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  • 1.
    Abdelfattah, Ahmed
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Università Mediterranea di Reggio Calabria, Italy.
    Sanzani, Simona M.
    Wisniewski, Michael
    Berg, Gabriele
    Cacciola, Santa O.
    Schena, Leonardo
    Revealing Cues for Fungal Interplay in the Plant-Air Interface in Vineyards2019Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 10, artikel-id 922Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plant-associated microorganisms play a crucial role in plant health and productivity. Belowground microbial diversity is widely reported as a major factor in determining the composition of the plant microbiome. In contrast, much less is known about the role of the atmosphere in relation to the plant microbiome. The current study examined the hypothesis that the atmospheric microbiome influences the composition of fungal communities of the aboveground organs flowers, fruit, and leaves) of table grape and vice versa. The atmosphere surrounding grape plantings exhibited a significantly higher level of fungal diversity relative to the nearby plant organs and shared a higher number of phylotypes 5,536 OTUs, 40.3%) with the plant than between organs of the same plant. Using a Bayesian source tracking approach, plant organs were determined to be the major source of the atmospheric fungal community 92%). In contrast, airborne microbiota had only a minor contribution to the grape microbiome, representing the source of 15, 4, and 35% of the fungal communities of leaves, flowers, and fruits, respectively. Moreover, data indicate that plant organs and the surrounding atmosphere shared a fraction of each other's fungal communities, and this shared pool of fungal taxa serves as a two-way reservoir of microorganisms. Microbial association analysis highlighted more positive than negative interactions between fungal phylotypes. Positive interactions were more common within the same environment, while negative interactions appeared to occur more frequently between different environments, i. e., atmosphere, leaf, flower, and fruit. The current study revealed the interplay between the fungal communities of the grape phyllosphere with the surrounding air. Plants were identified as a major source of recruitment for the atmospheric microbiome, while the surrounding atmosphere contributed only a small fraction of the plant fungal community. The results of the study suggested that the plant-air interface modulates the plant recruitment of atmospheric fungi, taking a step forward in understanding the plant holobiont assembly and how the atmosphere surrounding plants plays a role in this process. The impact of plants on the atmospheric microbiota has several biological and epidemiological implications for plants and humans.

  • 2. Billault-Penneteau, Benjamin
    et al.
    Sandré, Aline
    Folgmann, Jessica
    Parniske, Martin
    Pawlowski, Katharina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Dryas as a Model for Studying the Root Symbioses of the Rosaceae2019Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 10, artikel-id 661Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nitrogen-fixing root nodule symbiosis is restricted to four plant orders: Fabales (legumes), Fagales, Cucurbitales and Rosales (Elaeagnaceae, Rhamnaceae, and Rosaceae). Interestingly all of the Rosaceae genera confirmed to contain nodulating species (i.e., Cercocarpus, Chamaebatia, Dryas, and Purshia) belong to a single subfamily, the Dryadoideae. The Dryas genus is particularly interesting from an evolutionary perspective because it contains closely related nodulating (Dryas drummondii) and non-nodulating species (Dryas octopetala). The close phylogenetic relationship between these two species makes Dryas an ideal model genus to study the genetic basis of nodulation by whole genome comparison and classical genetics. Therefore, we established methods for plant cultivation, transformation and DNA extraction for these species. We optimized seed surface sterilization and germination methods and tested growth protocols ranging from pots and Petri dishes to a hydroponic system. Transgenic hairy roots were obtained by adapting Agrobacterium rhizogenes-based transformation protocols for Dryas species. We compared several DNA extraction protocols for their suitability for subsequent molecular biological analysis. Using CTAB extraction, reproducible PCRs could be performed, but CsCI gradient purification was essential to obtain DNA in sufficient purity for high quality de novo genome sequencing of both Dryas species. Altogether, we established a basic toolkit for the culture, transient transformation and genetic analysis of Dryas sp.

  • 3. Demchenko, Kirill N.
    et al.
    Voitsekhovskaja, Olga V.
    Pawlowski, Katharina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Plasmodesmata without callose and calreticulin in higher plants - open channels for fast syrnplastic transport?2014Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plasmodesmata (PD) represent membrane-lined channels that link adjacent plant cells across the cell wall. PD of higher plants contain a central tube of endoplasmic reticulum (ER) called desmotubule. Membrane and lumen proteins seem to be able to move through the desmotubule, but most transport processes through PD occur through the cytoplasmic annulus (Brunkard (Bale 2013). Calreticulin (CRT), a highly conserved Ca2+-binding protein found in all multicellular eukaryotes, predominantly located in the ER, was shown to localize to PD, though not all PD accumulate CRT. In nitrogen-fixing actinorhizal root nodules of the Australian tree Casuarina glauca, the primary walls of infected cells containing the microsymbiont become lignified upon infection. TEM analysis of these nodules showed that during the differentiation of infected cells, PD connecting infected cells, and connecting infected and adjacent uninfected cells, were reduced in number as well as diameter (Schubert eta, 2013). In contrast with PD connecting young infected cells, and most PD connecting mature infected and adjacent uninfected cells, PD connecting mature infected cells did not accumulate CRT. Furthermore, as shown here, these PD were not associated with callose, and based on their diameter, they probably had lost their desmotubules. We speculate that either this is a slow path to PD degradation, or that the loss of callose accumulation and presumably also desmotubules leads to the PD becoming open channels and improves metabolite exchange between cells.

  • 4.
    Demina, Irina V.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Maity, Pooja Jha
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Nagchowdhury, Anurupa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Ng, Jason L. P.
    van der Graaff, Eric
    Demchenko, Kirill N.
    Roitsch, Thomas
    Mathesius, Ulrike
    Pawlowski, Katharina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Accumulation of and Response to Auxins in Roots and Nodules of the Actinorhizal Plant Datisca glomerata Compared to the Model Legume Medicago truncatula2019Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 10, artikel-id 1085Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Actinorhizal nodules are structurally different from legume nodules and show a greater similarity to lateral roots. Because of the important role of auxins in lateral root and nodule formation, auxin profiles were examined in roots and nodules of the actinorhizal species Datisca glomerata and the model legume Medicago truncatula. The auxin response in roots and nodules of both species was analyzed in transgenic root systems expressing a beta-glucuronidase gene under control of the synthetic auxin-responsive promoter DR5. The effects of two different auxin on root development were compared for both species. The auxin present in nodules at the highest levels was phenylacetic acid (PAA). No differences were found between the concentrations of active auxins of roots vs. nodules, while levels of the auxin conjugate indole-3-acetic acid-alanine were increased in nodules compared to roots of both species. Because auxins typically act in concert with cytokinins, cytokinins were also quantified. Concentrations of cis-zeatin and some glycosylated cytokinins were dramatically increased in nodules compared to roots of D. glomerata, but not of M. truncatula. The ratio of active auxins to cytokinins remained similar in nodules compared to roots in both species. The auxin response, as shown by the activation of the DR5 promoter, seemed significantly reduced in nodules compared to roots of both species, suggesting the accumulation of auxins in cell types that do not express the signal transduction pathway leading to DR5 activation. Effects on root development were analyzed for the synthetic auxin naphthaleneacetic acid (NAA) and PAA, the dominant auxin in nodules. Both auxins had similar effects, except that the sensitivity of roots to PAA was lower than to NAA. However, while the effects of both auxins on primary root growth were similar for both species, effects on root branching were different: both auxins had the classical positive effect on root branching in M. truncatula, but a negative effect in D. glomerata. Such a negative effect of exogenous auxin on root branching has previously been found for a cucurbit that forms lateral root primordia in the meristem of the parental root; however, root branching in D. glomerata does not follow that pattern.

  • 5. Deng, Nan
    et al.
    Hou, Chen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Hunan Cili Forest Ecosystem State Research Station, China.
    Liu, Caixia
    Li, Minghe
    Bartish, Igor
    Tian, Yuxin
    Chen, Wei
    Du, Changjian
    Jiang, Zeping
    Shi, Shengqing
    Significance of Photosynthetic Characters in the Evolution of Asian Gnetum (Gnetales)2019Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 10, artikel-id 39Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gnetum is a genus in the Gnetales that has a unique but ambiguous placement within seed plant phylogeny. Previous studies have shown that Gnetum has lower values of photosynthetic characters than those of other seed plants, but few Gnetum species have been studied, and those that have been studied are restricted to narrow taxonomic and geographic ranges. In addition, the mechanism underlying the lower values of photosynthetic characters in Gnetum remains poorly understood. Here, we investigated the photosynthetic characters of a Chinese lianoid species, i.e., Gnetum parvifolium, and co-occurring woody angiosperms growing in the wild, as well as seedlings of five Chinese Gnetum species cultivated in a greenhouse. The five Gnetum species had considerably lower values for photosynthesis parameters (net photosynthetic rate, transpiration rate, intercellular CO2 concentration, and stomatal conductance) than those of other seed plant representatives. Interrelated analyses revealed that the low photosynthetic capacity may be an intrinsic property of Gnetum, and may be associated with its evolutionary history. Comparison of the chloroplast genomes (cpDNAs) of Gnetum with those of other seed plant representatives revealed that 17 coding genes are absent from the cpDNAs of all species of Gnetum. This lack of multiple functional genes from the cpDNAs probably leads to the low photosynthetic rates of Gnetum. Our results provide a new perspective on the evolutionary history of the Gnetales, and on the ecophysiological and genomic attributes of tropical biomes in general. These results could also be useful for the breeding and cultivation of Gnetum.

  • 6. Grossmann, Jonas
    et al.
    Fernández, Helena
    Chaubey, Pururawa M.
    Valdés, Ana E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Linnean Centre for Plant Biology, Sweden.
    Gagliardini, Valeria
    Cañal, María J.
    Russo, Giancarlo
    Grossniklaus, Ueli
    Proteogenomic Analysis Greatly Expands the Identification of Proteins Related to Reproduction in the Apogamous Fern Dryopteris affinis ssp affinis2017Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 8, artikel-id 336Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Performing proteomic studies on non-model organisms with little or no genomic information is still difficult. However, many specific processes and biochemical pathways occur only in species that are poorly characterized at the genomic level. For example, many plants can reproduce both sexually and asexually, the first one allowing the generation of new genotypes and the latter their fixation. Thus, both modes of reproduction are of great agronomic value. However, the molecular basis of asexual reproduction is not well understood in any plant. In ferns, it combines the production of unreduced spores (diplospory) and the formation of sporophytes from somatic cells (apogamy). To set the basis to study these processes, we performed transcriptomics by next-generation sequencing (NGS) and shotgun proteomics by tandem mass spectrometry in the apogamous fern D. affinis ssp. affinis. For protein identification we used the public viridiplantae database (VPDB) to identify orthologous proteins from other plant species and new transcriptomics data to generate a species-specific transcriptome database (SSTDB). In total 1,397 protein clusters with 5,865 unique peptide sequences were identified (13 decoy proteins out of 1,410, protFDR 0.93% on protein cluster level). We show that using the SSTDB for protein identification increases the number of identified peptides almost four times compared to using only the publically available VPDB. We identified homologs of proteins involved in reproduction of higher plants, including proteins with a potential role in apogamy. With the increasing availability of genomic data from non -model species, similar proteogenomics approaches will improve the sensitivity in protein identification for species only distantly related to models.

  • 7. Hoeber, Stefanie
    et al.
    Fransson, Petra
    Prieto-Ruiz, Ines
    Manzoni, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Weih, Martin
    Two Salix Genotypes Differ in Productivity and Nitrogen Economy When Grown in Monoculture and Mixture2017Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 8, artikel-id 231Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Individual plant species or genotypes often differ in their demand for nutrients; to compete in a community they must be able to acquire more nutrients (i.e., uptake efficiency) and/or use them more efficiently for biomass production than their competitors. These two mechanisms are often complementary, as there are inherent trade-offs between them. In a mixed-stand, species with contrasting nutrient use patterns interact and may use their resources to increase productivity in different ways. Under contrasting nutrient availabilities, the competitive advantages conferred by either strategy may also shift, so that the interaction between resource use strategy and resource availability ultimately determines the performance of individual genotypes in mixtures. The aim was to investigate growth and nitrogen (N) use efficiency of two willow (Salix) genotypes grown in monoculture and mixture in a fertilizer contrast. We explored the hypotheses that (1) the biomass production of at least one of the involved genotypes should be greater when grown in mixture as compared to the corresponding monoculture when nutrients are the most growth-limiting factor; and (2) the N economy of individual genotypes differs when grown in mixture compared to the corresponding monoculture. The genotypes 'Tora' (Salix schwerinii x S. viminalis) and 'Loden' (S. dasyclados), with contrasting phenology and functional traits, were grown from cuttings in a growth container experiment under two nutrient fertilization treatments (high and low) in mono-and mixed-culture for 17 weeks. Under low nutrient level, 'Tora' showed a higher biomass production (aboveground biomass, leaf area productivity) and N uptake efficiency in mixture than in monoculture, whereas 'Loden' showed the opposite pattern. In addition, 'Loden' showed higher leaf N productivity but lower N uptake efficiency than 'Tora.' The results demonstrated that the specific functional trait combinations of individual genotypes affect their response to mixture as compared to monoculture. Plants grown in mixture as opposed to monoculture may thus increase biomass and vary in their response of N use efficiency traits. However, young plants were investigated here, and as we cannot predict mixture response in mature stands, our results need to be validated at field scale.

  • 8.
    Hughes, P. William
    Max Planck Institute for Plant Breeding Research, Germany; University of Cologne, Germany.
    Minimal-Risk Seed Heteromorphism: Proportions of Seed Morphs for Optimal Risk-Averse Heteromorphic Strategies2018Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 9, artikel-id 1412Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seed heteromorphism is the reproductive strategy characterized by the simultaneous production of multiple seed types. While comparing heteromorphic to monomorphic strategies is mathematically simple, there is no explicit test for assessing which ratio of seed morphs minimizes fitness variance, and hence offers a basis for comparing different heteromorphic strategies. Such a test may be particularly valuable when more than two distinct morphs are present, since many strategies may have equivalent geometric fitnesses. As noted by Gillespie (1974), in these cases avoiding rare but evolutionarily important instances of severe reductions in fitness involves the minimization of variation in fitness—i.e., risk. Here I compute the optimal proportions of two or more seed morphs for heteromorphic strategies that either: (1) minimize total fitness variance; or (2) maximize the fitness-risk ratio—i.e., the “extra” fitness accrued per unit of “extra” fitness variance. This work thereby provides a testable null hypothesis to estimate the optimal frequencies of seed morphs when multiple heteromorphic strategies have evolved in environments with severe fitness risks. Moreover, it also permits the calculation of expected seed morph frequencies when more than two seed morphs are produced.

  • 9. Kiryushkin, Alexey S.
    et al.
    Ilina, Elena L.
    Puchkova, Vera A.
    Guseva, Elizaveta D.
    Pawlowski, Katharina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Demchenko, Kirill N.
    Lateral Root Initiation in the Parental Root Meristem of Cucurbits: Old Players in a New Position2019Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 10, artikel-id 365Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    While in most higher plants, including the model system Arabidopsis thaliana, the formation of lateral root primordia is induced in the elongation zone of the parental root, in seven plant families, including Cucurbitaceae, an alternative root branching mechanism is established such that lateral roots are initiated directly in the apical meristem of the parental root. In Arabidopsis, the transcription factor GATA23 and MEMBRANE-ASSOCIATED KINASE REGULATOR4 (MAKR4) are involved in the gene regulatory network of lateral root initiation. Among all marker genes examined, these are the earliest known marker genes up-regulated by auxin during lateral root initiation. In this study, putative functional orthologs of Arabidopsis GATA23 and MAKR4 were identified in cucumber (Cucumis sativus) and squash (Cucurbita pepo). Both cucurbits contained 26 genes encoding GATA family transcription factors and only one MAKR4 gene. Phylogenetic and transcriptional analysis of up-regulation by auxin led to the identification of GATA23 putative functional orthologs in Cucurbitaceae - CpGATA24 and CsGATA24. In squash, CpMAKR4 was up-regulated by naphthylacetic acid (NM) and, similar to MAKR4 in Arabidopsis, indole-3-butyric acid (IBA). A detailed analysis of the expression pattern of CpGATA24 and CpMAKR4 in squash roots from founder cell specification until emergence of lateral root primordia was carried out using promoter-fluorescent reporter gene fusions and confocal microscopy. Their expression was induced in the protoxylem, and then expanded to founder cells in the pericycle. Thus, while the overall expression pattern of these genes was significantly different from that in Arabidopsis, in founder cells their expression was induced in the same order as in Arabidopsis. Altogether, these findings suggest that in Cucurbitaceae the putative functional orthologs of GATA23 and MAKR4 might play a role in founder cell specification and primordium positioning during lateral root initiation. The role of the protoxylem in auxin transport as a trigger of founder cells specification and lateral root initiation is discussed.

  • 10. Kollars, Nicole M.
    et al.
    Henry, Amy K.
    Whalen, Matthew A.
    Boyer, Katharyn E.
    Cusson, Mathieu
    Eklöf, Johan S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Hereu, Clara M.
    Jorgensen, Pablo
    Kiriakopolos, Stephanie L.
    Reynolds, Pamela L.
    Tomas, Fiona
    Turner, Mo S.
    Ruesink, Jennifer L.
    Meta-Analysis of Reciprocal Linkages between Temperate Seagrasses and Waterfowl with Implications for Conservation2017Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 8, artikel-id 2119Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Multi-trophic conservation and management strategies may be necessary if reciprocal linkages between primary producers and their consumers are strong. While herbivory on aquatic plants is well-studied, direct top-down control of seagrass populations has received comparatively little attention, particularly in temperate regions. Herein, we used qualitative and meta-analytic approaches to assess the scope and consequences of avian (primarily waterfowl) herbivory on temperate seagrasses of the genus Zostera. Meta-analyses revealed widespread evidence of spatio-temporal correlations between Zostera and waterfowl abundances as well as strong top-down effects of grazing on Zostera. We also documented the identity and diversity of avian species reported to consume Zostera and qualitatively assessed their potential to exert top-down control. Our results demonstrate that Zostera and their avian herbivores are ecologically linked and we suggest that bird herbivory may influence the spatial structure, composition, and functioning of the seagrass ecosystem. Therefore, the consequences of avian herbivory should be considered in the management of seagrass populations. Of particular concern are instances of seagrass overgrazing by waterfowl which result in long-term reductions in seagrass biomass or coverage, with subsequent impacts on local populations of waterfowl and other seagrass-affiliated species. While our results showed that bird density and type may affect the magnitude of the top-down effects of avian herbivory, empirical research on the strength, context-dependency, and indirect effects of waterfowl-Zostera interactions remains limited. For example, increased efforts that explicitly measure the effects of different functional groups of birds on seagrass abundance and/or document how climate change-driven shifts in waterfowl migratory patterns impact seagrass phenology and population structure will advance research programs for both ecologists and managers concerned with the joint conservation of both seagrasses and their avian herbivores.

  • 11.
    Krautz, Robert
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för molekylär biovetenskap, Wenner-Grens institut.
    Arefin, Badrul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för molekylär biovetenskap, Wenner-Grens institut.
    Theopold, Ulrich
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för molekylär biovetenskap, Wenner-Grens institut.
    Damage signals in the insect immune response2014Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 5, artikel-id 342Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Insects and mammals share an ancient innate immune system comprising both humoral and cellular responses. The insect immune system consists of the fat body, which secretes effector molecules into the hemolymph and several classes of hemocytes, which reside in the hemolymph and of protective border epithelia. Key features of wound- and immune responses are shared between insect and mammalian immune systems including the mode of activation by commonly shared microbial (non-self) patterns and the recognition of these patterns by dedicated receptors. It is unclear how metazoan parasites in insects, which lack these shared motifs, are recognized. Research in recent years has demonstrated that during entry into the insect host, many eukaryotic pathogens leave traces that alert potential hosts of the damage they have afflicted. In accordance with terminology used in the mammalian immune systems, these signals have been dubbed danger- or damage-associated signals. Damage signals are necessary byproducts generated during entering hosts either by mechanical or proteolytic damage. Here, we briefly review the current stage of knowledge on how wound closure and wound healing during mechanical damage is regulated and how damage-related signals contribute to these processes. We also discuss how sensors of proteolytic activity induce insect innate immune responses. Strikingly damage-associated signals are also released from cells that have aberrant growth, including tumor cells. These signals may induce apoptosis in the damaged cells, the recruitment of immune cells to the aberrant tissue and even activate humoral responses. Thus, this ensures the removal of aberrant cells and compensatory proliferation to replace lost tissue. Several of these pathways may have been co-opted from wound healing and developmental processes.

  • 12. Mazzuca, Silvia
    et al.
    Björk, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Beer, S.
    Felisberto, P.
    Gobert, S.
    Procaccini, G.
    Runcie, J.
    Silva, J.
    Borges, A. V.
    Brunet, C.
    Buapet, Pimchanok
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Champenois, W.
    Costa, M. M.
    D'Esposito, D.
    Gullström, Martin
    Lejeune, P.
    Lepoint, G.
    Olive, I.
    Rasmusson, Lina M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Richir, J.
    Ruocco, M.
    Serra, I. A.
    Spadafora, A.
    Santos, Rui
    Establishing research strategies, methodologies and technologies to link genomics and proteomics to seagrass productivity, community metabolism, and ecosystem carbon fluxes2013Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 4, artikel-id 38Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research. This enables the prediction of change and possibly the mitigation of the consequences of anthropogenic impacts. One major aim of the European Cooperation in Science and Technology (COST) Action ES0609 Seagrasses productivity. From genes to ecosystem management, is the calibration and synthesis of various methods and the development of innovative techniques and protocols for studying seagrass ecosystems. During 10 days, 20 researchers representing a range of disciplines (molecular biology, physiology, botany, ecology, oceanography, and underwater acoustics) gathered at The Station de Recherches Sous-marines et Oceanographiques (STARESO, Corsica) to study together the nearby Posidonia oceanica meadow. STARESO is located in an oligotrophic area classified as pristine site where environmental disturbances caused by anthropogenic pressure are exceptionally low. The healthy P. oceanica meadow, which grows in front of the research station, colonizes the sea bottom from the surface to 37 m depth. During the study, genomic and proteomic approaches were integrated with ecophysiological and physical approaches with the aim of understanding changes in seagrass productivity and metabolism at different depths and along daily cycles. In this paper we report details on the approaches utilized and we forecast the potential of the data that will come from this synergistic approach not only for P. oceanica but for seagrasses in general.

  • 13. Murray, Michelle
    et al.
    Soh, Wuu Kuang
    Yiotis, Charilaos
    Batke, Sven
    Parnell, Andrew C.
    Spicer, Robert A.
    Lawson, Tracy
    Caballero, Rodrigo
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Wright, Ian J.
    Purcell, Conor
    McElwain, Jennifer C.
    Convergence in Maximum Stomatal Conductance of C-3 Woody Angiosperms in Natural Ecosystems Across Bioclimatic Zones2019Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 10, artikel-id 558Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stomatal conductance (g(s)) in terrestrial vegetation regulates the uptake of atmospheric carbon dioxide for photosynthesis and water loss through transpiration, closely linking the biosphere and atmosphere and influencing climate. Yet, the range and pattern of g(s) in plants from natural ecosystems across broad geographic, climatic, and taxonomic ranges remains poorly quantified. Furthermore, attempts to characterize g(s) on such scales have predominantly relied upon meta-analyses compiling data from many different studies. This approach may be inherently problematic as it combines data collected using unstandardized protocols, sometimes over decadal time spans, and from different habitat groups. Using a standardized protocol, we measured leaf-level g(s) using porometry in 218 C-3 woody angiosperm species in natural ecosystems representing seven bioclimatic zones. The resulting dataset of 4273 g(s) measurements, which we call STraits (Stomatal Traits), was used to determine patterns in maximum g(s) (g(smax)) across bioclimatic zones and whether there was similarity in the mean g(smax) of C3 woody angiosperms across ecosystem types. We also tested for differential g(smax) in two broadly defined habitat groups - open-canopy and understory-subcanopy - within and across bioclimatic zones. We found strong convergence in mean g(smax) of C3 woody angiosperms in the understory-subcanopy habitats across six bioclimatic zones, but not in open-canopy habitats. Mean g(smax) in open-canopy habitats (266 +/- 100 mmol m(-2) s(-1)) was significantly higher than in understory-subcanopy habitats (233 +/- 86 mmol m(-2) s(-1)). There was also a central tendency in the overall dataset to operate toward a g(smax) of similar to 250 mmol m(-2) s(-1). We suggest that the observed convergence in mean g(smax) of C3 woody angiosperms in the understory-subcanopy is due to a buffering of g(smax) against macroclimate effects which will lead to differential response of C3 woody angiosperm vegetation in these two habitats to future global change. Therefore, it will be important for future studies of g(smax) to categorize vegetation according to habitat group.

  • 14. Netsvetov, Maksym
    et al.
    Prokopuk, Yulia
    Puchalka, Radoslaw
    Koprowski, Marcin
    Klisz, Marcin
    Romenskyy, Maksym
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Imperial College London, United Kingdom.
    River Regulation Causes Rapid Changes in Relationships Between Floodplain Oak Growth and Environmental Variables2019Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 10, artikel-id 96Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The radial growth of pedunculate oak (Quercus robur), a species often ecologically dominating European deciduous forests, is closely tied up with local environmental variables. The oak tree-ring series usually contain a climatic and hydrologic signal that allows assessing the main drivers of tree growth in various ecosystems. Understanding the climate-growth relationship patterns in floodplains is important for providing insights into the species persistence and longevity in vulnerable riverine ecosystems experiencing human-induced hydrology alteration. Here, we use 139 years long instrumental records of local temperature, precipitation, and water levels in the Dnipro River in Kyiv to demonstrate that the implementation of river regulation has decoupled the established relationship between the radial growth of floodplain oak and local hydro-climatic conditions. Before the river flow has been altered by engineering modifications of 1965-1977, the water level in the Dnipro River was the key driver of oak radial growth, as reflected in the tree-ring width and earlywood width. The construction of two dams has altered the seasonal distribution of water level diminishing the positive effect of high water on oak growth and subsequently reversing this trend to negative, resulting from a seasonal ground water surplus. The decrease in the correlation between oak growth indices and the river's water level in April-June was unprecedentedly rapid and clearly distinguishable among other changes in the growth-to-climate relationship. Our findings further demonstrate that trees growing in areas exposed to urban development are the most susceptible to downside effects of river regulation.

  • 15.
    Salgado, Marco G.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    van Velzen, Robin
    Van Nguyen, Thanh
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Battenberg, Kai
    Berry, Alison M.
    Lundin, Daniel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik. Linnaeus University, Sweden.
    Pawlowski, Katharina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Comparative Analysis of the Nodule Transcriptomes of Ceanothus thyrsiflorus (Rhamnaceae, Rosales) and Datisca glomerata (Datiscaceae, Cucurbitales)2018Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 9, artikel-id 1629Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two types of nitrogen-fixing root nodule symbioses are known, rhizobial and actinorhizal symbioses. The latter involve plants of three orders, Fagales, Rosales, and Cucurbitales. To understand the diversity of plant symbiotic adaptation, we compared the nodule transcriptomes of Datisca glomerata (Datiscaceae, Cucurbitales) and Ceanothus thyrsiflorus (Rhamnaceae, Rosales); both species are nodulated by members of the uncultured Frankia clade, cluster II. The analysis focused on various features. In both species, the expression of orthologs of legume Nod factor receptor genes was elevated in nodules compared to roots. Since arginine has been postulated as export form of fixed nitrogen from symbiotic Frankia in nodules of D. glomerata, the question was whether the nitrogen metabolism was similar in nodules of C. thyrsiflorus. Analysis of the expression levels of key genes encoding enzymes involved in arginine metabolism revealed up-regulation of arginine catabolism, but no up-regulation of arginine biosynthesis, in nodules compared to roots of D. glomerata, while arginine degradation was not upregulated in nodules of C. thyrsiflorus. This new information corroborated an arginine-based metabolic exchange between host and microsymbiont for D. glomerata, but not for C. thyrsiflorus. Oxygen protection systems for nitrogenase differ dramatically between both species. Analysis of the antioxidant system suggested that the system in the nodules of D. glomerata leads to greater oxidative stress than the one in the nodules of C. thyrsiflorus, while no differences were found for the defense against nitrosative stress. However, induction of nitrite reductase in nodules of C. thyrsiflorus indicated that here, nitrite produced from nitric oxide had to be detoxified. Additional shared features were identified: genes encoding enzymes involved in thiamine biosynthesis were found to be upregulated in the nodules of both species. Orthologous nodule-specific subtilisin-like proteases that have been linked to the infection process in actinorhizal Fagales, were also upregulated in the nodules of D. glomerata and C. thyrsiflorus. Nodule-specific defensin genes known from actinorhizal Fagales and Cucurbitales, were also found in C. thyrsiflorus. In summary, the results underline the variability of nodule metabolism in different groups of symbiotic plants while pointing at conserved features involved in the infection process.

  • 16. Wang, Xiaofeng
    et al.
    Yang, Bao
    Charpentier Ljungqvist, Fredrik
    Stockholms universitet, Humanistiska fakulteten, Historiska institutionen.
    The Vulnerability of Qilian Juniper to Extreme Drought Events2019Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 10, artikel-id 1191Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Identifying which trees are more vulnerable to extreme climatic events is a challenging problem in our understanding of forest and even ecosystem dynamics under climate change scenarios. As one of the most widely distributed tree species across the arid and semi-arid northeastern Tibetan Plateau, Qilian juniper (Juniperus przewalskii Kom.), is the main component of the local forest ecosystem, providing critical insurance for the ecological security of the surrounding areas. However, this species's ability to cope with climate extremes (especially drought) has not been adequately assessed. Here, we apply a dendroecological approach that considers indices of resistance and resilience to quantify the vulnerability of Qilian junipers to the extreme drought events of 1957, 1966, 1979, and 1995. A total of 532 Qilian juniper trees from different age stages (100-1,100 years) and altitudes [3,500-4,000 m above sea level (a.s.l.)] were studied to assess their response characteristics during these four drought extremes. We conclude that drought extremes have a significant negative impact on the growth of Qilian juniper. The oldest Qilian junipers at the lower altitudes constituted the most vulnerable populations across the northeastern Tibetan Plateau and were characterized by the lowest resistance values, the narrowest annual rings, and the highest proportion of missing rings during the four drought years. Tree resilience after droughts was strongly related to the intensity of the drought event and did not change with tree age or elevation. A threshold of tree tolerance to drought may exist, with the more vulnerable tree individuals (e.g., the oldest Qilian junipers from lower altitudes) being exposed to the highest mortality risk when drought intensity exceeds the threshold value. Such a threshold needs further consideration, through the study of trees that have died (or are about to die) due to extreme droughts.

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