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  • 1. Arnqvist, L
    et al.
    Dutta, P C
    Jonsson, Lisbeth
    Södertörn University, Avdelning Naturvetenskap.
    Sitbon, F
    Reduction of cholesterol and glycoalkaloid levels in transgenic potato plants by overexpression of a type 1 sterol methyltransferase cDNA2003In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 131, no 4, p. 1792-1799Article in journal (Refereed)
    Abstract [en]

    Transgenic potato (Solanum tuberosum cv Desiree) plants overexpressing a soybean (Glycine max) type 1 sterol methyltransferase (GmSMT1) cDNA were generated and used to study sterol biosynthesis in relation to the production of toxic glycoalkaloids. Transgenic plants displayed an increased total sterol level in both leaves and tubers, mainly due to increased levels of the 24-ethyl sterols isofucosterol and sitosterol. The higher total sterol level was due to increases in both free and esterified sterols. However, the level of free cholesterol, a nonalkylated sterol, was decreased. Associated with this was a decreased glycoalkaloid level in leaves and tubers, down to 41% and 63% of wild-type levels, respectively. The results show that glycoalkaloid biosynthesis can be down-regulated in transgenic potato plants by reducing the content of free nonalkylated sterols, and they support the view of cholesterol as a precursor in glycoalkaloid biosynthesis.

  • 2. Gao, L L
    et al.
    Knogge, W
    Delp, Gabriele
    Södertörn University, School of Chemistry, Biology, Geography and Environmental Science.
    Smith, F A
    Smith, S E
    Expression patterns of defense-related genes in different types of arbuscular mycorrhizal development in wild-type and mycorrhiza-defective mutant tomato2004In: Molecular Plant-Microbe Interactions, ISSN 0894-0282, E-ISSN 1943-7706, Vol. 17, no 10, p. 1103-1113Article in journal (Refereed)
    Abstract [en]

    The expression of defense-related genes was analyzed in the interactions of six arbuscular mycorrhizal (AM) fungi with the roots of wild-type tomato (Lycopersicon esculentum Mill.) cv. 76R and of the near-isogenic mycorrhiza-defective mutant rmc. Depending on the fungal species, wild-type tomato forms both major morphological AM types, Arum and Paris. The mutant rmc blocks the penetration of the root surface or invasion of the root cortex by most species of AM fungi, but one fungus has been shown to develop normal mycorrhizas. In the wild-type tomato, accumulation of mRNA representing a number of defense-related genes was low in Arum-type interactions, consistent with findings for this AM morphotype in other plant species. In contrast, Paris-type colonization, particularly by members of the family Gigasporaceae, was accompanied by a substantial transient increase in expression of some defense-related genes. However, the extent of root colonization did not differ significantly in the two wild-type AM morphotypes, suggesting that accumulation of defense gene products per se does not limit mycorrhiza development. In the mutant, interactions in which the fungus failed to penetrate the root lacked significant accumulation of defense gene mRNAs. However, phenotypes in which the fungus penetrated epidermal or hypodermal cells were associated with an enhanced and more prolonged gene expression. These results are discussed in relation to the mechanisms that may underlie the specificity of the interactions between AM fungi and the rmc mutant.

  • 3.
    Hellblom, Frida
    et al.
    Södertörn University, Avdelning Naturvetenskap.
    Axelsson, Lennart
    External HCO3- dehydration maintained by acid zones in the plasma membrane is an important component of the photosynthetic carbon uptake in Ruppia cirrhosa2003In: Photosynthesis Research, ISSN 0166-8595, E-ISSN 1573-5079, Vol. 77, no 2-3, p. 173-181Article in journal (Refereed)
  • 4. Hjortswang, H I
    et al.
    Sundås Larsson, Annika
    Södertörn University, Avdelning Naturvetenskap.
    Bharathan, G
    Bozhkov, P V
    von Arnold, S
    Vahala, T
    KNOTTED1-like homeobox genes of a gymnosperm, Norway spruce, expressed during somatic embryogenesis2002In: Plant physiology and biochemistry (Paris), ISSN 0981-9428, E-ISSN 1873-2690, Vol. 40, no 10, p. 837-843Article in journal (Refereed)
    Abstract [en]

    Two Norway spruce (Picea abies (L.) Karst.) genes belonging to class I of the KNOTTED1-like homeobox (KNOX) genes, HBK2 and HBK3, were cloned with PCR-based methods. The expression of these and a previously characterised related gene, HBK1, in different organs and during somatic embryogenesis was studied with RTPCR. Transcripts of all three genes were detected in stems, roots and in cone buds, but not in needles. HBK1 and HBK3 are expressed throughout development in a normal cell line with embryogenic potential and in a cell line unable to form somatic embryos. HBK2 is expressed in the normal cell line, but not in the developmentally arrested cell line. This suggests that the HBK2 gene is involved in the somatic embryo development.

  • 5. Johansson, Victor
    et al.
    Bergman, Karl-Olof
    Lättman, Håkan
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Environmental science.
    Milberg, Per
    Tree and site quality preferences of six epiphytic lichens growing on oaks in southeastern Sweden2009In: Annales Botanici Fennici, ISSN 0003-3847, E-ISSN 1797-2442, Vol. 46, no 6, p. 496-506Article in journal (Refereed)
    Abstract [en]

    Oaks (Quercus robur) can reach a considerable age, which makes them an important substrate for many epiphytic lichens, including several red-listed species. We studied the importance of tree size and other environmental factors for the occurrence of six epiphytic lichens at two sites, in southeastern Sweden, differing in quality as judged by tree size distribution and number of old trees. The effects of tree circumference, light availability, trunk inclination and site were analysed. Results showed that different lichen species responded differently to these factors, but, overall, tree size was most important for lichen occurrence. Five species showed a positive relation to tree size, but the 50% probability of occurrence was reached at different tree sizes among these species and there were also site differences. This study shows that the maintenance of old trees is crucial for several lichen species, which highlights the importance of long-term management plans.

  • 6.
    Larsson, Kristina A. E.
    et al.
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Saheed, Sefiu A.
    Gradin, Therese
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Delp, Gabriele
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Karpinska, Barbara
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Botha, Christiaan E. J.
    Jonsson, Lisbeth M. V.
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Differential regulation of 3-aminomethylindole/N-methyl-3-aminomethylindole N-methyltransferase and gramine in barley by both biotic and abiotic stress conditions2011In: Plant physiology and biochemistry (Paris), ISSN 0981-9428, E-ISSN 1873-2690, Vol. 49, no 1, p. 96-102Article in journal (Refereed)
    Abstract [en]

    The expression of NMT (3-aminomethylindole/N-methyl-3-aminomethylindole N-methyltransferase; EC 2.1.1.), involved in the biosynthesis of the indole alkaloid gramine, was investigated in aphid-infested barley (Hordeum vulgare L). NMT is induced by methyl jasmonate and it was hypothesized that the gene would be more strongly upregulated in aphid-resistant barley. We examined the effects of feeding by three aphid species; Russian wheat aphid (Diuraphis noxia Mordvilko), rose-grain aphid (Metopolophium dirhodum Walker) and bird cherry-oat aphid (Rhopalosiphum padi L.) on barley genotypes with varying resistance characteristics. The barley genotypes selected included the cultivar Libra, known to upregulate gramine after feeding by Schizaphis graminum. Infestation by R. padi and M. dirhodum resulted in higher NMT expression in the doubled haploid line 5172-28:4 (DH28:4), which has moderate resistance against R. padi, but not in other aphid barley combinations. None of the aphid plant combinations had however increased gramine, suggesting that aphid-induction of gramine is specific to S. graminum. The increased abundance of NMT transcript in aphid-infested DH28:4 did not lead to higher amounts of NMT protein or NMT enzyme activity, neither did 200 times upregulation of NMT transcript in cotyledons incubated with methyl jasmonate, illustrating that even large differences measured at transcript level may have no metabolic consequences. Drought stress or treatments with abscisic acid did lead to higher gramine concentrations in several barley cultivars, but without any concomitant increase of NMT transcripts. Thus, the regulation of the biosynthetic pathway to gramine at transcript and metabolite level diverges during two different stress conditions.

  • 7.
    Lättman, Håkan
    Södertörn University, School of Life Sciences, Environmental science. Södertörn University, School of Life Sciences, Biology.
    Studies on spatial and temporal distributions of epiphytic lichens2010Report (Other academic)
    Abstract [en]

    Lichens are an important group of organisms in terms of environmental issues, conservation biology and biodiversity, since lichens are sensitive to changes in their environment. Therefore it is important that we develop our understanding of the factors that affect lichen distribution. In this thesis both spatial and temporal distributions of epiphytic lichens at different scales have been studied in southern Sweden.

    Brokind was chosen as the study site to investigate the succession of epiphytic lichens on Quercus robur using a chronosequencial approach. Fourteen of the investigated taxa out of 50 proved to be significant. The taxa were divided into three groups according to whether they occurred on young, middle-aged or old trees.

    Generation length of the red-listed lichen Cliostomum corrugatum was examined using Bjärka-Säby as the study site. The results showed that the average age of an individual of C. corrugatum is 25–30 years at the onset of spore production.

    Generation length of the red-listed lichen Cliostomum corrugatum was examined using Bjärka-Säby as the study site. The results showed that the average age of an individual of C. corrugatum is 25–30 years at the onset of spore production.

    The rarity of C. corrugatum was also examined. DNA of an intron from 85 samples, collected at five sites in Östergötland, yielded 11 haplotypes. Results from the coalescent analysis, mantel test and AMOVA indicated that C. corrugatum have a high ability to disperse. The study concluded that its rarity is most likely connected with the low amount of available habitat, old Q. robur.

    The changes in the distribution of epiphytic lichens in southern Sweden between 1986 and 2003 were compared. For each year a centroid was calculated on all combinations of tree and lichen species. The three significant cases showed that the centroid movement pointed toward a north-east or north-north-east direction.

    Regional gradients of abundance and size of Hypogymnia physodes at 66 sites in southern Sweden were examined. The coordinate system rotating the reference system of investigated sites around the origin was used to search for the best explanatory power for the angle of the explanatory variables. The results showed a gradient of increase in the probability of occurrence in a north-north-east direction and an increase in diameter on thallus size in a west-north-west direction.

  • 8.
    Lättman, Håkan
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science. Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Biology. Linköping University.
    Bergman, K. -O
    Linköping University.
    Rapp, M.
    Linköping University.
    Tälle, M.
    Linköping University.
    Westerberg, L.
    Linköping University.
    Milberg, P.
    Linköping University.
    Decline in lichen biodiversity on oak trunks due to urbanization2014In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 32, no 4, p. 518-528Article in journal (Other academic)
    Abstract [en]

    Biodiversity often suffers from urbanization. In the present study, we focused on how the duration of urbanization affects the richness of 17 epiphytic lichen species and their cover on large oaks in urban environments in a city of 100 000 inhabitants in southeast Sweden. We also surveyed trees in adjacent rural areas, selected to have similar distributions of tree trunk circumference and surrounding oak density (within 300 m). Lichen richness and cover were lower on urban trees compared to rural trees. Furthermore, richness and cover decreased with the length of time that urban trees had been surrounded by houses. Most of the species that were analysed demonstrated a decline in occurrence with respect to the duration of housing development. The reduction in the probability of occurrence varied from 60% (Calicium viride, Evernia prunastri), 80% (Chrysothrix candelaris) to 90% (Ramalina spp.) during the considered 160-year period of urbanization. Therefore, even if valuable trees survive over the course of development, their lichen biota is likely to become depleted over time. © 2014 The Authors.

  • 9. Mattsson, Jan-Eric
    Lichenes Austroamericani ex Herbario Regnelliano: Fasc. 20–221999Book (Other academic)
  • 10. Nikus, J
    et al.
    Esen, A
    Jonsson, Lisbeth M V
    Södertörn University, Avdelning Naturvetenskap.
    Cloning of a plastidic rye (Secale cereale) beta-glucosidase cDNA and its expression in Escherichia coli2003In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 118, no 3, p. 337-345Article in journal (Refereed)
    Abstract [en]

    The cDNA for a beta-glucosidase (EC3.2.1.21) was isolated from rye (Secale cereale, cv Motto) and the sequence corresponding to the mature protein cloned into pET21a expression vector and used for transformation of Escherichia coli. The recombinant beta-glucosidase expressed in E. coli was recognized by antibodies to maize beta-glucosidase and exhibited the same kinetic properties on the endogenous substrates hydroxamic acid glucosides and artificial substrates as the native enzyme purified from rye. The enzyme monomer had an apparent molecular weight of about 67 kDa. The isolated cDNA was analysed with web-based chloroplast targeting prediction programs. The programs predicted a chloroplast targeting peptide with a cleavage site between amino acid 49 and 50. Sequence alignment of the plastidic rye beta-glucosidase showed that the putative sites for substrate specificity of maize Glu1, W378 and F198 (F197) are conserved in the rye enzyme, whereas F205, F466 and A467 of maize Glu1 are exchanged for histidine, glycine and serine, respectively, in rye. The plastidic beta-glucosidase is expressed in all plant parts and the highest levels were found in the coleoptile and mesocotyl.

  • 11.
    Norbäck Ivarsson, Lena
    et al.
    Stockholm University, Department of Ecology, Environment and Plant Sciences.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Lundberg, Johannes
    Swedish Museum of Natural History, Department of Botany.
    Sallstedt, Therese
    Swedish Museum of Natural History, Department of Paleobiology.
    Rydin, Catarina
    Stockholm University, Department of Ecology, Environment and Plant Sciences.
    Epilithic and aerophilic diatoms in the artificial environment of Kungsträdgården metro station, Stockholm, Sweden2013In: International Journal of Speleology, ISSN 0392-6672, E-ISSN 1827-806X, Vol. 42, no 3, p. 289-297Article in journal (Refereed)
    Abstract [en]

    The Kungsträdgården metro station is an artificial and urban subsurface environment illuminated with artificial light. Its ecosystem is almost completely unknown and as a first step to better understand the biology and rock wall habitats the diatom flora was investigated. A total of 12 species were found growing on the rock walls of Kungsträdgården metro station. The results show the diatom flora in Kungsträdgården to be dominated by e.g. Diadesmis contentaDiadesmis perpusillaPinnularia appendiculataNitzschia amphibiaNitzschia sinuata and Diploneis ovalis. One species, Caloneis cf. aerophila, has never been reported from Sweden before. Significant differences in the species composition between the sampling sites indicate Kungsträdgården metro station to be a heterogeneous habitat that provides different microhabitats.

  • 12.
    Plue, Jan
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science. Stockholm University.
    Vandepitte, Katrien
    Laboratory of Plant Conservation and Population Biology, Heverlee, Belgium.
    Honnay, Olivier
    Laboratory of Plant Conservation and Population Biology, Heverlee, Belgium.
    Cousins, Sara A O
    Stockholm University.
    Does the seed bank contribute to the build-up of a genetic extinction debt in the grassland perennial Campanula rotundifolia?2017In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 120, no 3, p. 373-385Article in journal (Refereed)
    Abstract [en]

    Background and Aims: Habitat fragmentation threatens global biodiversity. Many plant species persist in habitat fragments via persistent life cycle stages such as seed banks, generating a species extinction debt. Here, seed banks are hypothesized to cause a temporal delay in the expected loss of genetic variation, which can be referred to as a genetic extinction debt, as a possible mechanism behind species extinction debts.

    Methods: Fragmented grassland populations of Campanula rotundifolia were examined for evidence of a genetic extinction debt, investigating if the seed bank contributed to the extinction debt build-up. The genetic make-up of 15 above- and below-ground populations was analysed in relation to historical and current levels of habitat fragmentation, both separately and combined.

    Key Results: Genetic diversity was highest in above-ground populations, though below-ground populations contained 8 % of unique alleles that were absent above-ground. Above-ground genetic diversity and composition were related to historical patch size and connectivity, but not current patch characteristics, suggesting the presence of a genetic extinction debt in the above-ground populations. No such relationships were found for the below-ground populations. Genetic diversity measures still showed a response to historical but not present landscape characteristics when combining genetic diversity of the above- and below-ground populations.

    Conclusions: The fragmented C. rotundifolia populations exhibited a genetic extinction debt. However, the role of the seed banks in the build-up of this extinction debt is probably small, since the limited, unique genetic diversity of the seed bank alone seems unable to counter the detrimental effects of habitat fragmentation on the population genetic structure of C. rotundifolia .

  • 13.
    Ramula, Satu
    et al.
    Södertörn University, Avdelning Naturvetenskap.
    Mutikainen, Pia
    Sex allocation of females and hermaphrodites in the gynodioecious Geranium sylvaticum2003In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 92, no 2, p. 207-213Article in journal (Refereed)
    Abstract [en]

    Seed production and patterns of sex allocation were studied in female and hermaphroditic plants in two gynodioecious populations of Geranium sylvaticum (Geraniaceae). Females produced more flower buds and seeds than hermaphrodites in one of the two study populations. The other female traits measured (pistil biomass, seed number per fruit, individual seed mass) did not differ between the gender morphs. The relative seed fitness of hermaphrodites differed between the study populations, with hermaphrodites gaining less of their fitness through female function in the population with a high frequency of females. However, the amount and size of pollen produced by hermaphrodites did not differ between populations. The number of flower buds was positively correlated with seed production in females, whereas in hermaphrodites a positive correlation between number of buds and seed production was found in only one of the two study populations. These results suggest that fitness gain through female function is labile in hermaphrodites of this species, and is probably affected by environmental factors such as the sex ratio of the population.

  • 14. Saheed, S. A.
    et al.
    Liu, L.
    Jonsson, Lisbeth
    Södertörn University, School of Life Sciences.
    Botha, C. E. J.
    Xylem - as well as phloem sustains severe damage due to feeding by the Russian wheat aphid2007In: South African Journal of Botany, ISSN 0254-6299, E-ISSN 1727-9321, Vol. 73, no 4, p. 593-599Article in journal (Refereed)
    Abstract [en]

    Investigation of comparative effects of feeding damage by the Russian wheat aphid (RWA, biotype SAI, Diuraphis noxia Mordvilko) on leaf blades of susceptible and resistant wheat cultivars (Triticum aestivum L. var Betta and Betta-Dn1 respectively) were carried out to establish the level of ultrastructural damage caused by this aphid and the possible limitation of damage induced which could be ascribed to the resistance gene Dn1 over the susceptible cultivar. Ultrastructurally, Betta-Dn1 sustained less damage to the vascular tissue as well as to the mesophyll during the experimental period. Both inter- and intracellular probes resulted in considerable saliva deposition as the aphids probed for suitable feeding sites. Salivary tracks were observed between and within mesophyll, bundle sheath cells as well as the vascular tissue, including the xylem. Disruption of organelles and cytoplasm resulted from cell probing and sheath deposition. Cell and organelle damage was more evident in the non-resistant Betta cultivar. The aphids probed for and fed from thin-walled sieve tubes preferentially. Few thick-walled sieve tubes showed evidence of either aphid probing or feeding-related damage. Saliva was deposited when the aphids probed inter- and intracellularly for feeding sites. The aphids appeared preferentially to probe for and feed from thin-walled sieve tubes, as few thick-walled sieve tubes showed evidence of damage. Vessels, apparently probed for water, contained watery saliva that encased the secondary walls and scaled pit membranes between probed vessels and xylem parenchyma. The xylem probed by the RWA was rendered non-functional, probably contributing to symptoms of leaf roll, chlorosis and necrosis, which were observed within two weeks of infestation in the susceptible Betta cultivar. This damage was limited in the resistant Betta-Dn] cultivar during the same time frame.

  • 15. Saheed, Sefiu A.
    et al.
    Jonsson, Lisbeth M. V.
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Botha, Christaan E. J.
    Russian wheat aphid causes greater reduction in phloem transport apacity of barley leaves than bird cherry-oat aphid.2010In: Acta Botanica Croatica, ISSN 0365-0588, E-ISSN 1847-8476, Vol. 69, no 1, p. 7-18Article in journal (Refereed)
    Abstract [en]

    The effects of feeding by the Russian wheat aphid (RWA). Dutraplu.s nom! ordvilko and the Bird cherry-oat aphid (BC A). Rhopaloppluan pad, L on he transport capacity of barley Holdeum vulgare L leaves were nvestigated and compated with a view to i-elan ng these effects to the isible symptoms shown by the respective infested plants RWA causes xtensive chlorosis and neciosis on an infested plant whereas I3CA auses no obseivable symptoms Our results using the xenobiotic. phloem obile Bum ophole. 5, 6 carboxyBurn escei n chacetate (5. 6-CFDA) evealed striking ch fletences in damage to the transpol t of ssimilates thiough the phloem by these two aphids The result clearly uggests that short-term feeding by RWA causes a reduction in tiansport f assimikites and a mole severe reduction oi pei haps even permanent essation of transport during long-term feed111,2. In contrast. feechntz y BCA does not lead to a !milked dect ease in transport do ring hort-term feeding period. howevei, a !eduction in the uanspoit was ecorded donne long-term feeding activities These iesults perhaps uggest that damage to ti ansport capacities of the barley leaves ppeals lobe partly responsible for the observed symptoms in WIA-infested plants and the lack of them during BCA in symptoms such as eduction ol cessation in transport of assionlates to growing tissues ay lead to such observable symptoms

  • 16. Saheed, Sefiu
    et al.
    Cierlik, Izabela
    Södertörn University, School of Life Sciences.
    Larsson, Kristina A. E.
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Delp, Gabriele
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Bradley, Graeme
    Jonsson, Lisbeth M. V.
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Botha, Christiaan E. J.
    Stronger induction of callose deposition in barley by Russian wheat aphid than bird cherry-oat aphid is not associated with differences in callose synthase or beta-1,3-glucanase transcript abundance2009In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 135, no 2, p. 150-161Article in journal (Refereed)
    Abstract [en]

    The effects of infestation by the bird cherry-oat aphid (BCA), (Rhopalosiphum padi L) and the Russian wheat aphid (RWA) (Diuraphis noxia Mordvilko) on callose deposition and transcription of genes related to callose accumulation were investigated in barley (Hordeum vulgare L. cv. Clipper). The BCA, which gives no visible symptoms, induced very limited callose deposition, even after 14 days of infestation. In contrast, RWA, which causes chlorosis, white and yellow streaking and leaf rolling, induced callose accumulation already after 24 h in longitudinal leaf veins. The deposition was pronounced after 72 h, progressing during 7 and 14 days of infestation. In RWA-infested source leaves, callose was also induced in longitudinal veins basipetal to the aphid-infested tissue, whereas in sink leaves, more callose deposition was found above the feeding sites. Eight putative callose synthase genes were identified in a database search, of which seven were expressed in the leaves, but with similar transcript accumulation in control and aphid-infested tissue. Five out of 12 examined beta-1,3-glucanases were expressed in the leaves. All five were upregulated in RWA-infested tissue, but only two in BCA-infested tissue, and to a lesser extent than by RWA. The results suggest that callose accumulation may be partly responsible for the symptoms resulting from RWA infestation and that a callose-inducing signal may be transported in the phloem. Furthermore, it is concluded that the absence of callose deposition in BCA-infested leaves is not because of a stronger upregulation of callose-degrading beta-1,3-glucanases in this tissue, as compared to RWA-infested leaves.

  • 17.
    Ström, Annika
    Södertörn University College, School of Discourse Studies, Rhetoric.
    Carl von Linné, Instruktion för resande naturforskare: [översättning från latin av Annika Ström]2007In: Naturalhistoria på resande fot: om att forska, undervisa och göra karriär i 1700-talets Sverige / [ed] Hanna Hodacs, Kenneth Nyberg, Stockholm: Nordic Academic Press , 2007, p. 199-210Chapter in book (Other academic)
  • 18.
    Ström, Annika
    Södertörn University College, School of Discourse Studies, Rhetoric.
    Carl von Linné, Om nödvändigheten av forskningsresor i fäderneslandet: [översättning från latin av Annika Ström]2007In: Naturalhistoria på resande fot: om att forska, undervisa och göra karriär i 1700-talets Sverige / [ed] Hanna Hodacs, Kenneth Nyberg, Stockholm: Nordic Academic Press , 2007, p. 183-198Chapter in book (Other academic)
  • 19. Ståhlberg, Sabira
    et al.
    Svanberg, Ingvar
    Sarana in Eurasian folk botany2006In: Suomalais-Ugrilaisen Seuran Aikakauskirja / Journal de la Société Finno-Ougrienne, ISSN 0355-0214, E-ISSN 1798-2987, no 91, p. 133-157Article in journal (Refereed)
  • 20.
    Svanberg, Ingvar
    Södertörn University, School of Gender, Culture and History, Study of religions.
    Plant Knowledge as Indicator of Historical Cultural Contacts: Tanning in the Atlantic Fringe2007In: Travelling Cultures and Plants: The Ethnobiology and Ethnopharmacy of Migrations / [ed] Andrea Pieroni, Ina Vandebroek, New York: Berghahn Books, 2007, p. 227-244Chapter in book (Refereed)
  • 21.
    Svanberg, Ingvar
    Södertörn University College, School of Gender, Culture and History, Study of religions.
    'The Lapps chew this Root a lot': Milk Parsley (Peucedanum palustre) in Sami Plant Knowledge2007In: Cultural interaction between east and west: archaeology, artefacts and human contacts in northern Europe / [ed] Ulf Fransson, Marie Svedin, Sophie Bergerbrant, Fedir Androshchuk, Stockholm: Stockholm University , 2007, p. 328-330Chapter in book (Refereed)
  • 22. Wrzaczek, Michael
    et al.
    Brosche, Mikael
    Salojarvi, Jarkko
    Kangasjarvi, Saijaliisa
    Idanheimo, Niina
    Mersmann, Sophia
    Robatzek, Silke
    Karpinski, Stanislaw
    Karpinska, Barbara
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Kangasjarvi, Jaakko
    Transcriptional regulation of the CRK/DUF26 group of Receptor-like rotein kinases by ozone and plant hormones in Arabidopsis2010In: BMC Plant Biology, ISSN 1471-2229, E-ISSN 1471-2229, Vol. 10, p. 95-Article in journal (Refereed)
    Abstract [en]

    Background: Plant Receptor-like/Pelle kinases (RLK) are a group of onserved signalling components that regulate developmental programs and esponses to biotic and abiotic stresses. One of the largest RLK groups s formed by the Domain of Unknown Function 26 (DUF26) RLKs, also called ysteine-rich Receptor-like Kinases (CRKs), which have been suggested to lay important roles in the regulation of pathogen defence and rogrammed cell death. Despite the vast number of RLKs present in lants, however, only a few of them have been functionally haracterized. esults: We examined the transcriptional regulation of all Arabidopsis RKs by ozone (O(3)), high light and pathogen/ elicitor reatment-conditions known to induce the production of reactive oxygen pecies (ROS) in various subcellular compartments. Several CRKs were ranscriptionally induced by exposure to O(3) but not by light stress. (3) induces an extracellular oxidative burst, whilst light stress leads o ROS production in chloroplasts. Analysis of publicly available icroarray data revealed that the transcriptional responses of the CRKs o O(3) were very similar to responses to microbes or athogen-associated molecular patterns (PAMPs). Several mutants altered n hormone biosynthesis or signalling showed changes in basal and (3)-induced transcriptional responses. onclusions: Combining expression analysis from multiple treatments with utants altered in hormone biosynthesis or signalling suggest a model in hich O(3) and salicylic acid (SA) activate separate signaling pathways hat exhibit negative crosstalk. Although O(3) is classified as an biotic stress to plants, transcriptional profiling of CRKs showed trong similarities between the O(3) and biotic stress responses.

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