| 1. |
- Ahlfors, Reetta, et al.
(författare)
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Arabidopsis RADICAL-INDUCED CELL DEATH1 belongs to the WWE protein-protein interaction domain protein family and modulates abscisic acid, ethylene, and methyl jasmonate responses.
- 2004
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Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 16:7, s. 1925-37
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Tidskriftsartikel (refereegranskat)abstract
- Experiments with several Arabidopsis thaliana mutants have revealed a web of interactions between hormonal signaling. Here, we show that the Arabidopsis mutant radical-induced cell death1 (rcd1), although hypersensitive to apoplastic superoxide and ozone, is more resistant to chloroplastic superoxide formation, exhibits reduced sensitivity to abscisic acid, ethylene, and methyl jasmonate, and has altered expression of several hormonally regulated genes. Furthermore, rcd1 has higher stomatal conductance than the wild type. The rcd1-1 mutation was mapped to the gene At1g32230 where it disrupts an intron splice site resulting in a truncated protein. RCD1 belongs to the (ADP-ribosyl)transferase domain–containing subfamily of the WWE protein–protein interaction domain protein family. The results suggest that RCD1 could act as an integrative node in hormonal signaling and in the regulation of several stress-responsive genes.
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| 2. |
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| 3. |
- Brosché, Mikael, et al.
(författare)
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Gene regulation by low level UV-B radiation : identification by DNA array analysis
- 2002
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Ingår i: Photochemical and Photobiological Sciences. - 1474-905X .- 1474-9092. ; 1:9, s. 656-664
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Brosché, Mikael, et al.
(författare)
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Molecular events following perception of ultraviolet-B radiation by plants
- 2003
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 117:1, s. 1-10
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Kalbin, Georgi, et al.
(författare)
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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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Ingår i: Plant, Cell and Environment. - : Wiley. - 0140-7791 .- 1365-3040. ; 24:9, s. 983-990
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Strid, Åke, et al.
(författare)
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Opportunities to genetically modify plants to cope with environmental stress
- 2001
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Ingår i: British Food Journal. - : Emerald. - 0007-070X .- 1758-4108. ; 103:11, s. 796-800
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Tidskriftsartikel (refereegranskat)abstract
- Discusses the responses of plants to a variety of environmental stresses and considers different techniques that could potentially be used to detect and amplify such responses. Because plants may naturally produce steroids in response to raised stress levels, the paper suggests that genetic modification of crop plants to improve resistance to stress is worth investigating as a strategy. Sensitive to public concerns about the safety of transgenic crops, the authors suggest using such plants in carefully controlled locations.
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| 7. |
- Sävenstrand, Helena, et al.
(författare)
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Regulation of gene expression by low levels of ultraviolet-B radiation in Pisum sativum : isolation of novel genes by suppression subtractive hybridisation
- 2002
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Ingår i: Plant and Cell Physiology. - : Oxford University Press (OUP). - 0032-0781 .- 1471-9053. ; 43:4, s. 402-410
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Tidskriftsartikel (refereegranskat)abstract
- Suppression subtractive hybridisation was used to isolate genes differentially regulated by low levels (UV-B(BE,300) 0.13 W m(-2)) of ultraviolet-B radiation (UV-B; 290-320 nm) in Pisum sativum. Six genes were regulated, two of which were novel. The mRNA levels for these two (PsTSDC and PsUOS1) were increased and depressed by UV-B treatment, respectively. Domains in the PsTSDC translation product was similar to TIR (Toll-Interleukin-1 receptor-similar) domains and a NB-ARC domain (nucleotide-binding domain in APAF-1, R gene products and CED-4). The PsUOS1 translation product was similar to an open reading frame in Arabidopsis. Genes encoding embryo-abundant protein (PsEMB) and S-adenosyl-L-methionine synthase (PsSAMS) were induced by UV-B, whereas the transcript levels for genes encoding sucrose transport protein (PsSUT) or ribulose-5-phosphate 3-epimerase (PsR5P3E) were decreased. These regulation patterns are novel, and the PsEMB and PsR5P3E sequences are reported for the first time. The stress-specificity of regulation of these genes were tested by ozone fumigation (100 ppb O(3)). Qualitatively, the similarity of expression after both UV-B and ozone exposure suggests that, for these genes, similar stress-response pathways are in action.
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| 8. |
- Sävenstrand, Helena, et al.
(författare)
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Ultraviolet-B signalling : Arabidopsis brassinosteroid mutants are defective in UV-B regulated defence gene expression
- 2004
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Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 42:9, s. 687-694
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Tidskriftsartikel (refereegranskat)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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