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Jan Kirschner - One of the best experts on this subject based on the ideXlab platform.
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Taxonomic and nomenclatural notes on Juncus.
Preslia, 2020Co-Authors: Sven Snogerup, F. P. Zika, Jan KirschnerAbstract:New combinations and other nomenclatural notes on the Juncaceae (Juncus sections Iridifolii, Steirochloa and Juncotypus) are proposed within the framework of the preparation of the “Flora of the World” monograph of the family. New combinations are proposed in Juncus prismatocarpus, J. arcticus, J. balticus and J. effusus. On the basis of the new evaluation of Pacific North American plants examined by H. L. Lint in an unpublished thesis, two names are elevated to the species rank (J. hesperius and J. exiguus), and a new species is described (J. laccatus), all related to J. effusus.
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Typification of Juncus mutabilis Lam.
Taxon, 2009Co-Authors: Jan KirschnerAbstract:The protologue of the name Juncus mutabilis Lam. 1789 is analysed. Among twelve elements analysed (six specimens, six figures), ten represent original material from which a lectotype might be chosen. This material belongs to at least three taxa, Juncus capitatus, J. pygmaeus and J. bulbosus. A specimen deposited in P-LAM belonging to Juncus capitatus is selected as the lectotype, thus avoiding any changes of name.
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trnl trnf intergenic spacer and trnl intron define major clades within luzula and Juncus juncaceae importance of structural mutations
Journal of Molecular Evolution, 2004Co-Authors: Lenka Zaveska Drabkova, Jan Kirschner, Cestmir Vlcek, Vaclav PacesAbstract:Seven hundred fifty-two to one thousand ninety-seven base pairs of the trnL intron and trnL–trnF intergenic spacer of the chloroplast DNA of 55 Juncaceae taxa (Juncus, Luzula, Rostkovia, and Oxychloe) was sequenced. Seventeen structural mutations (13 indels marked A to M, 3 parts of the trnF pseudogene, and insertion “o” within a pseudogene) within the chloroplast trnL–trnF region were examined as possible indicators for phylogenetic relationships in Juncaceae. Juncus trifidus (section Steirochloa) was clearly separated from the other taxa by two large (>80 bp) indels. The “Southern Hemisphere clade” was strongly supported by a unique insertion (334 bp) in the trnL intron. The monophyly of Luzula was supported by three small (<10 bp) indels in the trnL-F spacer. They were found in all 22 examined members that represent the taxonomic and geographical diversity of the genus Luzula. A tandemly duplicated tRNA pseudogene was found in the Juncus subgenus Juncus species and is supported by four small unique indels too. The acceptor stem and D-domain-encoding regions are separated by a unique 8-bp insertion. The T-domain and acceptor stem-encoding regions were not found in the pseudogene repeats. Only the Juncus sections Ozophyllum and Iridifolii contain the 5′ acceptor stem, D-domain, and anticodon domain of the tRNAF encoding DNA. The structural mutations in the trnL intron and the trnL–trnF intergenic spacer are useful for phylogenetic reconstruction in the Juncaceae.
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TrnL–trnF Intergenic Spacer and trnL Intron Define Major Clades Within Luzula and Juncus (Juncaceae): Importance of Structural Mutations
Journal of Molecular Evolution, 2004Co-Authors: Lenka Drábková, Jan Kirschner, Čestmír Vlček, Vaclav PacesAbstract:Seven hundred fifty-two to one thousand ninety-seven base pairs of the trn L intron and trn L– trn F intergenic spacer of the chloroplast DNA of 55 Juncaceae taxa ( Juncus , Luzula , Rostkovia , and Oxychloë ) was sequenced. Seventeen structural mutations (13 indels marked A to M, 3 parts of the trn F pseudogene, and insertion “o” within a pseudogene) within the chloroplast trn L– trn F region were examined as possible indicators for phylogenetic relationships in Juncaceae. Juncus trifidus (section Steirochloa) was clearly separated from the other taxa by two large (>80 bp) indels. The “Southern Hemisphere clade” was strongly supported by a unique insertion (334 bp) in the trn L intron. The monophyly of Luzula was supported by three small (
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phylogeny of the juncaceae based on rbcl sequences with special emphasis on luzula dc and Juncus l
Plant Systematics and Evolution, 2003Co-Authors: Lenka Zaveska Drabkova, Jan Kirschner, Ole Seberg, Gitte Petersen, Cestmir VlcekAbstract:Cladistic analysis of rbcL nucleotide sequences was applied to 58 taxa representing most subgenera and sections of Luzula and Juncus, chosen to reflect morphological and geographical diversity of both genera. Addition- ally, representatives of all other genera of the Juncaceae and two taxa from the Cyperaceae were included. Phylogenetic trees were construct- ed using parsimony with Prionium serratum as outgroup. The dataset has 190 parsimony infor- mative sites. The analysis yielded more than 332,400 equally parsimonious trees (length 620, CI ¼ 0.47, RI ¼ 0.82). A jackknife analysis re- vealed several well-supported clades. Luzula is monophyletic and Juncus is non-monophyletic. Each of the generally accepted subgenera of Juncus, subg. Juncus and subg. Agathryon, form a clade, but their circumscription differs from the traditional views. The subgenera recognized in Luzula remain mainly unresolved. A well-sup- ported clade is represented by an assemblage of representatives of five genera and species distrib- uted in the Southern Hemisphere: Juncus capensis and J. lomatophyllus (both from section Gramini- folii), Rostkovia, Distichia, Marsippospermum, and Patosia.
Vaclav Paces - One of the best experts on this subject based on the ideXlab platform.
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trnl trnf intergenic spacer and trnl intron define major clades within luzula and Juncus juncaceae importance of structural mutations
Journal of Molecular Evolution, 2004Co-Authors: Lenka Zaveska Drabkova, Jan Kirschner, Cestmir Vlcek, Vaclav PacesAbstract:Seven hundred fifty-two to one thousand ninety-seven base pairs of the trnL intron and trnL–trnF intergenic spacer of the chloroplast DNA of 55 Juncaceae taxa (Juncus, Luzula, Rostkovia, and Oxychloe) was sequenced. Seventeen structural mutations (13 indels marked A to M, 3 parts of the trnF pseudogene, and insertion “o” within a pseudogene) within the chloroplast trnL–trnF region were examined as possible indicators for phylogenetic relationships in Juncaceae. Juncus trifidus (section Steirochloa) was clearly separated from the other taxa by two large (>80 bp) indels. The “Southern Hemisphere clade” was strongly supported by a unique insertion (334 bp) in the trnL intron. The monophyly of Luzula was supported by three small (<10 bp) indels in the trnL-F spacer. They were found in all 22 examined members that represent the taxonomic and geographical diversity of the genus Luzula. A tandemly duplicated tRNA pseudogene was found in the Juncus subgenus Juncus species and is supported by four small unique indels too. The acceptor stem and D-domain-encoding regions are separated by a unique 8-bp insertion. The T-domain and acceptor stem-encoding regions were not found in the pseudogene repeats. Only the Juncus sections Ozophyllum and Iridifolii contain the 5′ acceptor stem, D-domain, and anticodon domain of the tRNAF encoding DNA. The structural mutations in the trnL intron and the trnL–trnF intergenic spacer are useful for phylogenetic reconstruction in the Juncaceae.
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TrnL–trnF Intergenic Spacer and trnL Intron Define Major Clades Within Luzula and Juncus (Juncaceae): Importance of Structural Mutations
Journal of Molecular Evolution, 2004Co-Authors: Lenka Drábková, Jan Kirschner, Čestmír Vlček, Vaclav PacesAbstract:Seven hundred fifty-two to one thousand ninety-seven base pairs of the trn L intron and trn L– trn F intergenic spacer of the chloroplast DNA of 55 Juncaceae taxa ( Juncus , Luzula , Rostkovia , and Oxychloë ) was sequenced. Seventeen structural mutations (13 indels marked A to M, 3 parts of the trn F pseudogene, and insertion “o” within a pseudogene) within the chloroplast trn L– trn F region were examined as possible indicators for phylogenetic relationships in Juncaceae. Juncus trifidus (section Steirochloa) was clearly separated from the other taxa by two large (>80 bp) indels. The “Southern Hemisphere clade” was strongly supported by a unique insertion (334 bp) in the trn L intron. The monophyly of Luzula was supported by three small (
Mark Wagner - One of the best experts on this subject based on the ideXlab platform.
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influence of spartina and Juncus on saltmarsh sediments i pore water geochemistry
Chemical Geology, 2008Co-Authors: Carla M Koretsky, Melanie Haveman, Angel Cuellar, Lauren Beuving, Terri Shattuck, Mark WagnerAbstract:Abstract The influence of Spartina alterniflora and Juncus roemarianus on saltmarsh sediment pore water geochemistry was investigated during summer at four sites in a saltmarsh on Sapelo Island, GA, USA. Pore waters were collected from each site at 1–2 cm intervals, to a depth of 50 cm, and analyzed for pH, alkalinity, dissolved manganese, ferric iron, ferrous iron, total sulfide, sulfate, phosphate, ammonium, calcium, magnesium and potassium. The most compressed vertical redox stratification occurs at a short Spartina site, followed closely by an adjacent Juncus site. Both sites have shallow oxic and suboxic zones, with sulfidic conditions only a few centimeters or less from the sediment water interface. The densely vegetated Juncus site is inferred to have greater primary productivity and organic matter turnover compared to the short Spartina site. More radial oxygen loss is postulated to occur in the subsurface of the Juncus site, leading to reoxidation of reduced species, more acidic conditions and less accumulation of dissolved sulfide, ammonium and oxidizable-Fe in the solid phase compared to the adjacent short Spartina site. A creekside site vegetated by tall Spartina has the most oxidized sediments, followed by an adjacent unvegetated site. Both of these sites are dominated by suboxic pore waters in most of the upper 50 cm. Subsurface injection of oxygen via roots at the densely vegetated tall Spartina site is inferred to create more acidic pore waters with significantly less accumulation of reduced solutes, including ammonium and alkalinity, compared to the adjacent unvegetated creekside site. Fe and Mn reduction are expected to be significant processes in the bulk near-surface sediments of the tall Spartina and unvegetated sites and within rhizosphere sediments at the tall Spartina and Juncus sites. This study demonstrates the significant influence of Juncus roemarianus and Spartina alterniflora on saltmarsh sediment pore water geochemistry, with important implications for nutrient and trace metal mobility and bioavailability. Future work is needed to explore differences in organic matter concentration and especially lability in the subsurface of saltmarsh sites with varying types and densities of vegetation.
Carla M Koretsky - One of the best experts on this subject based on the ideXlab platform.
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influence of spartina and Juncus on saltmarsh sediments i pore water geochemistry
Chemical Geology, 2008Co-Authors: Carla M Koretsky, Melanie Haveman, Angel Cuellar, Lauren Beuving, Terri Shattuck, Mark WagnerAbstract:Abstract The influence of Spartina alterniflora and Juncus roemarianus on saltmarsh sediment pore water geochemistry was investigated during summer at four sites in a saltmarsh on Sapelo Island, GA, USA. Pore waters were collected from each site at 1–2 cm intervals, to a depth of 50 cm, and analyzed for pH, alkalinity, dissolved manganese, ferric iron, ferrous iron, total sulfide, sulfate, phosphate, ammonium, calcium, magnesium and potassium. The most compressed vertical redox stratification occurs at a short Spartina site, followed closely by an adjacent Juncus site. Both sites have shallow oxic and suboxic zones, with sulfidic conditions only a few centimeters or less from the sediment water interface. The densely vegetated Juncus site is inferred to have greater primary productivity and organic matter turnover compared to the short Spartina site. More radial oxygen loss is postulated to occur in the subsurface of the Juncus site, leading to reoxidation of reduced species, more acidic conditions and less accumulation of dissolved sulfide, ammonium and oxidizable-Fe in the solid phase compared to the adjacent short Spartina site. A creekside site vegetated by tall Spartina has the most oxidized sediments, followed by an adjacent unvegetated site. Both of these sites are dominated by suboxic pore waters in most of the upper 50 cm. Subsurface injection of oxygen via roots at the densely vegetated tall Spartina site is inferred to create more acidic pore waters with significantly less accumulation of reduced solutes, including ammonium and alkalinity, compared to the adjacent unvegetated creekside site. Fe and Mn reduction are expected to be significant processes in the bulk near-surface sediments of the tall Spartina and unvegetated sites and within rhizosphere sediments at the tall Spartina and Juncus sites. This study demonstrates the significant influence of Juncus roemarianus and Spartina alterniflora on saltmarsh sediment pore water geochemistry, with important implications for nutrient and trace metal mobility and bioavailability. Future work is needed to explore differences in organic matter concentration and especially lability in the subsurface of saltmarsh sites with varying types and densities of vegetation.
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Seasonal Influence of the Needle Rush Juncus roemarianus on Saltmarsh Pore Water Geochemistry
Estuaries and Coasts, 2007Co-Authors: Carla M Koretsky, Douglas MillerAbstract:Previous studies have shown that saltmarsh macrophytes have a significant influence on sediment biogeochemistry, both through radial release of oxygen from roots and also via primary production and release of labile organic exudates from roots. To assess the seasonal influence of the needle rush, Juncus roemarianus, on saltmarsh sediment geochemistry, pore waters and sediments were collected from the upper 50 cm of two adjacent sites, one unvegetated and the other vegetated by Juncus roemarianus, in a Georgia saltmarsh during winter and summer. Pore waters collected at 1- to 2-cm intervals were analyzed for pH, alkalinity, dissolved phosphate, ammonium, Fe(II), Fe(III), Mn(II), sulfide, sulfate, and organic carbon. Sediments were collected at 5-cm intervals and analyzed for iron distribution in the solid phase using a two-step sequential extraction. The upper 50 cm of the sediment pore waters are mostly sulfidic during both winter and summer. The pore water and sediment geochemistry suggest organic matter degradation is coupled mostly to Fe(III) and sulfate reduction. In summer, there is greater accumulation of alkalinity, sulfide, ammonium, and phosphate in the pore waters and lower levels of ascorbate extractable Fe, which is presumed to be comprised primarily of readily reducible Fe(III) oxides, in the sediments, consistent with higher organic matter degradation rates in summer compared to winter. Lower pH, alkalinity, ammonium, and sulfide concentrations in sediments with Juncus, compared to nearby unvegetated sediments, is consistent with release of oxygen into the Juncus rhizosphere, especially during summer.
Oscar Vicente - One of the best experts on this subject based on the ideXlab platform.
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stress tolerance mechanisms in Juncus responses to salinity and drought in three Juncus species adapted to different natural environments
Functional Plant Biology, 2016Co-Authors: Mohamad Al Hassan, Maria Pilar Lopezgresa, Monica Boscaiu, Oscar VicenteAbstract:Comparative studies on the responses to salinity and drought were carried out in three Juncus species, two halophytes (Juncus maritimus Lam. and Juncus acutus L.) and one more salt-sensitive (Juncus articulatus L.). Salt tolerance in Juncus depends on the inhibition of transport of toxic ions to the aerial part. In the three taxa studied Na+ and Cl– accumulated to the same extent in the roots of salt treated plants; however, ion contents were lower in the shoots and correlated with the relative salt sensitivity of the species, with the lowest levels measured in the halophytes. Activation of K+ transport at high salt concentration could also contribute to salt tolerance in the halophytes. Maintenance of cellular osmotic balance is mostly based on the accumulation of sucrose in the three species. Yet, neither the relative salt-induced increase in sugar content nor the absolute concentrations reached can explain the observed differences in salt tolerance. In contrast, proline increased significantly in the presence of salt only in the salt-tolerant J. maritimus and J. acutus, but not in J. articulatus. Similar patterns of osmolyte accumulation were observed in response to water stress, supporting a functional role of proline in stress tolerance mechanisms in Juncus.
