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  • 301. Ilina, Elena L.
    et al.
    Logachov, Anton A.
    Laplaze, Laurent
    Demchenko, Nikolay P.
    Pawlowski, Katharina
    Stockholm University, Faculty of Science, Department of Botany.
    Demchenko, Kirill N.
    Composite Cucurbita pepo plants with transgenic roots as a tool to study root development2012In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 110, no 2, p. 479-489Article in journal (Refereed)
    Abstract [en]

    In most plant species, initiation of lateral root primordia occurs above the elongation zone. However, in cucurbits and some other species, lateral root primordia initiation and development takes place in the apical meristem of the parental root. Composite transgenic plants obtained by Agrobacterium rhizogenes-mediated transformation are known as a suitable model to study root development. The aim of the present study was to establish this transformation technique for squash. The auxin-responsive promoter DR5 was cloned into the binary vectors pKGW-RR-MGW and pMDC162-GFP. Incorporation of 5-ethynyl-2-deoxyuridine (EdU) was used to evaluate the presence of DNA-synthesizing cells in the hypocotyl of squash seedlings to find out whether they were suitable for infection. Two A. rhizogenes strains, R1000 and MSU440, were used. Roots containing the respective constructs were selected based on DsRED1 or green fluorescent protein (GFP) fluorescence, and DR5::Egfp-gusA or DR5::gusA insertion, respectively, was verified by PCR. Distribution of the response to auxin was visualized by GFP fluorescence or -glucuronidase (GUS) activity staining and confirmed by immunolocalization of GFP and GUS proteins, respectively. Based on the distribution of EdU-labelled cells, it was determined that 6-day-old squash seedlings were suited for inoculation by A. rhizogenes since their root pericycle and the adjacent layers contain enough proliferating cells. Agrobacterium rhizogenes R1000 proved to be the most virulent strain on squash seedlings. Squash roots containing the respective constructs did not exhibit the hairy root phenotype and were morphologically and structurally similar to wild-type roots. The auxin response pattern in the root apex of squash resembled that in arabidopsis roots. Composite squash plants obtained by A. rhizogenes-mediated transformation are a good tool for the investigation of root apical meristem development and root branching.

  • 302.
    Ininbergs, Karolina
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Bay, Guillaume
    Stockholm University, Faculty of Science, Department of Botany.
    Rasmussen, Ulla
    Stockholm University, Faculty of Science, Department of Botany.
    Wardle, David A.
    Nilsson, Marie-Charlotte
    Composition and diversity of nifH genes of nitrogen-fixing cyanobacteria associated with boreal forest feather mosses2011In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 192, no 2, p. 507-517Article in journal (Refereed)
    Abstract [en]

    Recent studies have revealed that nitrogen fixation by cyanobacteria living in association with feather mosses is a major input of nitrogen to boreal forests. We characterized the community composition and diversity of cyanobacterial nifH phylotypes associated with each of two feather moss species (Pleurozium schreberi and Hylocomium splendens) on each of 30 lake islands varying in ecosystem properties in northern Sweden. Nitrogen fixation was measured using acetylene reduction, and nifH sequences were amplified using general and cyanobacterial selective primers, separated and analyzed using density gradient gel electrophoresis (DGGE) or cloning, and further sequenced for phylogenetic analyses. Analyses of DGGE fingerprinting patterns revealed two host-specific clusters (one for each moss species), and sequence analysis showed five clusters of nifH phylotypes originating from heterocystous cyanobacteria. For H. splendens only, N(2) fixation was related to both nifH composition and diversity among islands. We demonstrated that the cyanobacterial communities associated with feather mosses show a high degree of host specificity. However, phylotype composition and diversity, and nitrogen fixation, did not differ among groups of islands that varied greatly in their availability of resources. These results suggest that moss species identity, but not extrinsic environmental conditions, serves as the primary determinant of nitrogen-fixing cyanobacterial communities that inhabit mosses.

  • 303.
    Isaeus, Martin
    Stockholm University, Faculty of Science, Department of Botany.
    A GIS-based wave exposure model calibrated and validated from vertical distribution of littoral lichensManuscript (Other academic)
  • 304.
    Isaeus, Martin
    Stockholm University, Faculty of Science, Department of Botany.
    Factors structuring Fucus communities at open and complex coastlines in the Baltic Sea2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with physical factors and biological interactions affecting the distribution of two fucoid species, Fucus vesiculosus and F. serratus, in the Baltic Sea. Studies have been carried out in two quite different environments: an archipelago, and an open rocky coast. The archipelago has an extremely long coastline with a heterogeneous submerged landscape of different substrate types, slopes, water qualities, and degrees of wave exposure. The factors influencing F. vesiculosus distribution, morphology and epiphyte composition were studied in the Stockholm archipelago using field surveys and spatial modelling in Geographic information systems (GIS). A GIS-method to estimate wave exposure was developed and validated by comparing the result to an index based on vertical zonation of lichens. Wave exposure was considered an important factor for predicting the distribution of F. vesiculosus by its ability to clean hard surfaces from silt, and a predictive model was constructed based on the information of wave exposure and slope of the shore. It is suggested that the lower distribution boundary of attached F. vesiculosus is set by sediment in sheltered parts of the archipelago, and by light availability in highly wave exposed parts. The morphology of F. vesiculosus was studied over a wave exposure gradient, and several characters responded in accordance with earlier studies. However, when separating effects of wave exposure from effects of other confounding water property parameters, only thallus width was significantly different. Several water property parameters were shown to be correlated with wave exposure in the Stockholm archipelago, and the mechanism responsible for the effects on F. vesiculosus morphology is discussed. The composition of epiphytes on F. vesiculosus varied over a wave exposure gradient with a positive correlation to Elachista fucicola, and a negative to Chorda filum.

    At an open coast the physical environment is much less heterogeneous compared to an archipelago. The distributions of F. vesiculosus, F. serratus, turf-forming algae, and the seafloor substrate, were surveyed along the open coasts of Öland and Gotland. Turf-forming algae dominated all hard substrates in the area, and Polysiphonia fucoides was most abundant. At the Gotland coast F. vesiculosus was less abundant than at the Öland coast, and F. serratus occurred only in the southern-most part. Fucus serratus was increasingly more common towards south which was interpreted as an effect mainly of the Baltic salinity gradient, or the variation of salinity that has occurred in the past. The effects of turf-forming algae and sediment on F. serratus recruitment at 7 m depth off the Öland east coast were studied in the field, and by laboratory experiments. Almost no recruits were found in the algal turf outside the F. serratus patches. More fine sediment was found in the turf than in the F. serratus patches, suggesting that the turf accumulates sediment by decreasing resuspension. Both filamentous algae and sediment decreased the attachment ability of F. serratus zygotes and survival of recruits, and sediment had the strongest effect. It is therefore suggested that F. serratus has difficulties recruiting outside its patches, and that these difficulties are enforced by the eutrophication of the Baltic Sea, which has favoured growth of filamentous algae and increased sedimentation. An overall conclusion is that Fucus distribution is affected by large-scale-factors, such as the eutrophication and salinity changes of the Baltic Sea, as well as by small-scale variation in wave exposure, substrate and slope, and by surface competition with neighbouring species.

  • 305.
    Isaeus, Martin
    Stockholm University, Faculty of Science, Department of Botany.
    Morphological variation of Fucus vesiculosus caused by wave action, or by factors correlated to waves?Manuscript (Other academic)
  • 306.
    Isaeus, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Lindblad, C
    A predictive GIS model using factors structuring Fucus vesiculosus distribution in a Baltic Sea archipelagoIn: Estuarine, Coastal and Shelf Science, ISSN 0272-7714Article in journal (Refereed)
  • 307.
    Isaeus, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Malm, T
    Effects of salinity and geomorphology on the structure of macroalgal communities in the central Baltic SeaIn: Annales Botanici Fennici, ISSN 0003-3847Article in journal (Refereed)
  • 308.
    Isaeus, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Malm, T
    Persson, S
    Svensson, A
    Effects of filamentous algae and sediment on recruitment and survival of Fucus vesiculosus (Phaeophyceae) juveniles in the eutrophic Baltic SeaIn: European Journal of Phycology, ISSN 0967-0262Article in journal (Refereed)
  • 309. Iversen, Morten Hvitfeldt
    et al.
    Nowald, Nicolas
    Ploug, Helle
    Stockholm University, Faculty of Science, Department of Botany.
    Jackson, George A.
    Fischer, Gerhard
    High resolution profiles of vertical particulate organic matter export off Cape Blanc, Mauritania: Degradation processes and ballasting effects2010In: Deep Sea Research Part I: Oceanographic Research Papers, ISSN 0967-0637, E-ISSN 1879-0119, Vol. 57, no 6, p. 771-784Article in journal (Refereed)
    Abstract [en]

    Vertical carbon fluxes between the surface and 2500 m depth were estimated from in situ profiles of particle size distributions and abundances me/asured off Cape Blanc (Mauritania) related to deep ocean sediment traps. Vertical mass fluxes off Cape Blanc were significantly higher than recent global estimates in the open ocean. The aggregates off Cape Blanc contained high amounts of ballast material due to the presence of coccoliths and fine-grained dust from the Sahara desert, leading to a dominance of small and fast-settling aggregates. The largest changes in vertical fluxes were observed in the surface waters (<250 m), and, thus, showing this site to be the most important zone for aggregate formation and degradation. The degradation length scale (L), i.e. the fractional degradation of aggregates per meter settled, was estimated from vertical fluxes derived from the particle size distribution through the water column. This was compared with fractional remineralization rate of aggregates per meter settled derived from direct ship-board measurements of sinking velocity and small-scale 02 fluxes to aggregates measured by micro-sensors. Microbial respiration by attached bacteria alone could not explain the degradation of organic matter in the upper ocean. Instead, flux feeding from zooplankton organisms was indicated as the dominant degradation process of aggregated carbon in the surface ocean. Below the surface ocean, microbes became more important for the degradation as zooplankton was rare at these depths.

  • 310.
    Jakobsson, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Padron, Benigno
    Traveset, Anna
    Pollen transfer from invasive Carpobrotus spp. to natives: A study of pollinator behaviour and reproduction success2008In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 141, no 1, p. 136-145Article in journal (Refereed)
    Abstract [en]

    The influence of invasive plant species on native community composition is well-documented, but less is known about underlying mechanisms. Especially scarce is knowledge about effects on biotic interactions such as relationships between native plants and their pollinators. In this study we investigate if pollen transfer from the invasive and highly pollen productive Carpobrotus spp. affects seed production and/or seed quality in three native species. We monitored pollinator movements and pollen loads on pollinators and native stigmas, and in a field pollination experiment we investigated the effect of invasive pollen on reproduction. Invasive pollen adhered to pollinators, pollinators switched from Carpobrotus spp. to natives, invasive pollen was transferred to native stigmas, and it affected seed production in one species. Although all possible steps for interference with seed production were found to be qualitatively taken, invasive pollen has probably little impact on the native community because the frequency of invasive pollen transfer to natives was low. However, pollination interactions may change with plant abundance and our study provides evidence that pollen transfer from Carpobrotus spp. to natives does occur and have the potential to affect seed production. We found the species identity of shared pollinators to be of importance, higher flower constancy and lower capacity of pollen adherence are likely to result in less invasive pollen transfer. 

  • 311. Janhunen, Pekka
    et al.
    Kaartokallio, Hermanni
    Oksanen, Ilona
    Stockholm University, Faculty of Science, Department of Botany.
    Lehto, Kirsi
    Lehto, Harry
    Biological Feedbacks as Cause and Demise of Neoproterozoic Icehouse: Astrobiological Prospects for Faster Evolution and Importance of Cold Conditions2007In: PLOS ONE, ISSN 1932-6203, Vol. 2, no 2, p. e214-Article in journal (Refereed)
    Abstract [en]

    Several severe glaciations occurred during the Neoproterozoic eon, and especially near its end in the Cryogenian period (630-850 Ma). While the glacial periods themselves were probably related to the continental positions being appropriate for glaciation, the general coldness of the Neoproterozoic and Cryogenian as a whole lacks specific explanation. The Cryogenian was immediately followed by the Ediacaran biota and Cambrian Metazoan, thus understanding the climate-biosphere interactions around the Cryogenian period is central to understanding the development of complex multicellular life in general. Here we present a feedback mechanism between growth of eukaryotic algal phytoplankton and climate which explains how the Earth system gradually entered the Cryogenian icehouse from the warm Mesoproterozoic greenhouse. The more abrupt termination of the Cryogenian is explained by the increase in gaseous carbon release caused by the more complex planktonic and benthic foodwebs and enhanced by a diversification of metazoan zooplankton and benthic animals. The increased ecosystem complexity caused a decrease in organic carbon burial rate, breaking the algal-climatic feedback loop of the earlier Neoproterozoic eon. Prior to the Neoproterozoic eon, eukaryotic evolution took place in a slow timescale regulated by interior cooling of the Earth and solar brightening. Evolution could have proceeded faster had these geophysical processes been faster. Thus, complex life could theoretically also be found around stars that are more massive than the Sun and have main sequence life shorter than 10 Ga. We also suggest that snow and glaciers are, in a statistical sense, important markers for conditions that may possibly promote the development of complex life on extrasolar planets.

  • 312.
    Javed, M. Tariq
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Stoltz, Eva
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany.
    Greger, Maria
    Changes in pH and organic acids in mucilage of Eriophorum angustifolium roots after exposure to elevated concentrations of toxic elements2012In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 20, no 3, p. 1876-1880Article in journal (Refereed)
    Abstract [en]

    The presence of Eriophorum angustifolium in mine tailings of pyrite maintains a neutral pH, despite weathering, thus lowering the release of toxic elements into acid mine drainage water. We investigated if the presence of slightly elevated levels of free toxic elements triggers the plant rhizosphere to change the pH towards neutral by increasing organic acid content. Plants were treated with a combination of As, Pb, Cu, Cd and Zn at different concentrations in nutrient medium and in soil in a rhizobox-like system for 48-120 hrs. The pH and organic acids were detected in the mucilage dissolved from root surface, reflecting the rhizosphere solution. Also the pH of root-cell apoplasm was investigated. Both apoplasmic and mucilage pH increased and the concentrations of organic acids enhanced in the mucilage with slightly elevated levels of toxic elements. When organic acid concentration was high, also the pH was high. Thus, efflux of organic acids from the roots of E. angustifolium may induce rhizosphere basification.

  • 313.
    Javed, Muhammad Tariq
    Stockholm University, Faculty of Science, Department of Botany.
    Mechanisms behind pH changes by plant roots and shoots caused by elevated concentration of toxic elements2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Toxic elements are present in polluted water from mines, industrial outlets, storm water etc. Wetland plants take up toxic elements and increase the pH of the medium. In this thesis was investigated how the shoots of submerged plants and roots of emergent plants affected the pH of the surrounding water in the presence of free toxic ions. The aim was to clarify the mechanisms by which these plants change the surrounding water pH in the presence of toxic ions.

    The influence of Elodea canadensis shoots on the pH of the surrounding water was studied in the presence of cadmium (Cd) at low initial pH (4-5). The involvement of photosynthetic activity in the pH changes was investigated in the presence and absence of Cd. The cytosolic, vacuolar and apoplasmic pH changes as well as cytosolic Cd changes in E. canadensis were monitored. The influence of Eriophorum angustifolium roots on the pH of the surrounding water was investigated in the presence of a combination of Cd, copper, lead, zinc and arsenic at low initial pH (3.5). Eriophorum angustifolium root exudates were analyzed for organic acids.

    Elodea canadensis shoots increased the pH of the surrounding water, an effect more pronounced with increasing Cd levels and/or increasing plant biomass and increased plant Cd uptake. The pH increase in the presence of free Cd ions was not due to photosynthesis or proton uptake across the plasmalemma or tonoplast. Cadmium was initially sequestered in the apoplasm of E. canadensis and caused its acidosis. Eriophorum angustifolium roots increased the surrounding water pH and this effect was enhanced in the presence of arsenic and metals. This pH increase was found to depend partly on the release of oxalic acid, formic acid and succinic acid by the plants.

    In conclusion, E. canadensis shoots and E. angustifolium roots were found to increase the low initial pH of the surrounding water. The pH modulation by these species was enhanced by low levels of free toxic ions in the surrounding water.

  • 314.
    Javed, Muhammad Tariq
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Greger, Maria
    Stockholm University, Faculty of Science, Department of Botany.
    Cadmium triggers Elodea canadensis to change the surrounding water pH and thereby Cd uptake2011In: International journal of phytoremediation, ISSN 1522-6514, E-ISSN 1549-7879, Vol. 13, no 1, p. 95-106Article in journal (Refereed)
    Abstract [en]

    This study was aimed to investigate the influence of Elodea canadensis shoots on surrounding water pH in the presence of cadmium and the effect of plant-induced pH on cadmium uptake. The pH change in the surrounding nutrient solution and Cd uptake by Elodea shoots were investigated after cultivation of various plant densities (1, 3, 6 plants per 500 ml) in hydroponics at a starting pH of 4.0 and in the presence of different concentrations of cadmium (0, 0.1, 0.5 µM). Cadmium uptake was also investigated at different constant pH (4.0, 4.5, 5.5 and 6.5). To investigate if the pH change arose from photosynthetic activities, plants were grown under light, darkness or in the presence of a photosynthetic inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and 0.5 µM cadmium in the solution. Elodea had an ability to increase the surrounding water pH, when the initial pH was low, which resulted in increased accumulation of Cd. The higher the plant density, the more pronounced was the pH change. The pH increase was not due to the photosynthetic activity since the pH rise was more pronounced under darkness and in the presence of DCMU. The pH increase by Elodea was triggered by cadmium.

  • 315.
    Javed, Muhammad Tariq
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany.
    Greger, Maria
    Stockholm University, Faculty of Science, Department of Botany.
    Cytosolic uptake of cadmium causes an extra- and intra-cellular basification in Elodea canadensisManuscript (preprint) (Other academic)
    Abstract [en]

    The current study was aimed to investigate the pH changes by Elodea canadensis shoots under different photosynthetic conditions in the presence and absence of cadmium (Cd) and its influence on Cd uptake. Plants were grown under light, dark and in the presence of the photosynthetic inhibitor (3-(3,4-dichlorophenyl)-1,1-dimethylurea) with and without 0.5 µM Cd in the solution at a starting pH of 5.0. The Cd uptake into the cytosol of leaf protoplasts was investigated by using a Cd-specific fluorescent dye, LeadmiumTM Green AM. Cadmium and proton dynamics were monitored in leaf protoplasts after plant exposure to 0.5 µM CdCl2 for 3 and 7 d, respectively. The pH sensitive dye BCECF-AM was used to detect cytosolic pH changes. The shoots increased the surrounding water pH, which enhanced Cd uptake. Beside pH increase by photosynthetic activity, E. canadensis possessed additional mechanisms to raise the surrounding water pH in the presence of Cd. The cytosolic cadmium (Cd2+cyt) fluorescence of leaf protoplasts increased upon addition of CdCl2 to the external medium, reflecting (Cd2+cyt) uptake. Plant exposure to 0.5 µM CdCl2 for 3 d did not induce significant changes in (Cd2+cyt)and [pH]cyt. However, the (Cd2+cyt) and pHcyt were significantly increased after plant exposure to 0.5 µM CdCl2 for 7d. This suggests that E. canadensis initially sequester Cd in its apoplasmic region depending upon the presence of acidic polysaccharides in its cell wall and external medium basification. With time Cd translocates into the cytosol and subsequently causes its basification.

  • 316.
    Javed, Muhammad Tariq
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany.
    Maria, Greger
    Stockholm University, Faculty of Science, Department of Botany.
    Cadmium induces cellular pH changes in Elodea canadensis and causes external basificationArticle in journal (Refereed)
    Abstract [en]

    Earlier investigations showed that Elodea canadensis causes a basification of the surrounding medium in the presence of cadmium. This study was aimed to investigate the mechanism by which Cd causes this plant to increase the surrounding water pH. Cd-induced pH changes in cytosol, vacuole and apoplastic regions of E. canadensis were monitored by fluorescence microscopy and pH-specific fluorescent dyes. Since cytosolic Ca2+ and pH homeostasis are closely linked, the cytosolic calcium [Ca2+]cytwas also investigated after Cd treatment. Cd binding to the cell walls of E. canadensis was investigated after cultivation of plants at different fixed pH. We developed a new enzymatic method for the isolation of protoplasts from E. canadensis leaves. Cd exposure resulted in a subsequent increase in both cytosolic and vacuolar pH of leaf protoplasts and concomitant rise in the [Ca2+]cyt. Changes in [Ca2+]cyt and [pH]cyt followed the same dynamics upon Cd addition, but the changes in [pH]cyt seemed to be prior to the [Ca2+]cyt changes. Cd treatment decreased the apoplastic pH by 0.85 units and Cd contents of cell walls were enhanced at low pH. In conclusion, Cd exposure decreased the apoplastic pH of E. canadensis and resulted in Cd binding to the cell walls which may prevent Cd influx to the cytosol. The results suggest that the Cd-induced apoplastic acidification can be one of the mechanisms to increase the surrounding medium pH by E. canadensis shoots.

  • 317.
    Javed, Muhammad Tariq
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Stoltz, Eva
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany.
    Greger, Maria
    Stockholm University, Faculty of Science, Department of Botany.
    pH changes and organic acids exudation by Eriophorum angustifolium roots exposed to elevated concentration of toxic elementsArticle in journal (Refereed)
    Abstract [en]

    This study was aimed to investigate the influence of Eriophorum angustifolium roots on surrounding water pH in the presence of heavy metals and As, and the possible mechanism behind. We monitored the pH in the surrounding nutrient solution by E. angustifolium roots at a starting pH 3.5 and in the presence of a combination of As, Pb, Cu, Cd and Zn at different concentrations. The metal and As contents in the plant shoots and roots were analyzed as well as organic acids in the root exudates. Fluorescence microscopy and a pH-specific fluorescent dye were used to investigate the influence of different elements on apoplastic pH of E. angustifolium roots. The results showed that the roots have the ability to increase the rhizosphere pH even in the presence of different free metal ions and As. The plant root metal and As contents were significantly higher as compared with shoots. Metal and As treatment at higher concentrations significantly caused the apoplastic pH to increase in this species. Of the acids analyzed, the exudation of the oxalic, formic and succinic acids was significantly enhanced after metal and As exposure, as compared with control, giving the maximum concentration of these acids after 25 µM As, Cu, Zn, Pb and 2.5 µM Cd treatment. The roots of E. angustifolium respond to toxic ions by releasing organic acids, which transiently induce rhizosphere basification.

  • 318. Johannesson, Kerstin
    et al.
    Forslund, Helena
    Stockholm University, Faculty of Science, Department of Botany.
    Åstrand Capetillo, Nastassja
    Stockholm University, Faculty of Science, Department of Botany.
    Kautsky, Lena
    Stockholm University, Faculty of Science, Department of Botany.
    Johansson, Daniel
    Pereyra, Ricardo T.
    Råberg, Sonja
    Stockholm University, Faculty of Science, Department of Botany.
    Phenotypic variation in sexually and asexually recruited individuals of the Baltic Sea endemic macroalga Fucus radicans: in the field and after growth in a common-garden2012In: BMC Ecology, ISSN 1472-6785, E-ISSN 1472-6785, Vol. 12, p. 2-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Most species of brown macroalgae recruit exclusively sexually. However, Fucus radicans, a dominant species in the northern Baltic Sea, recruits new attached thalli both sexually and asexually. The level of asexual recruitment varies among populations from complete sexual recruitment to almost (> 90%) monoclonal populations. If phenotypic traits have substantial inherited variation, low levels of sexual activity will decrease population variation in these traits, which may affect function and resilience of the species. We assessed the level of inherited variation in nine phenotypic traits by comparing variation within and among three monoclonal groups and one group of unique multilocus genotypes (MLGs) sampled in the wild.

    RESULTS: Of the nine phenotypic traits, recovery after freezing, recovery after desiccation, and phlorotannin content showed substantial inherited variation, that is, phenotypic variation in these traits were to a large extend genetically determined. In contrast, variation in six other phenotypic traits (growth rate, palatability to isopod grazers, thallus width, distance between dichotomies, water content after desiccation and photochemical yield under ambient conditions) did not show significant signals of genetic variation at the power of analyses used in the study. Averaged over all nine traits, phenotypic variation within monoclonal groups was only 68% of the variation within the group of different MLGs showing that genotype diversity does affect the overall level of phenotypic variation in this species.

    CONCLUSIONS: Our result indicates that, in general, phenotypic diversity in populations of Fucus radicans increases with increased multilocus genotype (MLG) diversity, but effects are specific for individual traits. In the light of Fucus radicans being a foundation species of the northern Baltic Sea, we propose that increased MLG diversity (leading to increased trait variation) will promote ecosystem function and resilience in areas where F. radicans is common, but this suggestion needs experimental support.

  • 319. Johannesson, Kerstin
    et al.
    Johansson, Daniel
    Larsson, Karl H.
    Huenchunir, Cecilia J.
    Perus, Jens
    Forslund, Helena
    Stockholm University, Faculty of Science, Department of Botany.
    Kautsky, Lena
    Stockholm University, Faculty of Science, Department of Botany.
    Pereyra, Ricardo T.
    FREQUENT CLONALITY IN FUCOIDS (FUCUS RADICANS AND FUCUS VESICULOSUS; FUCALES, PHAEOPHYCEAE) IN THE BALTIC SEA2011In: Journal of Phycology, ISSN 0022-3646, E-ISSN 1529-8817, Vol. 47, no 5, p. 990-998Article in journal (Refereed)
    Abstract [en]

    Asexual reproduction by cloning may affect the genetic structure of populations, their potential to evolve, and, among foundation species, contributions to ecosystem functions. Macroalgae of the genus Fucus are known to produce attached plants only by sexual recruitment. Recently, however, clones of attached plants recruited by asexual reproduction were observed in a few populations of Fucus radicans Bergstrom et L. Kautsky and F. vesiculosus L. inside the Baltic Sea. Herein we assess the distribution and prevalence of clonality in Baltic fucoids using nine polymorphic microsatellite loci and samples of F. radicans and F. vesiculosus from 13 Baltic sites. Clonality was more common in F. radicans than in F. vesiculosus, and in both species it tended to be most common in northern Baltic sites, although variation among close populations was sometimes extensive. Individual clonal lineages were mostly restricted to single or nearby locations, but one clonal lineage of F. radicans dominated five of 10 populations and was widely distributed over 550 x 100 km of coast. Populations dominated by a few clonal lineages were common in F. radicans, and these were less genetically variable than in other populations. As thalli recruited by cloning produced gametes, a possible explanation for this reduced genetic variation is that dominance of one or a few clonal lineages biases the gamete pool resulting in a decreased effective population size and thereby loss of genetic variation by genetic drift. Baltic fucoids are important habitat-forming species, and genetic structure and presence of clonality have implications for conservation strategies.

  • 320.
    Johansson, Lena
    Stockholm University, Faculty of Science, Department of Botany.
    Population dynamics of Gentianella campestris, effects of grassland management, soil conditions and the history of the landscape2007Book (Other academic)
  • 321.
    Johansson, Veronika A.
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Remnant Populations and Plant Functional Traits in Abandoned Semi-Natural Grasslands2011In: Folia Geobotanica, ISSN 1211-9520, E-ISSN 1874-9348, Vol. 46, no 2-3, p. 165-179Article in journal (Refereed)
    Abstract [en]

    Although semi-natural grasslands in Europe are declining there is often a time delay in the local extinction of grassland species due to development of remnant populations, i.e., populations with an extended persistence despite a negative growth rate. The objectives of this study were to examine the occurrence of remnant populations after abandonment of semi-natural grasslands and to examine functional traits of plants associated with the development of remnant populations. We surveyed six managed semi-natural grasslands and 20 former semi-natural grasslands where management ceased 60-100 years ago, and assessed species response to abandonment, assuming a space-for-time substitution. The response of species was related to nine traits representing life cycle, clonality, leaf traits, seed dispersal and seed mass. Of the 67 species for which data allowed analysis, 44 species declined after grassland abandonment but still occurred at the sites, probably as remnant populations. Five traits were associated with the response to abandonment. The declining but still occurring species were characterized by high plant height, a perennial life form, possession of a perennial bud bank, high clonal ability, and lack of dispersal attributes promoting long-distance dispersal. Traits allowing plants to maintain populations by utilizing only a part of their life cycle, such as clonal propagation, are most important for the capacity to develop remnant populations and delay local extinction. A considerable fraction of the species inhabiting semi-natural grasslands maintain what is most likely remnant populations after more than 60 years of spontaneous succession from managed semi-natural grasslands to forest.

  • 322.
    Johnson, Samuel
    Stockholm University, Faculty of Science, Department of Botany.
    The response of bryophytes to wildfire: To what extent do they survive in situ?2007Book (Other academic)
  • 323.
    Jonasson, Sara
    Stockholm University, Faculty of Science, Department of Botany.
    Monitoring the cellular phosphate status in bloom-forming cyanobacteria of the Baltic Sea2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the Baltic Sea dense cyanobacterial blooms occur regularly during late summer. Since the dominant bloom-forming cyanobacteria, Nodularia spp. and Apanizomenon spp. are capable of fixing atmospheric dinitrogen, the macronutrient predominantly limiting their growth is phosphorus. The main aim of this thesis was to develop molecular tools for monitoring the cellular P status in bloom-forming cyanobacteria in Baltic Sea. In this thesis I describe the development and the use of competitive RT-PCR, Pyrosequencing and Real-time PCR technology for determination of mRNA levels of two cyanobacterial pstS gene copies, encoding proteins involved in phosphate uptake. I have also studied the expression of three other typical P-stress induced genes involved in assimilation (phoA) and storage (ppk and ppx) of phosphate, using Real-time PCR. The model system used was laboratory cultures of Anabaena 7120 and Nodularia spumigena. The method was then implemented on field samples collected from the Baltic Sea during the summer of 2005.

    The gene expressions of the two pstS genes showed satisfied response to varied Pi levels and were induced simultaneously while the three other genes investigated did not solely respond to depleting Pi concentration. The two pstS genes are therefore more suitable for indicators of Pi stress. The phoA gene was continuously expressed while the ppk gene and the ppx gene responded to varied Pi levels, but their expressions are dependent on the cell capacity for phosphate storage, which may differ from one cell to another.

    This thesis also includes method development and analysis of the expression of the nda gene cluster, encoding the toxic compound nodularin, which is produced by Nodularia spumigena. During Pi depletion the gene expression increased while gene expression decreased during N supplementation. The results also suggests that cells keep a certain amount of nodularin inside the cell, and concentrations above this threshold level will either be degraded intracellulary or transported out of the cell.

  • 324.
    Jonasson, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Berntzon, Lotta
    Stockholm University, Faculty of Science, Department of Botany.
    Rasmussen, Ulla
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    A novel cyanobacterial toxin (BMAA) with potential neurodegenerative effects2008In: Plant Biotechnology, ISSN 1342-4580, E-ISSN 1347-6114, Vol. 25, no 3, p. 227-232Article in journal (Refereed)
    Abstract [en]

    The non-protein amino acid beta-N-methyl-amino-L-alanine (BMAA) is a neurotoxin that was recently found to be produced by most cyanobacteria. The neurotoxin was discovered in 1967 in the seeds of the cycad Cycas micronesica, but this BMAA may originate from the symbiotic cyanobacterium Nostoc, which inhabits the roots of cycads. BMAA is thought to be the cause of the deadly neurodegenerative disease amyotrophic lateral sclerosis/parkinsonism dementia complex (ALS/PDC), common among the Chamorro people of Guam. It was demonstrated that the Chamorros, in all probability, have been exposed to high levels of BMAA through dietary consumption of flying foxes which fed mainly on cycads seeds. BMAA production may be a common conserved evolutionary feature among cyanobacteria and due to their wide global distribution, the toxin may be a common concern and potentially involved in provoking degenerative diseases worldwide. BMAA may likewise be bioaccumulated in other cyanobacterial based food webs within ecosystems outside Guam, and it is proposed that such webs may exist in the Baltic Sea, with its massive occurrence of cyanobacteria (blooms).

  • 325.
    Jonasson, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Berntzon, Lotta
    Stockholm University, Faculty of Science, Department of Botany.
    Spacil, Zdenek
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. Charles University Prague, Czech Republic .
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ronnevi, Lars-Olof
    Rasmussen, Ulla
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Transfer of a cyanobacterial neurotoxin within a temperate aquatic ecosystem suggests pathways for human exposure2010In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 107, no 20, p. 9252-9257Article in journal (Refereed)
    Abstract [en]

    beta-methylamino-L-alanine (BMAA), a neurotoxic nonprotein amino acid produced by most cyanobacteria, has been proposed to be the causative agent of devastating neurodegenerative diseases on the island of Guam in the Pacific Ocean. Because cyanobacteria are widespread globally, we hypothesized that BMAA might occur and bioaccumulate in other ecosystems. Here we demonstrate, based on a recently developed extraction and HPLC-MS/MS method and long-term monitoring of BMAA in cyanobacterial populations of a temperate aquatic ecosystem (Baltic Sea, 2007-2008), that BMAA is biosynthesized by cyanobacterial genera dominating the massive surface blooms of this water body. BMAA also was found at higher concentrations in organisms of higher trophic levels that directly or indirectly feed on cyanobacteria, such as zooplankton and various vertebrates (fish) and invertebrates (mussels, oysters). Pelagic and benthic fish species used for human consumption were included. The highest BMAA levels were detected in the muscle and brain of bottom-dwelling fishes. The discovery of regular biosynthesis of the neurotoxin BMAA in a large temperate aquatic ecosystem combined with its possible transfer and bioaccumulation within major food webs, some ending in human consumption, is alarming and requires attention.

  • 326.
    Jonasson, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Larsson, Ulf
    Söderbäck, Erik
    Quantitative real-time reverse transcriptase PCR to monitor the cellular phosphate status of bloom-forming cyanobacterium Nodularia spumigena in the Baltic SeaManuscript (Other academic)
  • 327.
    Jonasson, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Söderbäck, Erik
    Molecular monitoring of phosphate stress in Anabaena PCC 7120 using quantitative real-time PCR and PyrosequencingManuscript (Other academic)
  • 328.
    Jonasson, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Vintila, Simina
    Stockholm University, Faculty of Science, Department of Botany.
    Sivonen, Kaarina
    El-Shehawy, Rehab
    Stockholm University, Faculty of Science, Department of Botany.
    Expression of the nodularin synthetase genes in the Baltic Sea bloom-former cyanobacterium Nodularia spumigena strain AV1.2008In: FEMS Microbiol Ecol, ISSN 0168-6496, Vol. 65, no 1, p. 31-39Article in journal (Refereed)
    Abstract [en]

    Cyanobacterial blooms in the Baltic Sea are a common phenomenon and are formed by the heterocystous, filamentous species Nodularia spumigena. The toxicity of these blooms is attributed to the hepatotoxin nodularin, produced by N. spumigena. Little is known regarding the regulatory mechanisms or environmental signaling that control nodularin production. Here we report the characterization of the transcriptional expression pattern of the nodularin synthetase gene cluster (nda) during phosphate depletion, and nitrogen supplementation. Real-time PCR analysis of these genes revealed that while cells continuously expressed the nda cluster, the expression of all nda genes increased when cells were subjected to phosphate depletion, and decreased in the presence of ammonium. In contrast to the shifts in expression, the intracellular and extracellular nodularin concentrations did not vary significantly during the treatments.

  • 329.
    Jonasson, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Vintila, Simina
    Sivonen, Karina
    El-Shehawy, Rehab
    Expression analysis of the nodularin synthesis genes in the Baltic Sea bloom-former cyanobacterium Nodularia spumigena in response to nitrogen and phosphate stressManuscript (Other academic)
  • 330. Jongejans, Eelke
    et al.
    Jorritsma-Wienk, Linda D.
    Becker, Ute
    Dostal, Petr
    Mildén, Mikael
    Stockholm University, Faculty of Science, Department of Botany.
    de Kroon, Hans
    Region versus site variation in the population dynamics of three short-lived perennials2010In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 98, no 2, p. 279-289Article in journal (Refereed)
    Abstract [en]

    1. When range shifts or invasions of plant species are studied, it is important to know whether large-scale spatial variation in a species' demography can be ignored or approximated by variation observed over smaller spatial scales. 2. Here, we studied the population dynamics of three similar (as shown by elasticity analysis) short-lived perennial plant species in multiple sites in different European countries over 2 years. We constructed a total of 40 transition matrices and analysed the spatio-temporal variation in the projected population growth rate (lambda) with spatially nested life table response experiments (LTRE). 3. All species (Carlina vulgaris, Tragopogon pratensis and Hypochaeris radicata) showed considerable life-history variation among regions on top of variation among sites within regions. 4. Net variance contributions (NVC), a novel LTRE statistic, revealed that in each species, variation in one group of vital rates contributed most to variation in lambda among regions as well as among sites. However, that most important type of vital rates differed between species: plant growth in C. vulgaris, flower head production in T. pratensis and establishment probability of seedlings in H. radicata. The rankings of the NVCs of other vital rates varied between site and region effects, suggesting that buffering through negative vital rate correlations varies over different spatial scales, while the identity of the main contributor to lambda variation is more constant. 5. Temporal effects were smaller than spatial effects, but the LTREs showed strong interactions between time and space (region or site), suggesting that the effect of, e.g. climate fluctuations are not synchronized throughout the distribution of a species. 6. Synthesis. This study shows that the life histories of plant species are distinguishable even when mean elasticity values show only small differences, and that life histories vary over the distribution range of a species. Demographic differences over large spatial scales can therefore only be partly substituted by small scale spatial variation in modelling studies on the population dynamics of a species across its entire distribution.

  • 331. Jonsson,
    et al.
    Bertilsson,
    Stockholm University, Faculty of Science, Department of Botany.
    Ehrlén,
    Stockholm University, Faculty of Science, Department of Botany.
    Lönn,
    Genetic divergence of climatically marginal populations of Vicia pisiformis on the Scandinavian peninsula2008In: HereditasArticle in journal (Refereed)
  • 332. Jonsson, Knud A.
    et al.
    Bowie, Rauri C. K.
    Nylander, Johan A. A.
    Stockholm University, Faculty of Science, Department of Botany.
    Christidis, Les
    Norman, Janette A.
    Fjeldsa, Jon
    Biogeographical history of cuckoo-shrikes (Aves: Passeriformes): transoceanic colonization of Africa from Australo-Papua2010In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 37, no 9, p. 1767-1781Article in journal (Refereed)
    Abstract [en]

    Aim Cuckoo-shrikes and allies (Campephagidae) form a radiation of birds widely distributed in the Indo-Pacific and Africa. Recent studies on the group have been hampered by poor taxon sampling, causing inferences about systematics and biogeography to be rather speculative. With improved taxon sampling and analyses within an explicit spatiotemporal framework, we elucidate biogeographical patterns of dispersal and diversification within this diverse clade of passerine birds. Location Africa, Asia, Australo-Papua, the Pacific, the Philippines and Wallacea. Methods We use model-based phylogenetic methods (MrBayes and garli) to construct a phylogenetic hypothesis of the core Campephagidae (Campephagidae with the exclusion of Pericrocotus). The phylogeny is used to assess the biogeographical history of the group with a newly developed Bayesian approach to dispersal-vicariance analysis (Bayes-diva). We also made use of a partitioned beast analysis, with several calibration points taken from island ages, passerine mitochondrial substitution rates and secondary calibration points for passerine birds, to assess the timing of diversification and dispersal. Results We present a robust molecular phylogeny that includes all genera and 84% of the species within the core Campephagidae. Furthermore, we estimate divergence dates and ancestral area relationships. We demonstrate that Campephagidae originated in Australo-Papua with a single lineage (Pericrocotus) dispersing to Asia early. Later, there was further extensive transoceanic dispersal from Australo-Papua to Africa involving lineages within the core Campephagidae radiation. Main conclusions The phylogenetic relationships, along with the results of the ancestral area analysis and the timing of dispersal events, support a transoceanic dispersal scenario from Australo-Papua to Africa by the core Campephagidae. The sister group to core Campephagidae, Pericrocotus, dispersed to mainland Asia in the late Oligocene. Asia remained uncolonized by the core Campephagidae until the Pliocene. Transoceanic dispersal is by no means an unknown phenomenon, but our results represent a convincing case of colonization over a significant water gap of thousands of kilometres from Australo-Papua to Africa.

  • 333. Jormalainen, Veijo
    et al.
    Wikström, Sowa A.
    Stockholm University, Faculty of Science, Department of Botany.
    Honkanen, Tuija
    Fouling mediates grazing: intertwining of resistances to multiple enemies in the brown alga Fucus vesiculosus2008In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 155, no 3, p. 559-569Article in journal (Refereed)
    Abstract [en]

    Macroalgae have to cope with multiple natural enemies, such as herbivores and epibionts. As these are harmful for the host, the host is expected to show resistance to them. Evolution of resistance is complicated by the interactions among the enemies and the genetic correlations among resistances to different enemies. Here, we explored genetic variation in resistance to epibiosis and herbivory in the brown alga Fucus vesiculosus, both under conditions where the enemies coexisted and where they were isolated. F. vesiculosus showed substantial genetic variation in the resistance to both epibiosis and grazing. Grazing pressure on the alga was generally lower in the presence than in the absence of epibiota. Furthermore, epibiosis modified the susceptibility of different algal genotypes to grazing. Resistances to epibiosis and grazing were independent when measured separately for both enemies but positively correlated when both these enemies coexisted. Thus, when the enemies coexisted, the fate of genotypes with respect to these enemies was intertwined. Genotypic correlation between phlorotannins, brown-algal phenolic secondary metabolites, and the amount of epibiota was negative, indicating that these compounds contribute to resistance to epibiosis. In addition, phlorotannins correlated also with the resistance to grazing, but this correlation disappeared when grazing occurred in the absence of epibiota. This indicates that the patterns of selection for the type of the resistance as well as for the resistance traits vary with the occurrence patterns of the enemies.

  • 334. Juřičková, L.
    et al.
    Horsák, M
    Cameron, R.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany. Växtekologi.
    Míkovcová, A.
    Hlaváč, J.Č.
    Rohovec, J.
    Land snail distribution patterns within a site: the role of different calcium sources2008In: European Journal of Soil Biology, Vol. 44, p. 172-179Article in journal (Refereed)
  • 335.
    Jónsdóttir, Guðrún Á.
    Stockholm University, Faculty of Science, Department of Botany.
    Dynamics of seashore populations of Agrostis stolonifera, Festuca rubra and Poa irrigata1993Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The dynamics of tillers of natural populations of three cohabiting perennial grass species Agrostis stolonifera, Festuca rubra and Poa irrigata were studied for five years in a Baltic seashore meadow. A demographic approach based on numerical changes over time was used. Analyses were made to determine the effects of temperature and precipitation and the effects of intraspecific and interspecific density of the species on rates of tiller birth and death were assessed. For A. stolonifera and F. rubra, temporal and spatial differences in vital rates were studied and consequences of that differences for long term population processes were studied by population matrix models. Competitive relationships between the three grasses were studied experimentally.

    Recruitment was mainly by vegetative tillers, produced continuously throughout the growing season. Rates of tiller birth and death were high, particularly in A. stolonifera consequently the life span of individual tiller was short. Considerable year -to-year was found in birth and death rates and the birth rates of tillers in all species were positively related to summer precipitation. Positive relationships were found between death and birth rates in F. rubra. In A. stolonifera the risk of tiller death was constant through the life but increased with age in the two other species. Most tillers of all species died for unknown reasons. Relationships between tiller death and density of tillers could not be confirmed nor could relationships between the rate of tiller death and weather functions. The proportion of flowering tillers was low in all species. Survival probabilities for tillers of A. stolonifera and F. rubra were not homogeneous in time or space and for that species the temporal and spatial variation in vital rates was large enough to have influences on long-term processes such as population growth rate. For A. stolonifera and F. rubra indications were fond that contribution of the youngest age class, through daughter tiller production, was of major importance to the population growth rate. All three species were affected by between species competition except F. rubra when grown as the more frequent component in mixture with P. irrigata. The pattern of interactions between the species was not influenced by initial density, but it was influenced by relative frequency of a species in mixture with another species.

    In this study a picture of everchangin tiller populations was found, turnover rate of tillers was high and considerable variation in vital rates was confirmed. For A. stolonifera and F. rubra mosaic of increasing an decreasing populations was found in time and space. Despite this the populations of each species remained relatively stable over the study period as a whole. 

  • 336.
    Kader, Abdul
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany.
    Cytosolic calcium and pH signaling in plants under salinity stress2010In: Plant signaling and behavior, Vol. 5, no 3, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Calcium is one of the essential nutrients for growth and development of plants. It is an

    important component of various structures in cell wall and membranes. Besides some

    fundamental roles under normal condition, calcium functions as a major secondarymessenger

    molecule in plants under different developmental cues and various stress

    conditions including salinity stress. Also changes in cytosolic pH, pHcyt, either individually,

    or in coordination with changes in cytosolic Ca2+ concentration, [Ca2+]cyt, evoke a wide range

    of cellular functions in plants including signal transduction in plant-defense responses against

    stresses. It is believed that salinity stress, like other stresses, is perceived at cell membrane,

    either extra cellular or intracellular, which then triggers an intracellular-signaling cascade

    including the generation of secondary messenger molecules like Ca2+ and protons. The

    variety and complexity of Ca2+ and pH signaling result from the nature of the stresses as well

    as the tolerance level of the plant species against that specific stress. The nature of changes in

    [Ca2+]cyt concentration, in terms of amplitude, frequency and duration, is likely very

    important for decoding the specific downstream responses for salinity stress tolerance in

    planta. It has been observed that the signatures of [Ca2+]cyt and pH differ in various studies

  • 337.
    Kader, Abdul
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Sedel, Thorsten
    University of Bielefeld, Germany.
    Golldack, Dortje
    University of Bielefeld, Germany.
    Yemelyanov, Vladislav
    State University of St. Petersburg, Russia.
    Sodium sensing induces different changes in free cytosolic calcium concentration and pH in salt-tolerant and -sensitive rice (Oryza sativa) cultivars2007In: Physiologia Plantarum, ISSN 0031-9317, Vol. 130, p. 99-111Article in journal (Refereed)
    Abstract [en]

    Perception of salt stress in plant cells induces a change in the free cytosolic Ca2+, [Ca2+]cyt, which transfers downstream reactions toward salt tolerance. Changes in cytosolic H+ concentration, [H+]cyt, are closely linked to the [Ca2+]cyt dynamics under various stress signals. In this study, salt-induced changes in [Ca2+]cyt, and [H+]cyt and vacuolar [H+] concentrations were monitored in single protoplasts of rice (Oryza sativa L. indica cvs. Pokkali and BRRI Dhan29) by fluorescence microscopy. Changes in cytosolic [Ca2+] and [H+] were detected by use of the fluorescent dyes acetoxy methyl ester of calcium-binding benzofuran and acetoxy methyl ester of 2', 7'-bis-(2- carboxyethyl)-5-(and-6) carboxyfluorescein, respectively, and for vacuolar pH, fluorescent 6-carboxyfluorescein and confocal microscopy were used. Addition of NaCl induced a higher increase in [Ca21]cyt in the salt-tolerant cv. Pokkali than in the salt-sensitive cv. BRRI Dhan29. From inhibitor studies, we

    conclude that the internal stores appear to be the major source for [Ca2+]cyt increase in Pokkali, although the apoplast is more important in BRRI Dhan29. The [Ca21]cyt measurements in rice also suggest that Na1 should be sensed inside the cytosol, before any increase in [Ca2+]cyt occurs. Moreover, our results with individual mesophyll protoplasts suggest that ionic stress causes an increase in [Ca2+]cyt and that osmotic stress sharply decreases [Ca2+]cyt in rice. The [pH]cyt was differently shifted in the two rice cultivars in response to salt stress and may be coupled to different activities of the H1-ATPases. The changes in vacuolar pH were correlated with the expressional analysis of rice

    vacuolar H+-ATPase in these two rice cultivars.

  • 338.
    Kader, M Abdul
    et al.
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Adaptation mechanisms in Rice (Oryza sativa) under salt stress2007In: 2nd World Conference on Stress: 3rd Cell Stress Society International Congress on Stress Responses in Biology and Mediin, 2007, p. 1-Conference paper (Refereed)
    Abstract [en]

    The project focuses on two important aspects of Na+ toxicity in salt-tolerant rice cv. Pokkali and salt-sensitive cv. BRRI Dhan29, namely i) how Na+ stress induces a change in cytosolic Ca2+, [Ca2+]cyt, and pH, [pH]cyt, and ii) how cells could maintain a low cytosolic Na+ and/or Na+/K+ ratio. The salt-induced changes in [Ca2+]cyt and [pH]cyt and their sources were monitored in single rice protoplasts by fluorescence microscopy. The expression of the transporter genes OsHKT1, OsHKT2 and OsVHA, which are thought to play a significant role in maintaining correct cytosolic Na+ and or Na+/K+ ratio, were examined in both rice cultivars under salt stress condition by real time RT-PCR and in situ PCR. The results show that Na+ must be sensed inside the cytosol, before any changes in [Ca2+]cyt and [pH]cyt occur. Sensing of Na+ induced different changes in [Ca2+]cyt and [pH]cyt in the two rice cultivars with different sources for the changes. The [pH]cyt changes were coupled to different

    H+-ATPases in the two cultivars. The expression analysis of OsHKT1, OsHKT2 and OsVHA showed variable and cell- specific induction in these cultivars under salt stress condition. The important mechanism for salt tolerance in cv. Pokkali was to keep cytosolic Na+ at a low level, by reducing Na+-influx (through down-regulation of OsHKT1) and compartmentalizing cytosolic Na+ into the vacuole (through the induction of vacuolar H+ATPase OsVHA, an energizer for the tonoplast Na+/H+ antiporter). Pokkali might also induce increased uptake of K+ through the induction of OsHKT2, as evident in this study. Vacuolar

    compartmentalization of Na+ is also present in salt-sensitive cv. BRRI Dhan29, but to a lesser extent and much later than in cv. Pokkali. The results suggest that the signaling and subsequent adaptive responses in the salt-tolerant rice cv. Pokkali are different from that in the salt-sensitive cv. BRRI Dhan29.

  • 339.
    Kader, Md Abdul
    et al.
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany.
    Cellular traits for sodium tolerance in rice (Oryza sativa L.)2008Conference paper (Other academic)
    Abstract [en]

    Under salt stress the ability to reduce Na+-influx into the cytosol, and subsequently increase the compartmentalization of cytosolic Na+ into the vacuole, appeared to be the significant salt-tolerance determinant in salt-tolerant cv. Pokkali. These mechanisms were either absent or less efficient in the salt-sensitive cv. BRRI Dhan29.

  • 340.
    Kader, Md Abdul
    et al.
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Cellular traits for sodium tolerance in rice (Oryza sativa L.)2008In: Plant Biotechnology, ISSN 0289577, Vol. 25, no 3, p. 247-255Article in journal (Refereed)
    Abstract [en]

    Abstract

    The present review focuses on two important aspects of Na+ toxicity in rice (Oryza sativa L.), i) that Na+ stress induces different changes in cytosolic Ca2+, [Ca2+]cyt, and pH, [pH]cyt, in tolerant and sensitive cultivars, and ii) that cells from a tolerant cultivar can better maintain a low cytosolic Na+ and/or Na+/K+ ratio. Experiments with single rice protoplasts, fluorescence microscopy and specific ion-selective dyes suggest that Na+ must be sensed inside the cytosol, before any prolonged changes in [Ca2+]cyt and [pH]cyt occur. Inhibitor analyses show that Na+-induced increase in [pH]cyt in the tolerant cv. Pokkali, and a decrease in [pH]cyt in the sensitive cv. BRRI DHan29, likely are coupled to different H+-ATPases. Expression analysis of OsHKT2;1 (previous name OsHKT1), OsHKT2;2 (previous name OsHKT2) and OsVHA transcripts in rice using RT-PCR and fluorescence in situ-PCR, shows a variable and cell- specific induction in the two rice cultivars under salt stress condition. We conclude that the transient uptake of Na+, which occurs only in the tolerant cultivar, and the fast compartmentalization of Na+ into the vacuole, probably are the most important cellular traits for Na+-tolerance in rice. The low [Na+]cyt in cv. Pokkali might depend on the fast down-regulation of OsHKT2;1, causing less uptake of Na+, and fast up-regulation of the OsVHA transcript, and subsequent activation of the Na+/H+-anti-porter in the tonoplast. To decrease the cytosolic Na+/K+ ratio under Na+ toxicity, cv. Pokkali may also induce increased uptake of K+ through induction of OsHKT2;2, and other specific K+-transporter genes.

  • 341.
    Kader, Md Abdul
    et al.
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany.
    Mechanisms for cytosolic Na+ homeostasis in rice under salt stress2009In: Global Challenges in Research Cooperation, May 27-29 2008, Uppsala, Sweden, 2009, p. 1-Conference paper (Other academic)
    Abstract [en]

    Under salt stress the ability to reduce Na+-influx into the cytosol, and subsequently increase the compartmentalization into the vacuole, appeared to be the significant salt-tolerance determinants in the salt-tolerant rice, cv. Pokkali. These mechanisms were either absent, or less efficient, in the salt-sensitive rice cv. BRRI Dhan29.

  • 342.
    Kader, Md Abdul
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Rasmusson, Allan
    University of Lund.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany.
    Expressions of HKT members in salt-tolerant and salt-sensitive rice cultivars are differentially regulated under salinity stress2009In: 9th IMPB Congress October 2009: Abiotic stress, Water, salts, minerals, 2009Conference paper (Other academic)
  • 343.
    Kainulainen, Kent
    Stockholm University, Faculty of Science, Department of Botany.
    Evolution and biodiversity of the Ixoroideae (Rubiaceae)2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The phylogenetic relationships within subfamily Ixoroideae of the coffee family are investigated by phylogenetic reconstruction of molecular data, including regions of the chloroplast DNA (matK, ndhF, rbcL, rps16, trnH-psbA, trnS-G, and trnT-F), and the nuclear ribosomal DNA (ITS). The evolution of morphological characters within the group are inferred, with focus on characters used in classification. Ixoroideae have primarily been characterized by secondary pollen presentation, contorted corolla aestivation, and fleshy fruits. Secondary pollen presentation appears synapomorhic of a clade comprising the Ixoroideae crown group together with Retiniphyllum, whereas contorted corolla aestivation has evolved earlier and is synapomorphic for the crown group, Retiniphyllum, and Steenisia. Capsules likely represent a plesiomorphy from which various dry or fleshy indehiscent fruits have evolved independently in different clades. Reductions in seed number have also occured in many clades, none of which shows a secondary increase in the number of seeds.

    Within Ixoroideae, the phylogeny and tribal delimitations of Alberteae and Condamineeae are studied in more detail. The former appears restricted to Alberta, Nematostylis, and Razafimandimbisonia, a new genus described here. The Condamineeae are a diverse tribe largely unresolved in previous molecular phylogenetic studies. Our results support a synonymization of both Calycophylleae and Hippotideae, because these are nested within the Condamineeae. Ancestral state reconstructions indicate that intrapetiolar stipules, poricidal anthers, and protogyny, otherwise uncommon characters in Rubiaceae, all have evolved more than once in the Condamineeae.

    The rare genera Jackiopsis, Glionnetia, and Trailliaedoxa previously not included in molecular phylogenetic analyses, are all found nested within the Ixoroideae, and their systematic positions are discussed. The genera Bathysa, Calycophyllum, Elaeagia, and Rustia do not appear monophyletic. Consequently, resurrections of the names Holtonia, Schizocalyx, and Semaphyllanthe, and synonymizations of Phitopis (as Schizocalyx) and Tresanthera (as Rustia) are proposed. Also proposed are five new tribal names for clades that are not associated with any previously described tribes in the phylogenetic hypotheses presented.

  • 344.
    Kainulainen, Kent
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Mouly, Arnaud
    Khodabandeh, Anbar
    Stockholm University, Faculty of Science, Department of Botany.
    Bremer, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Molecular phylogenetic analysis of the tribe Alberteae (Rubiaceae), with description of a new genus, Razafimandimbisonia2009In: Taxon, ISSN 0040-0262, E-ISSN 1996-8175, Vol. 58, no 3, p. 757-768Article in journal (Refereed)
    Abstract [en]

    The tribe Alberteae, presently classified in the subfamily Ixoroideae (Rubiaceae), has historically been an artificial grouping of genera. In the present study, phylogenetic analyses of the chloroplast DNA markers rbcL, ndhF, trnS-G, trnT-F and trnH-psbA as well as the ITS region of the nuclear ribosomal DNA, are done to assess the delimitation of Alberteae. The resulting phylogenetic hypothesis is highly resolved, with most clades strongly supported. The genus Alberta is found to be paraphyletic as presently circumscribed. As a consequence, we propose the new genus Razafimandimbisonia Kainul. & B. Bremer to accommodate the Malagasy species. The newly delimited Alberta is distinguished by having two calycophylls that expand after anthesis as well as awl-shaped stigma lobes. Razafimandimbisonia is distinguished from the remaining Alberteae by having dehiscent fruits and anthers without basal appendages. We demonstrate that the genera Airosperma, Boholia and Crossopteryx are not associated with Alberteae, as has previously been suggested. Alberteae is considered restricted to the genus Alberta endemic to Southeast Africa, and the two Malagasy endemic genera Nematostylis and Razafimandimbisonia.

  • 345.
    Kainulainen, Kent
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Persson, Claes
    University of Gothenburg, Department of Systematic Botany.
    Eriksson, Torsten
    Swedish Museum of Natural History, Entomology Department.
    Bremer, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Molecular systematics and morphological character evolution of the Condamineeae (Rubiaceae)2010In: American Journal of Botany, ISSN 0002-9122, E-ISSN 1537-2197, Vol. 97, no 12, p. 1961-1981Article in journal (Refereed)
    Abstract [en]

    • Premise of the study: The Condamineeae have in previous molecular studies been shown to be part of an early-divergent cladewithin the subfamily Ixoroideae, together with the tribes Calycophylleae, and Hippotideae, and genera of the former Cinchoneae and Rondeletieae. Generic relationships within this clade have, however, remained largely unresolved

    .• Methods: In this study, the systematics of the Condamineeae was further examined by phylogenetic reconstruction of six cpDNA regions and one nrDNA region using parsimony and Bayesian Markov chain Monte Carlo inference. Morphological character evolution within the tribe was assessed by ancestral state reconstruction using likelihood optimization of characters onto Bayesian trees.

    • Key results: Calycophylleae appears polyphyletic. “Hippotideae” is monophyletic but nested within the Condamineeae. The phylogenetic hypotheses presented support a resurrection of the genera Holtonia, Schizocalyx, and Semaphyllanthe. Furthermore, Bathysa is found to be polyphyletic, Tresanthera is found nested within Rustia, and the taxonomically disputed genus Dialypetalanthus is here shown to be sister to a BothriosporaWittmackanthus clade. Morphological ancestral state reconstructions indicate that protogyny have evolved at least two times within the tribe and that indehiscent fruits, loculicidal fruit dehiscence, and intrapetiolar stipules have evolved independently several times. The occurrence of calycophylls (leaf-like calyx lobes), poricidal anthers, and winged seeds also appear homoplastic within the tribe.

    • Conclusions : A diagnosis and delimitation of the tribe Condamineeae is presented, with taxonomic proposals to synonymize Tresanthera and to transfer several species of Bathysa as well as Phitopis to a resurrected Schizocalyx.

  • 346.
    Kainulainen, Kent
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Razafimandimbison, Sylvain
    Stockholm University, Faculty of Science, Department of Botany.
    Bremer, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Phylogeny and evolution of secondary pollen presentation, corolla aestivation patterns, fruit types, and seed number in the Ixoroideae (Rubiaceae)Manuscript (preprint) (Other academic)
    Abstract [en]

    Phylogenetic reconstructions using Bayesian and parsimony analyses of six chloroplast DNA region were performed in order to investigate character evolution and tribal relationships within the subfamily Ixoroideae (Rubiaceae). In the inferred phylogenetic hypotheses, the tribal relationships were mostly well supported, with the subfamily comprised of a crown group of two major sister clades termed the Coffeeae-alliance and Vanguerieae-alliance respectively, and a basal grade comprising Condamineeae, Henriquezieae, Posoquerieae, Retiniphyleae, Sipaneeae, and Steenisia. Five new tribes are here recognized (Airospermeae, Augusteae, Scyphiphoreae, Steenisieae and Trailliaedoxeae). Secondary pollen presentation, corolla aestivation patterns,fruit types, and number of ovules are all characters that have been considered of great importance in the classification of Rubiaceae. Ancestral state reconstructions of these characters using likelihood optimization indicate that secondary pollen presentation is synapomorphic for a clade comprising the Ixoroideae crown group and Retiniphyllum, whereas left-contorted corolla aestivation is synapomorphic for a clade comprising the crown group, Retiniphyllum, and Steenisia. Capsular fruits with numerous seeds are plesiomorphic in Ixoroideae, from which dry or fleshy indehiscent fruits have evolved numerous times independently. Reductions in seed number appears to have occurred within several lineages, none of which show a secondary increase in the number of seeds.

  • 347. Kangwe,, Juma
    et al.
    Semesi, I. Sware
    Beer, Sven
    Mtolera, Matern
    Björk, Mats
    Stockholm University, Faculty of Science, Department of Botany.
    Carbonate Production by Calcareous Algae in aSeagrass-Dominated System: The Example of Chwaka Bay. CHAPTER 8: CHAPTER 82012In: People, Nature and Research in Chwaka Bay, Zanzibar, Tanzania / [ed] de la Torre-Castro M. and Lyimo T.J., Zanzibar: WIOMSA , 2012Chapter in book (Refereed)
  • 348.
    Kangwe, Juma W.
    Stockholm University, Faculty of Science, Department of Botany.
    Calcareous Algae of a Tropical Lagoon: Primary Productivity, Calcification and Carbonate Production2005Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The green algae of the genus Halimeda Lamouroux (Chlorophyta, Bryopsidales) and the encrusting loose-lying red coralline algae (Rhodophyta, Corallinales) known as rhodoliths are abundant and widespread in all oceans. They significantly contribute to primary productivity while alive and production of CaCO3 rich sediment materials on death and decay. Carbonate rich sediments are important components in the formation of Coral Reefs and as sources of inorganic carbon (influx) in tropical and subtropical marine environments. This study was initiated to attempt to assess their ecological significance with regard to the above mentioned roles in a tropical lagoon system, Chwaka bay (Indian Ocean), and to address some specific objectives on the genus Halimeda (Chlorophyta, Bryopsidales) and the loose-lying coralline algae (rhodoliths).

    Four Halimeda species were taxonomically identified in the area. The species identified are the most common inhabitants of the world’s tropical and subtropical marine environments, and no new species were encountered. Using Satellite remote sensing technique in combination with the percentage cover data obtained from ground-truthing field work conducted in the area using quadrants, the spatial and seasonal changes of Submerged Aquatic Macrophytes (SAV) were evaluated. SAV percentage cover through ground-truthing was; 24.4% seagrass, 16% mixed Halimeda spp., 5.3% other macroalgae species while 54.3% remained unvegetated. No significant changes in SAV cover was observed for the period investigated, except in some smaller regions where both loss and gains occurred. The structural complexity of SAV (shoot density, above-ground biomass and canopy height) for most common seagrass communities from six meadows, dominated by Thalassia hemprichii, Enhalus acoroides and Thalassodendron ciliatum, as well as mixed meadows, were estimated and evaluated. Relative growth of Halimeda species was up to 1 segment tip-1 day-1. The number of segments produced was highest in hot season. Differences between the numbers of segments produced were insignificant between the two sites investigated. The C/N ratios obtained probably shows that Halimeda species experience nitrogen limitation in the area and may be a factor among others responsible for the varying growth of species obtained. However, this can be a normal ratio for calcified algae due to high CaCO3 content in their tissues. Standing biomass of mixed Halimeda species averaged between 500-600 g dw m-2 over the bay, while the mean cover in Halimeda meadows was about 1560 g dw m-2. Carbonate production in Halimeda beds varied between 17-57 g CaCO3 m-2 day-1 and for H. macroloba between 12-91 g CaCO3 m-2 day-1. This indicates a high annual input of carbonate in the area. Decomposition of Halimeda using litter bag experiments at site I and II gave a decomposition rate (k) of 0.0064 and k = 0.0091 day-1 ash-free dry weight (AFDW) respectively. Hence it would take 76-103 days for 50% of the materials to decompose.

    Adding inhibitors or varying the pH significantly reduced inorganic carbon uptake, and demonstrated that the two photosynthesis and calcification were linked. Addition of TRIS strongly inhibited photosynthesis but not calcification, suggesting the involvement of proton pumps in the localized low pH acid zones and high pH basic zones. The high pH zones were maintained by the proton pumps maintaining high calcification, while TRIS was competing for proton uptake from acid zones causing photosynthesis to drop. Rhodoliths were found to maintain high productivity at a temperature of 34oC, and even at 37oC. It is therefore concluded that, rhodoliths are well adapted to high temperatures and excess light, a behaviour which enables them to thrive even in intertidal areas.

  • 349.
    Kangwe, Juma W.
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Mtolera, Matern S. P.
    Björk, Mats
    Inorganic carbon uptake into photosynthesis and calcification in two common Halimeda speciesManuscript (Other academic)
  • 350.
    Kangwe, Juma W.
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Mtolera, Matern S. P.
    Kautsky, L
    Björk, M
    Growth and standing biomass of Halimeda (Bryopsidales) species and their contribution to sediment production in a tropical bayManuscript (Other academic)
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