New records and noteworthy data of plants, algae and fungi in SE Europe and adjacent regions, 12

This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: red algae Hildenbrandia rivularis, saprotrophic fungus Cryptomarasmius corbariensis, lichenised fungi Lecanora stenotropa, Micarea misella and Sticta sylvatica, liverworts Fossombronia caespitiformis and Peltolepis quadrata, mosses Dicranoweisia cirrata and Fissidens exilis, horsetail Equisetum × moorei, gymnosperm Juniperus virginiana, monocots Galanthus reginae-olgae subsp. vernalis and Spiranthes spiralis and dicots Linaria pelisseriana, Parthenocissus quinquefolia, Pilosella rhodopea and Taraxacum erythrospermum are given within SE Europe and adjacent regions

New records and noteworthy data of plants, algae and fungi in SE Europe and adjacent regions, 11

This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: red algae Sheathia confusa, parasitic fungus Anthracoidea caryophylleae, mycorrhizal fugus Hydnellum caeruleum, bryoparasitic fungus Octospora erzbergeri, liverwort Cephaloziella baumgartneri, mosses Hamatocaulis vernicosus, Streblotrichum convolutum var. commutatum and Ulota crispula, monocots Ophrys bertolonii subsp. bertolonii, Ophrys scolopax subsp. cornuta and Spiranthes spiralis and dicots Androsace hedraeantha, Hieracium mrazii, Ramonda nathaliae and Triglochin palustris are given within SE Europe and adjacent regions

Reproduction Modes and Conservation Implications in Three Polyploid Sorbus Stenoendemics in Eastern Slovakia (Central Europe)

The remarkable species diversity of the genus Sorbus is a result of polyploidization and frequent hybridization between interacting species of different cytotypes. Moreover, hybridization is possible between several parental taxa. Gametophytic apomixis, which is common among polyploid Sorbus taxa, indicates the role of clonal reproduction in the evolutionary stabilization of hybridogeneous genotypes. The precise determination of the origin of seeds and their quantitative evaluation may elucidate inter-cytotype interactions, the potential role of mixed-cytotype populations in evolutionary success, and the long-term survival of some hybrid species. We investigated the reproduction modes of selected species of Sorbus in mixed-cytotype populations in eastern Slovakia, Central Europe. We determined the pollen quality, seed production rate, and the ploidy level of mature trees, as well as the origin of the embryo and endosperm in seeds of the stenoendemics S. amici-petri, S. dolomiticola, and S. hornadensis. The tetraploids S. amici-petri and S. hornadensis are characterized by regular and highly stainable pollen grains and reproduce predominantly via pseudogamous apomixis. In contrast, triploid S. dolomiticola usually has oval, heterogenous, and weakly stainable pollen grains, suggesting male meiotic irregularities. Although seeds originate via pseudogamous apomixis in S. dolomiticola as well, the ploidy level of sperm cells participating in the fertilization of central cells is usually determined by co-occurring species of different cytotypes. This suggests that maintaining mating partners is necessary for the long-term survival of a triploid species. We documented rare BIII hybrids and the residual sexuality in tetraploids. The distribution of seeds of meiotic and apomeiotic origins in S. amici-petri shows bimodal characteristics; however, genotypes with predominantly sexual seed types are rare. Reproduction modes documented in polyploid stenoendemics of Sorbus and inferred microevolutionary intercytotype relationships highlight the mixed-cytotype populations as the source of biodiversity in apomictic plant complexes. We suggest that conservation efforts should focus on maintaining the species and cytotypic diversity of Sorbus populations, especially when it comes to the conservation of triploid species

Variability of Reproduction Pathways in the Central-European Populations of Hawthorns with Emphasis on Triploids

The role of apomeiosis, parthenogenesis, and pseudogamy in the asexual reproduction of some plant groups has not been fully elucidated in relation to species diversification. Quantitative analyses of seed origin may help in gaining better understanding of intercytotypic interactions. Asexual reproduction associated with polyploidy and frequent hybridization plays a crucial role in the evolutionary history of the genus Crataegus in North America. In Europe, the genus represents a taxonomically complex and very difficult species group not often studied using a modern biosystematic approach. We investigated the reproduction pathways in mixed-cytotype populations of selected taxa of Crataegus in eastern Slovakia, Central Europe. The investigated accessions were characterized by seed production data and the ploidy level of mature plants as well as the embryo and endosperm tissues of their seeds determined via flow cytometry. Diploid and polyploid hawthorns reproduce successfully; they also produce high numbers of seeds. An exception is represented by an almost sterile triploid. Diploids reproduce sexually. Polyploids shift to asexual reproduction, but pseudogamy seems to be essential for regular seed development. In rare cases, fertilization of unreduced gametes occurs, which offers opportunity for the establishment of new polyploid cytotypes between diploid sexuals and polyploid asexuals. Opposite to sexual diploids, triploids are obligate, and tetraploids almost obligate apomicts. Apomixis is considered to help stabilize individual weakly differentiated polyploid microspecies. Pseudogamy is a common feature and usually leads to unbalanced maternal to paternal contribution in the endosperm of triploid accessions. Parental contribution to endosperm gene dosage is somehow relaxed in triploids. Our Crataegus plant system resembles reproduction in the diploids and polyploids of North American hawthorns. Our data provide support for the hypothesis that polyploidization, shifts in reproduction modes, and hybridization shape the genus diversity also in Central Europe

Patterns of pollen stainability in polyploids of the genus Onosma (Boraginaceae)

Background and aims – The genus Onosma (Boraginaceae) is a taxonomically and phylogenetically very complex plant group, with several taxa of hybrid or polyploid origin. An extensive pollen viability survey within the genus could help to solve some evolutionary or taxonomic incertainties within the genus, but it has never been performed. The aim of the present study is to determine the degree of pollen viability of selected species of various ploidy levels and to investigate if microevolutionary processes, such as polyploidization and hybridization, are associated with variation in pollen viability. Methods – Pollen staining with lactophenol blue was chosen as an indirect method for determining pollen viability. Ploidy level information was obtained from an extensive literature search. In mixed populations, the ploidy level of individuals was determined based on flow cytometry screening. Key results – Considerable variation in pollen stainability is present among taxa of Onosma . Pollen stainability is high in most diploids (72–98% in mean), allotetraploids (90%) and allohexaploids (97%), but lower in autotetraploids (71%) and allotriploids (2–49%). At the population level, considerable variation in pollen stainability was found in the allotriploid O. arenaria (14–83%), while the taxonomically related allotetraploid O. pseudoarenaria is less variable (71–99%). Conclusion – This study shows the value of the staining method in the study of the genus Onosma . Low pollen stainability appears to be associated with autopolyploidization as well as recent hybridization processes suggesting the presence of microsporogenesis or microgametogenesis abnormalities. In contrast, pollen stainability is high in stabilized allopolyploids indicating proper meiosis with maintenance of homologous pairing of parental chromosomes and correct pollen development

Patterns of pollen stainability in polyploids of the genus Onosma (Boraginaceae)

Background and aims – The genus Onosma (Boraginaceae) is a taxonomically and phylogenetically very complex plant group, with several taxa of hybrid or polyploid origin. An extensive pollen viability survey within the genus could help to solve some evolutionary or taxonomic incertainties within the genus, but it has never been performed. The aim of the present study is to determine the degree of pollen viability of selected species of various ploidy levels and to investigate if microevolutionary processes, such as polyploidization and hybridization, are associated with variation in pollen viability. Methods – Pollen staining with lactophenol blue was chosen as an indirect method for determining pollen viability. Ploidy level information was obtained from an extensive literature search. In mixed populations, the ploidy level of individuals was determined based on flow cytometry screening. Key results – Considerable variation in pollen stainability is present among taxa of Onosma . Pollen stainability is high in most diploids (72–98% in mean), allotetraploids (90%) and allohexaploids (97%), but lower in autotetraploids (71%) and allotriploids (2–49%). At the population level, considerable variation in pollen stainability was found in the allotriploid O. arenaria (14–83%), while the taxonomically related allotetraploid O. pseudoarenaria is less variable (71–99%). Conclusion – This study shows the value of the staining method in the study of the genus Onosma . Low pollen stainability appears to be associated with autopolyploidization as well as recent hybridization processes suggesting the presence of microsporogenesis or microgametogenesis abnormalities. In contrast, pollen stainability is high in stabilized allopolyploids indicating proper meiosis with maintenance of homologous pairing of parental chromosomes and correct pollen development

Reproduction Modes and Conservation Implications in Three Polyploid <i>Sorbus</i> Stenoendemics in Eastern Slovakia (Central Europe)

The remarkable species diversity of the genus Sorbus is a result of polyploidization and frequent hybridization between interacting species of different cytotypes. Moreover, hybridization is possible between several parental taxa. Gametophytic apomixis, which is common among polyploid Sorbus taxa, indicates the role of clonal reproduction in the evolutionary stabilization of hybridogeneous genotypes. The precise determination of the origin of seeds and their quantitative evaluation may elucidate inter-cytotype interactions, the potential role of mixed-cytotype populations in evolutionary success, and the long-term survival of some hybrid species. We investigated the reproduction modes of selected species of Sorbus in mixed-cytotype populations in eastern Slovakia, Central Europe. We determined the pollen quality, seed production rate, and the ploidy level of mature trees, as well as the origin of the embryo and endosperm in seeds of the stenoendemics S. amici-petri, S. dolomiticola, and S. hornadensis. The tetraploids S. amici-petri and S. hornadensis are characterized by regular and highly stainable pollen grains and reproduce predominantly via pseudogamous apomixis. In contrast, triploid S. dolomiticola usually has oval, heterogenous, and weakly stainable pollen grains, suggesting male meiotic irregularities. Although seeds originate via pseudogamous apomixis in S. dolomiticola as well, the ploidy level of sperm cells participating in the fertilization of central cells is usually determined by co-occurring species of different cytotypes. This suggests that maintaining mating partners is necessary for the long-term survival of a triploid species. We documented rare BIII hybrids and the residual sexuality in tetraploids. The distribution of seeds of meiotic and apomeiotic origins in S. amici-petri shows bimodal characteristics; however, genotypes with predominantly sexual seed types are rare. Reproduction modes documented in polyploid stenoendemics of Sorbus and inferred microevolutionary intercytotype relationships highlight the mixed-cytotype populations as the source of biodiversity in apomictic plant complexes. We suggest that conservation efforts should focus on maintaining the species and cytotypic diversity of Sorbus populations, especially when it comes to the conservation of triploid species

Spatial and Temporal Patterns of Endopolyploidy in Mosses

Somatic polyploidy or endopolyploidy is common in the plant kingdom; it ensures growth and allows adaptation to the environment. It is present in the majority of plant groups, including mosses. Endopolyploidy had only been previously studied in about 65 moss species, which represents less than 1% of known mosses. We analyzed 11 selected moss species to determine the spatial and temporal distribution of endopolyploidy using flow cytometry to identify patterns in ploidy levels among gametophytes and sporophytes. All of the studied mosses possessed cells with various ploidy levels in gametophytes, and four of six species investigated in sporophytic stage had endopolyploid sporophytes. The proportion of endopolyploid cells varied among organs, parts of gametophytes and sporophytes, and ontogenetic stages. Higher ploidy levels were seen in basal parts of gametophytes and sporophytes than in apical parts. Slight changes in ploidy levels were observed during ontogenesis in cultivated mosses; the youngest (apical) parts of thalli tend to have lower levels of endopolyploidy. Differences between parts of cauloid and phylloids of Plagiomnium ellipticum and Polytrichum formosum were also documented; proximal parts had higher levels of endopolyploidy than distal parts. Endopolyploidy is spatially and temporally differentiated in the gametophytes of endopolyploid mosses and follows a pattern similar to that seen in angiosperms

Variability of Reproduction Pathways in the Central-European Populations of Hawthorns with Emphasis on Triploids

The role of apomeiosis, parthenogenesis, and pseudogamy in the asexual reproduction of some plant groups has not been fully elucidated in relation to species diversification. Quantitative analyses of seed origin may help in gaining better understanding of intercytotypic interactions. Asexual reproduction associated with polyploidy and frequent hybridization plays a crucial role in the evolutionary history of the genus Crataegus in North America. In Europe, the genus represents a taxonomically complex and very difficult species group not often studied using a modern biosystematic approach. We investigated the reproduction pathways in mixed-cytotype populations of selected taxa of Crataegus in eastern Slovakia, Central Europe. The investigated accessions were characterized by seed production data and the ploidy level of mature plants as well as the embryo and endosperm tissues of their seeds determined via flow cytometry. Diploid and polyploid hawthorns reproduce successfully; they also produce high numbers of seeds. An exception is represented by an almost sterile triploid. Diploids reproduce sexually. Polyploids shift to asexual reproduction, but pseudogamy seems to be essential for regular seed development. In rare cases, fertilization of unreduced gametes occurs, which offers opportunity for the establishment of new polyploid cytotypes between diploid sexuals and polyploid asexuals. Opposite to sexual diploids, triploids are obligate, and tetraploids almost obligate apomicts. Apomixis is considered to help stabilize individual weakly differentiated polyploid microspecies. Pseudogamy is a common feature and usually leads to unbalanced maternal to paternal contribution in the endosperm of triploid accessions. Parental contribution to endosperm gene dosage is somehow relaxed in triploids. Our Crataegus plant system resembles reproduction in the diploids and polyploids of North American hawthorns. Our data provide support for the hypothesis that polyploidization, shifts in reproduction modes, and hybridization shape the genus diversity also in Central Europe