping defined the genomic region essential for LOA function between two markers, flanking 400 kb of identified sequence and central unknown sequences. Cytogenetic and sequence analyses revealed that the LOA locus is located on a single chromosome near the tip of the long arm and surrounded by extensive, abundant complex repeat and transposon sequences. Chromosomal features and LOA -linked markers are conserved in aposporous Hieracium caespitosum and Hieracium piloselloides but absent in sexual Hieracium pilosella. Their absence in apomictic Hieracium aurantiacum suggests that meiotic avoidance may have evolved independently in aposporous subgenus Pilosella species. The structure of the hemizygous chromosomal region containing the LOA locus in the three Hieracium subgenus Pilosella species resembles that of the hemizygous apospory-specific genomic regions in monocot Pennisetum squamulatum and Cenchrus ciliaris . Analyses of partial DNA sequences at these loci show no obvious conservation, indicating that they are unlikely to share a common ancestral origin. This suggests convergent evolution of repeat-rich hemizygous chromosomal regions containing apospory loci in these monocot and eudicot species, which may be required for the function and maintenance of the trait.

  • sexual and apomictic reproduction in Hieracium subgenus pilosella are closely interrelated developmental pathways
    The Plant Cell, 2003
    Co-Authors: Matthew R Tucker, Anaclaudia G Araujo, Nicholas A Paech, Valerie Hecht, E D L Schmidt, Janbart Rossell, Sacco C De Vries, Anna M Koltunow
    Abstract:

    Seed formation in flowering plants requires meiosis of the megaspore mother cell (MMC) inside the ovule, selection of a megaspore that undergoes mitosis to form an embryo sac, and double fertilization to initiate embryo and endosperm formation. During apomixis, or asexual seed formation, in Hieracium ovules, a somatic aposporous initial (AI) cell divides to form a structurally variable aposporous embryo sac and embryo. This entire process, including endosperm development, is fertilization independent. Introduction of reproductive tissue marker genes into sexual and apomictic Hieracium showed that AI cells do not express a MMC marker. Spatial and temporal gene expression patterns of other introduced genes were conserved commencing with the first nuclear division of the AI cell in apomicts and the mitotic initiation of embryo sac formation in sexual plants. Conservation in expression patterns also occurred during embryo and endosperm development, indicating that sexuality and apomixis are interrelated pathways that share regulatory components. The induction of a modified sexual reproduction program in AI cells may enable the manifestation of apomixis in Hieracium.

  • apomixis is not developmentally conserved in related genetically characterized Hieracium plants of varying ploidy
    Sexual Plant Reproduction, 2000
    Co-Authors: Anna M Koltunow, Susan D Johnson, Ross Bicknell
    Abstract:

    Apomixis is facultative in characterized members of the genus Hieracium. The three components that comprise the apomictic mechanism include apospory followed by autonomous embryo and endosperm formation. The time of aposporous embryo sac initiation and mode of embryo sac formation are different in Hieracium piloselloides (D3) and Hieracium aurantiacum (A3.4). Genetic studies have shown that a single dominant locus encodes all three components of apomixis in both species (Bicknell et al. 2000). We histologically examined a range of related, genetically characterized apomictic Hieracium plants derived from D3 and A3.4 to assess conservation of the apomictic mechanism in different genetic backgrounds. The plants varied in ploidy, and also in the amount of DNA introduced from sexual Hieracium pilosella (P4). An apomictic hybrid from a cross between the two apomicts was also examined. The developmental processes observed in the parental apomicts were not conserved in the examined plants and alterations occurred in the components of apomixis. One plant also exhibited adventitious embryony. The results show that other genetic factors can modify apomixis with respect to time of initiation, spatial location, and mode of developmental progression. Both the apomictic locus and the modifiers are essential for efficient penetrance of the trait in Hieracium. Some of the findings in Hieracium correspond with observations in Ranunculus and this is discussed in terms of models for apomictic development and the control of apomixis in crops.

Torbjörn Tyler - One of the best experts on this subject based on the ideXlab platform.

  • typification of species of Hieracium s stricto described by norrlin from central scandinavia
    Annales Botanici Fennici, 2015
    Co-Authors: Torbjörn Tyler, Alexander N Sennikov
    Abstract:

    Twenty-six names of taxa of Hieracium sections Hieracium, Bifida and Vulgata (Asteraceae) described by the Finnish author J.P. Norrlin based on material from central Sweden and adjacent Norway and originally published in 1888 are lectotypified, and their applications are discussed. The replacement name H. cognatum T. Tyler & Sennikov is proposed as a substitute for the illegitimate H. propinquum (Norrl. ex Hamb.) Johanss., non Sudre.

  • Ten polymorphic microsatellite markers for Hieracium s.s. (Asteraceae)
    Conservation Genetics Resources, 2010
    Co-Authors: Jane Jönsson, Maren Wellenreuther, Torbjörn Tyler
    Abstract:

    Eight novel microsatellite markers were developed for Hieracium s.s. (excluding Pilosella) using a modified FIASCO protocol, and two out of nine microsatellites that were originally developed for Pilosella officinarum were optimised for Hieracium s.s.. All ten microsatellites consistently amplified loci from a wide range of representatives from north and central European species of various sections of the genus. When tested on 19 individuals, nine microsatellites were found to be highly polymorphic with 6–29 alleles, while one microsatellite marker was monomorphic. Cross-amplification showed that six of the ten microsatellites also amplified products in one taxon of Pilosella, P. floribunda × officinarum

  • ploidy level analysis of apomictic Hieracium asteraceae reveal unexpected patterns and variation
    Nordic Journal of Botany, 2009
    Co-Authors: Torbjörn Tyler, Jane Jönsson
    Abstract:

    The DNA ploidy level of 673 accessions belonging to 238 species of Hieracium have been analyzed by flow cytometry. 222 of the species were of Scandinavian origin as members of the exclusively apomictic H. sectt. Bifida, Hieracium, Oreadea, Tridentata and Vulgata. For the overwhelming majority of the species, the ploidy level (or chromosme number) has never been investigated before. Approximately 50 % of the Scandinavian species, previously believed to be exclusively triploid, were found to be tetraploid. In addition, two pentaploid samples, viz. H. intermarginatum Johanss. & Sam. from Sweden and H. cf. plumbeum Blytt & Fr. from Germany, were found. Although two or more accessions from geographically remote sites were analyzed for approximately 50 % of the Scandinavian species, only 2 (< 2 %) taxonomically undisputed species were found to consist of plants with more than one ploidy level. An intriguing pattern was revealed among Scandinavian members of H. sectt. Bifida and Vulgata when ploidy level and morphometric variation was compared, viz. the most typical or extreme representatives of these sections were found to be exclusively triploid whereas tetraploids dominate among species with intermediate morphology and among species morphologically intermediate between these sections and H. sect. Hieracium. This pattern may indicate that the tetraploids, which tend to have mainly northern distributions, have originated as the result of rare sexual hybridizations between triploid members of different sections, plausibly during or after the northward migration of the parental linages after the last glaciation. The results are believed to be highly relevant for understanding the processes of evolution and speciation within the predominantly apomictic genus Hieracium, but it is emphazised that additional data from e.g. molecular markers and pollen viability analysis are needed before any trustworthy conclusions can be made as far as evolutionary processes are concerned. (Less)

  • Lectotypifications and notes on the application of names of Hieracium sect. Hieracium, sect. Bifida and sect. Vulgata (Asteraceae) based on material from the province of Dalarna, central Sweden
    Nordic Journal of Botany, 2009
    Co-Authors: Torbjörn Tyler
    Abstract:

    Lectotypes are designated for 174 names of taxa described based on material from the Swedish province of Dalarna and accepted to belong to Hieracium sect. Hieracium, sect. Bifida and sect. Vulgata. The taxonomic and nomenclatural implications, i.e. taxonomic synonyms and infraspecific taxa not worthy of taxonomic recognition, of the lectotypifications are discussed. Three new combinations, H. mundulifolium (Johanss.) T. Tyler, H. oligasterum (Johanss. & Sam.) T. Tyler and H. transtrandense T. Tyler, are proposed to accommodate the infraspecific taxa H. gilvocaniceps Johanss. var. mundulifolium Johanss., H. expallidiforme (Dahlst. ex. Stenstr.) Dahlst. var. oligasterum Johanss. & Sam. and H. insuccatum Johanss. var. occidentale Johanss. & Sam. respectively, when treated at the rank of species.

  • lectotypification of names of Hieracium asteraceae described from the province of varmland
    Annales Botanici Fennici, 2007
    Co-Authors: Torbjörn Tyler
    Abstract:

    Forty-one names of species and varieties of Hieracium sect. Hieracium, H. sect. Vulgata and H. sect. Bifida originally described from the province of Varmland, western central Sweden, are lectotypified.

Jindřich Chrtek - One of the best experts on this subject based on the ideXlab platform.

  • Distribution of mountain hawkweeds (Hieracium s. str.) in the Hrubý Jeseník Mountains
    Acta Musei Silesiae: Scientiae Naturales, 2017
    Co-Authors: Jiří Kocián, Jindřich Chrtek
    Abstract:

    Abstract Field revision of current distribution of mountain hawkweeds (Hieracium s. str.) in the Hrubý Jeseník Mts was undertaken. Hieracium atratum, H. chlorocephalum, H. engleri, H. grabowskianum and H. plumbeum, whose last occurrence was documented many decades or even a century ago, were rediscovered. H. plumbeum was even found in new localities. The occurrence of H. alpinum, H. bifidum, H. chrysostyloides, H. inuloides, H. nigritum, H. prenanthoides, H. silesiacum, H. stygium and H. villosum was ascertained at many of their historical localities and a few new localities were found too. A neophyte species H. mixtum was discovered. Hieracium moravicum was not found. Accurate locality description and population size are provided for each finding. Herbarium revision and excerption of crucial literature were performed to provide historical distribution. Distributional changes as well as threatening and beneficial factors influencing Hieracium species in the Hrubý Jeseník Mts are discussed.

  • Autumn hawkweed (Hieracium sabaudum) in the Czech Republic
    2016
    Co-Authors: Petra Bidmanová, Olga Rotreklová, Jiří Danihelka, Jindřich Chrtek
    Abstract:

    The distribution of Autumn hawkweed Hieracium sabaudum in the Czech Republic is examined, based on specimens held by 28 public herbaria. This species, classified within Hieracium sect. Foliosa, is one of 58 native hawkweeds within the Czech flora. In total 2793 herbarium specimens of H. sabaudum collected in the country were revised, of which 1668 (i.e. approx. 71%) were originally identified correctly (including taxonomic synonyms). Based on the number of specimens revised and data from botanical databases, the distribution map presented here may be considered representative. Hieracium sabaudum occurs in most parts of the country, although it is rare in mountain areas, or absent from them. In the Czech National Phytosociological Database, its occurrence is recorded over a broad scale of various plant communities, most frequently in oak-hornbeam, thermophilous oak and pine forests and their fringes, in scrub, heath and in various types of secondary habitats such as quarries and roadsides. Using flow cytometry measurements and chromosome counts, ten plants originating from five populations were shown to be triploid (2n ~ 3x) and one plant was 2n = 27.

  • evolution of apomixis loci in pilosella and Hieracium asteraceae inferred from the conservation of apomixis linked markers in natural and experimental populations
    Heredity, 2015
    Co-Authors: Melanie L Hand, Susan D Johnson, Anna Krahulcova, Karsten Oelkers, Hayley Siddons, Jindřich Chrtek, Judith Fehrer, Anna M Koltunow
    Abstract:

    The Hieracium and Pilosella (Lactuceae, Asteraceae) genera of closely related hawkweeds contain species with two different modes of gametophytic apomixis (asexual seed formation). Both genera contain polyploid species, and in wild populations, sexual and apomictic species co-exist. Apomixis is known to co-exist with sexuality in apomictic Pilosella individuals, however, apomictic Hieracium have been regarded as obligate apomicts. Here, a developmental analysis of apomixis within 16 Hieracium species revealed meiosis and megaspore tetrad formation in 1 to 7% of ovules, for the first time indicating residual sexuality in this genus. Molecular markers linked to the two independent, dominant loci LOSS OF APOMEIOSIS (LOA) and LOSS OF PARTHENOGENESIS (LOP) controlling apomixis in Pilosella piloselloides subsp. praealta were screened across 20 phenotyped Hieracium individuals from natural populations, and 65 phenotyped Pilosella individuals from natural and experimental cross populations, to examine their conservation, inheritance and association with reproductive modes. All of the tested LOA and LOP-linked markers were absent in the 20 Hieracium samples irrespective of their reproductive mode. Within Pilosella, LOA and LOP-linked markers were essentially absent within the sexual plants, although they were not conserved in all apomictic individuals. Both loci appeared to be inherited independently, and evidence for additional genetic factors influencing quantitative expression of LOA and LOP was obtained. Collectively, these data suggest independent evolution of apomixis in Hieracium and Pilosella and are discussed with respect to current knowledge of the evolution of apomixis.

  • intra individual polymorphism in diploid and apomictic polyploid hawkweeds Hieracium lactuceae asteraceae disentangling phylogenetic signal reticulation and noise
    BMC Evolutionary Biology, 2009
    Co-Authors: Judith Fehrer, Jindřich Chrtek, Karol Krak
    Abstract:

    Background Hieracium s.str. is a complex species-rich group of perennial herbs composed of few sexual diploids and numerous apomictic polyploids. The existence of reticulation and the near-continuity of morphological characters across taxa seriously affect species determination, making Hieracium one of the best examples of a 'botanist's nightmare'. Consequently, its species relationships have not previously been addressed by molecular methods. Concentrating on the supposed major evolutionary units, we used nuclear ribosomal (ETS) and chloroplast (trnT-trnL) sequences in order to disentangle the phylogenetic relationships and to infer the origins of the polyploids.

  • incongruent plastid and nuclear dna phylogenies reveal ancient intergeneric hybridization in pilosella hawkweeds Hieracium cichorieae asteraceae
    Molecular Phylogenetics and Evolution, 2007
    Co-Authors: Judith Fehrer, Jindřich Chrtek, Birgit Gemeinholzer, Siegfried Brautigam
    Abstract:

    Phylogenetic relationships for Hieracium subgen. Pilosella were inferred from chloroplast (trnT–trnL, matK) and nuclear (ITS) sequence data. Chloroplast markers revealed the existence of two divergent haplotype groups within the subgenus that did not correspond to presumed relationships. Furthermore, chloroplast haplotypes of the genera Hispidella and Andryala nested each within one of these groups. In contrast, ITS data were generally in accord with morphology and other evidence and were therefore assumed to reflect the true phylogeny. They revealed a sister relationship between Pilosella and Hispidella and a joint clade of Hieracium subgenera Hieracium and Chionoracium (Stenotheca) while genus Andryala represented a third major lineage of the final ingroup cluster. Detailed analysis of trnT–trnL character state evolution along the ITS tree suggested two intergeneric hybridization events between ancestral lineages that resulted in cytoplasmic transfer (from Hieracium/Chionoracium to Pilosella, and from the introgressed Pilosella lineage to Andryala). These chloroplast capture events, the first of which involved a now extinct haplotype, are the most likely explanation for the observed incongruencies between plastid and nuclear DNA markers.

Silvana Petrovic - One of the best experts on this subject based on the ideXlab platform.

  • sesquiterpene lactones from the methanol extracts of twenty eight Hieracium species from the balkan peninsula and their chemosystematic significance
    Phytochemistry, 2018
    Co-Authors: Violeta Milutinovic, Marjan Niketic, Ljubos Usjak, Dejan Nikolic, Aleksej Krunic, Milos Petkovic, Silvana Petrovic
    Abstract:

    Abstract Four sesquiterpene lactones (SLs), including three undescribed proline-SL conjugates, the guaianolides calophyllamine A and 8-epiixerisamine A, and the eudesmanolide calophyllamine B, were isolated from the methanol extract of Hieracium calophyllum R. Uechtr. (Compositae) flowering heads. Another known guaianolide, crepiside E, was detected in Hieracium L. species for the first time. Their structures were elucidated using extensive 1D and 2D NMR spectroscopy in combination with HRMS. The isolated SLs were used as external standards for qualitative and quantitative LC-MS analysis of the dry methanol extracts of the flowering aerial parts of 28 Hieracium species from the Balkan Peninsula. Guaianolides were the dominant SLs in 27 species studied. The chemosystematic significance of detected SLs was evaluated using multivariate statistics (PCA, nMDS and UPGMA). Differentiation between the main groups was well supported. All four compounds significantly and equally contributed to the differences between the species. In addition, the eudesmanolide calophyllamine B could be a significant chemosystematic marker for H. sect. Villosa (Griseb.) Gremli s.l. and Glauciformia (Freyn) Zahn–Italica (Fr.) Av. Touv.

  • methanol extracts of 28 Hieracium species from the balkan peninsula comparative lc ms analysis chemosystematic evaluation of their flavonoid and phenolic acid profiles and antioxidant potentials
    Phytochemical Analysis, 2018
    Co-Authors: Violeta Milutinovic, Marjan Niketic, Ljubos Usjak, Dejan Nikolic, Aleksej Krunic, Christian Zidorn, Silvana Petrovic
    Abstract:

    Introduction Hieracium s. str. represents one of the largest and most complex genera of flowering plants. As molecular genetics seems unlikely to disentangle intricate relationships within this reticulate species complex, analysis of flavonoids and phenolic acids, known as good chemosystematic markers, promise to be more reliable. Data about pharmacological activity of Hieracium species are scarce. Objective Evaluation of the chemosystematic significance of flavonoids and phenolic acids of methanol extracts of aerial flowering parts of 28 Hieracium species from the Balkans. Additionally, investigation of antioxidant potentials of the extracts. Methods Comparative qualitative and quantitative analysis of flavonoids and phenolic acids was performed by LC–MS. Multivariate statistical data analysis included non-metric multidimensional scaling (nMDS), unweighted pair-group arithmetic averages (UPGMA) and principal component analysis (PCA). Antioxidant activity was evaluated using three colorimetric tests. Results Dominant phenolics in almost all species were luteolin type flavonoids, followed by phenolic acids. Although the investigated Hieracium species share many compounds, the current classification of the genus was supported by nMDS and UPGMA analyses with a good resolution to the group level. Hieracium naegelianum was clearly separated from the other investigated species. Spatial and ecological distances of the samples were likely to influence unexpected differentiation of some groups within H. sect. Pannosa. The vast majority of dominant compounds significantly contributed to differences between taxa. The antioxidant potential of the extracts was satisfactory and in accordance with their phenolics composition. Conclusions Comparative LC–MS analysis demonstrated that flavonoids and phenolic acids are good indicators of chemosystematic relationships within Hieracium, particularly between non-hybrid species and groups from the same location. Copyright © 2017 John Wiley & Sons, Ltd.

Patrik Mráz - One of the best experts on this subject based on the ideXlab platform.

  • chromosome numbers and reproductive systems in selected species of Hieracium and pilosella asteraceae from romania
    2004
    Co-Authors: Patrik Mráz, Zbigniew Szelag
    Abstract:

    Chromosome numbers are given for 17 taxa of the genus Hieracium and 4 taxa of the genus Pilosella originating from Romanian Eastern and Southern Carpathians: Hieracium alpinum (2n = 18), H. atratiforme s. lato (2n = 36), H. bifidum s. lato (2n = 27, 36), H. inuloides (2n = 27), H. jankae (2n = 27), H. lachenalii s. lato (2n = 27), H. lubricicaule (2n = 27), H. kotschyanum (2n = 27), H. magocsyanum (2n = 27), H. ostii-bucurae (2n = 27), H. praecurrens s. lato (2n = 27), H. ratezaticum (2n = 36), H. sabaudum s. lato (2n = 27), H. telekianum (2n = 27), H. tomiasae (2n = 27), H. tubulare (2n = 27), H. transylvanicum (2n = 18), Pilosella aurantiaca (2n = 36, 45), P. bauhinii (2n = 45), P. cymosa (2n = 36) and P. pavichii (2n = 18). For the first time the chromosome numbers are reported for the following taxa: H. atratiforme s. lato, H. jankae, H. lubricicaule, H. kotschyanum, H. magocsyanum, H. ostii-bucurae, H. telekianum, H. tomiasae and H. tubulare. Apomictic mode of reproduction was proved in triploids H. jankae, H. lubricicaule, H. kotschyanum, H. magocsyanum, H. ostii-bucurae, H. telekianum, H. tomiasae and H. tubulare by emasculation experiments. Diploid populations of Hieracium alpinum were confirmed in the Southern and Romanian Eastern Carpathians. Because diploid H. alpinum occurs just in the Eastern and Southern Carpathians and nowhere else, these parts of its area of distribution may be considered as glacial refugia for this species. The Skhidni Beskidi Mts. (the most western part of the Eastern Carpathians) probably represented a strong barrier of postglacial migrations of some diploid Hieracium taxa from the Eastern Carpathians towards the Western Carpathians.

  • chromosome numbers and breeding systems in some species of Hieracium subgen pilosella from central europe
    Preslia, 2002
    Co-Authors: Olga Rotreklová, Anna Krahulcova, Danuse Vaňkova, Tomas Peckert, Patrik Mráz
    Abstract:

    Chromosome numbers are given for 17 taxa of Hieracium subgen. Pilosella originating from Central Europe: Hieracium apatelium, H. aurantiacum, H. bauhini, H. brachiatum, H. densiflorum, H. echioides, H. floribundum, H. glomeratum, H. guthnickianum, H. lactucella, H. onegense, H. pilosella, H piloselliflorum, H. piloselloides, H. rothianum, H. schultesii and hybrid H. floribundum x H. aurantiacum. Breeding system in seven taxa was studied.

  • Genetic Variation in the Hieracium rohacsense Group (Hieracium sect. Alpina)
    2001
    Co-Authors: Patrik Mráz, Jindrich Chrtek, Jan Kirschnet
    Abstract:

    Summary MRAZ P., CHRTEK J. jun. & KIRSCHNER J. 2001. Genetic variation in the Hieracium rohacsense group {Hieracium sect. Alpina). - Phyton (Horn, Austria) 41 (2): 269-276, 2 figures. - English with German summary. Five isozyme systems (AAT, ADH, LAP, PGM, SKD) were studied in two tetraploid apomictic taxa of the Hieracium rohacsense group (Hieracium sect. Alpina). No intraand inter-population variation was found in H. rohacsense KIT., endemic to the West Carpathians, which is in accordance with its narrow morphological variation. In contrast, a probably still unnamed tetraploid taxon from Mt. Pop Ivan (Ukrainian East Carpathians) belonging to the H. rohacsense group was represented by three phenotypes detected in one population. The role of diploid sexual taxa occurring in the alpine and subalpine belts of the Ukrainian East Carpathians in maintainig genetic variability is discussed. Apart from morphological characters the two closely related taxa included in this study can be separated also by their patterns of Pgm-1 locus.

  • Lectotypification of the name Hieracium rohacsense Kit. (Compositae)
    Willdenowia, 1999
    Co-Authors: Patrik Mráz, Karol Marhold
    Abstract:

    Abstract Mraz, P. & Marhold, K.: Lectotypification of the name Hieracium rohacsense Kit. (Compositae). — Willdenowia 29: 41–44. 1999. — ISSN 0511-9618. A lectotype is designated for Hieracium rohacsense, the name of a species restricted in its distribution to the subalpine belt of the W Carpathians with two doubtful localities in the E Carpathians. The lectotype is a specimen collected in the Zapadne Tatry (Rohace) Mts in Slovakia and kept in the Kitaibel herbarium in the Hungarian Museum of Natural History (BP) in Budapest.