| 1. |
- Sävenstrand, Helena, et al.
(author)
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A Pisum sativum glyoxysomal malate dehydrogenase induced by cadmium exposure
- 2004
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In: DNA Sequence. - : Informa UK Limited. - 1042-5179 .- 1029-2365. ; 15:3, s. 206-208
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Journal article (peer-reviewed)abstract
- The glyoxysomal malate dehydrogenase (gMDH) catalyses the formation of oxaloacetate from malate during beta-oxidation of fatty acids in the glyoxysome. A partial Pisum sativum L. (cv. Greenfeast) cDNA was first isolated from a suppression subtractive hybridisation cDNA library obtained from heavy metal stressed plants. The full length cDNA was then isolated by rapid amplification of cDNA ends. The translated sequence showed strong similarity to Cucumis sativus and Citrullus lanatus gMDH including a typical glyoxysome-targeting presequence comprising the PTS2 motif and a cleavage site for a cystein-directed protease. Exposure of pea plants to Cd2+ induced expression of the gMDH gene in mature pea leaves indicating that the enzyme is under environmental control in addition to the normal developmental regulation pattern.
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| 2. |
- Sävenstrand, Helena, et al.
(author)
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Induction of early light-inducible protein gene expression in Pisum sativum after exposure to low levels of UV-B irradiation and other environmental stresses
- 2004
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In: Plant Cell Reports. - : Springer Science and Business Media LLC. - 0721-7714 .- 1432-203X. ; 22:7, s. 532-536
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Journal article (peer-reviewed)abstract
- Plants are constantly subjected to environmental changes and have developed various defence mechanisms to facilitate their continued existence. Pisum sativum plants were exposed to low levels of UV-B radiation and ELIP (early light-inducible proteins) mRNA, with a probable protective function, was rapidly and strongly induced during this type of stress. To our knowledge, this is the only photosynthetic gene that is up-regulated following exposure to UV-B, and this result has to be compared with studies predominantly reporting down-regulation by UV-B of genes encoding proteins localised in the plastid. The expression pattern of ELIP mRNA in pea was also investigated during salt, wounding and ozone stress. The transcript levels of ELIP were induced after the salt and wounding treatments but not during ozone fumigation.
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| 3. |
- Sävenstrand, Helena, et al.
(author)
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Six genes strongly regulated by mercury in Pisum sativum roots
- 2004
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In: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 42:2, s. 135-142
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Journal article (peer-reviewed)abstract
- Suppression subtractive hybridisation was used to isolate heavy metal-induced genes from Pisum sativum roots hydroponically exposed to 5 microM HgCl2 and 10 microM EDTA. Six genes were induced out of which one, PsHMIP6B, was novel. The other genes (PsSAMT, PsI2'H, PsNDA, PsAPSR, PsPOD) had not previously been isolated from pea and sequenced. All six genes were also induced after exposure to 5 microM HgCl2 in the absence of EDTA. The induction pattern was in some cases different for the two Hg species, demonstrating a quicker response to-free Hg2+ than Hg-EDTA. The stress-specificity of the gene regulation was investigated by hydroponically adding 5 microM Cd2+. Most Hg-induced cDNAs were also induced by Cd2+ but to a smaller extent than after Hg exposure. In addition, the gene expression was also probed for tissue specificity, which showed that all six genes were expressed in roots and not in leaves.
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| 4. |
- Sävenstrand, Helena, et al.
(author)
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Ultraviolet-B signalling : Arabidopsis brassinosteroid mutants are defective in UV-B regulated defence gene expression
- 2004
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In: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 42:9, s. 687-694
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Journal article (peer-reviewed)abstract
- The involvement of brassinosteroids in signalling events in plants during UV-B stress (280-315 nm) was investigated in Arabidopsis thaliana. Brassinosteroids are involved in growth and development in plants and have also been shown to enhance stress tolerance. Three mutants deficient in the biosynthetic pathway of brassinolide (BL; det2, dim1 and cpd) and the BL insensitive mutant (bri1) were together with visible light irradiated with 3 or 9 h of UV-B radiation (biologically effective radiation normalised to 300 nm being 0.24 W m(-2)). Also, a small size control, irx1, and Columbia 0 (Col-0) wild-type plants were examined under identical conditions. Gene expression patterns were established for these mutants with a set of four molecular markers (the defence genes chalcone synthase (CHS), PYROA, pathogenesis-related protein PR-5, and a gene regulated by very low levels of UV-B, MEB5.2). Although the genes in the brassinodefective mutants were still induced by UV-B radiation, they all also showed reduced levels of mRNA transcripts compared with Col-0 and irx1. The bri1 and cpd were the mutants with lowest levels of molecular marker mRNA transcripts. The effects of impairment of brassinosteroid signalling also differed between the genes studied, indicating a need for a complete brassinosteroid pathway in UV-B signalling.
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| 5. |
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| 6. |
- Brosché, Mikael, et al.
(author)
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Gene regulation by low level UV-B radiation : identification by DNA array analysis
- 2002
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In: Photochemical and Photobiological Sciences. - 1474-905X .- 1474-9092. ; 1:9, s. 656-664
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Journal article (peer-reviewed)abstract
- UV-B radiation alters transcript levels of various defence genes and photosynthetic genes in plants. Utilising a DNA array with 5000 ESTs and cDNAs from Arabidopsis thaliana, 70 genes were found to show a greater than two-fold induction or repression of transcript levels. Six genes (MEB5.2, PyroA, Ubq3, Lhcb6, F5D21.10 and the gene for an RNA polymerase II subunit) were tested for stress specific gene regulation on northern blots with RNA from plants exposed to low dose UV-B radiation, ozone or wounding. Transcript levels for PyroA, Uhq3 and the gene for a RNA polymerase II subunit were all specifically increased by UV-B. MEB5.2 mRNA levels also rose, whereas Lhcb6 and FSD21.10 transcript levels decreased under all stresses. The PyroA gene product in fungi is needed for biosynthesis of pyridoxine, and might have a role in protection against singlet oxygen. The Ubq3 gene encodes the ubiquitin protein that is attached to proteins destined for degradation. MEB5.2 and F5D21.10 represent novel gene products whose function have not yet been identified. Pairwise comparisons between the UV-B inducible promoters have identified a series of elements present in the MEB5.2 and PyroA promoters, absent from promoters of genes for early phenylpropanoid metabolism and that may be responsible for modulating their UV-B responses.
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| 7. |
- Brosché, Mikael, et al.
(author)
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Molecular events following perception of ultraviolet-B radiation by plants
- 2003
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In: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 117:1, s. 1-10
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Journal article (peer-reviewed)abstract
- Exposure of plants to UV-B radiation (280–320 nm) results in changes in expression of a large number of genes. Before UV-B radiation or light of other wavelengths can give rise to a cellular response, it has to be perceived by some kind of receptor, and the information transduced via a signalling pathway to the target molecules, be it proteins in the cytoplasm or the genetic material in the nucleus. The perception of low levels of UV-B probably occurs via a UV-B photoreceptor followed by several different signalling pathways. These pathways include second messengers such as calcium, kinases and the catalytic formation of reactive oxygen species. High levels of UV-B, on the other hand, probably cause cellular damage and oxidative stress, thus activating a general stress signal transduction pathway which leads to a response similar to that which occurs after pathogen attack and other stresses. Some of the genes identified so far as being regulated by UV-B encode proteins involved in the biosynthesis of protective pigments, DNA repair and antioxidative enzymes, photosynthetic genes, cell cycle genes, and stress genes induced by other types of stimuli (i.e. pathogenesis-related proteins and senescence-induced genes). In the light of the information obtained on components necessary for UV-B-induced changes in gene expression, we propose in this mini-review a working model for UV-B perception and signal transduction. This model also takes into account dosage differences for the observations, which imply a separation into UV-B-specific and more general stress signal transduction.
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| 8. |
- Gittins, John R., et al.
(author)
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Identification of a novel nuclear factor-binding site in the Pisum sativum sad gene promoters
- 2002
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In: Biochimica et Biophysica Acta, Gene Structure and Expression. - 0167-4781 .- 1879-2634. ; 1574:3, s. 231-244
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Journal article (peer-reviewed)abstract
- DNA fragments containing the 5' promoter regions of the Pisum sativum sadA and sadC genes were amplified from genomic DNA, cloned and sequenced. These sequences contain a number of conserved cis-acting elements, which are potentially involved in stress-induced transcription of the sad genes. To determine whether any of the identified elements are active in binding nuclear factors in vitro, 11 60-bp overlapping (by 30 bp) DNA probe fragments covering the proximal sadC promoter sequence (360 bp) were used in electrophoretic mobility shift assays with competition. Binding activities were compared in nuclear extracts from control, UV-B-stressed and wounded pea leaves. The pattern of DNA binding was almost identical with all three extracts, with one 30-bp region being the predominant site for factor binding. Using overlapping sub-fragments of this region, the majority of the specific binding could be attributed to the novel 11-bp GC-rich sequence GTGGCGCCCAC. An almost identical sequence is conserved in the sadA promoter. This motif has features in common with a number of recognised cis-elements, which suggests a possible binding site for factors which play a role in regulating sad gene transcription.
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| 9. |
- Kalbin, Georgi, et al.
(author)
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UV-B-induced DNA damage and expression of defence genes under UV-B stress : tissue-specific molecular marker analysis in leaves
- 2001
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In: Plant, Cell and Environment. - : Wiley. - 0140-7791 .- 1365-3040. ; 24:9, s. 983-990
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Journal article (peer-reviewed)abstract
- The aim of this study was to investigate the regulatory effect of ultraviolet-B (UV-B) radiation on a number of key stress response genes found in the epidermis and mesophyll of Pisum sativum L., Argenteum mutant. This mutant was chosen for the ease with which the entire epidermis can be removed from the mesophyll tissue. An additional goal was to explore the potential modifying effect of pre-acclimation of plants to UV-B radiation prior to exposure by UV-B during treatment. Results showed that mRNA accumulation was similar during acute short-term UV-B exposure for chalcone synthase (Chs) and short-chain alcohol dehydrogenase (SadA) in both epidermis and mesophyll. In contrast, the mRNA levels differed considerably between tissues for phenylalanine ammonia lyase, chalcone isomerase and lipid transfer protein. After 24 h incubation in visible light after cessation of UV-B exposure, the regulation of mRNA levels also differed between Chs and SadA, the former showing no expression in the epidermis and the latter none in the mesophyll. Acclimation to low UV-B levels before acute exposures resulted in delayed induction of Chs and SadA. Measurements of UV-B-induced cyclobutane pyrimidine dimers (CPDs) showed a greater formation in epidermis than in mesophyll. In addition, acclimation at low UV-B levels resulted in significantly higher basal levels of CPDs than in non-acclimated plants in both mesophyll and epidermis and also in increased damage in concomitant acute exposures. The lack of correlation between the number of CPDs and levels of transcripts for defence genes, indicates that DNA damage does not control transcription of these genes.
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| 10. |
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