354 research outputs found
The Pisum sativum SAD short-chain dehydrogenase/reductase: quinone reduction, tissue distribution, and heterologous expression
No full textThe pea (Pisum sativum) tetrameric short-chain alcohol dehydrogenase-like protein (SAD) family consists of at least three highly similar members (SAD-A, -B, and -C). According to mRNA data, environmental stimuli induce SAD expression (Brosché and Strid (1999) Plant Physiol 121: 479-487). The aim of this study was to characterize the SAD proteins by examining their catalytic function, distribution in pea, and induction in different tissues. In enzyme activity assays using a range of potential substrates, the SAD-C enzyme was shown to reduce one- or two-ring membered quinones lacking long hydrophobic hydrocarbon tails. Immunological assays using a specific antiserum against the protein, demonstrated that different tissues and cell types were shown to contain small amounts of SAD protein that was predominantly located within epidermal or sub-epidermal cells and around vascular tissue. Particularly high local concentrations were observed in the protoderm of the seed cotyledonary axis. Two bow-shaped rows of cells in the ovary and the placental surface facing the ovule also exhibited considerable SAD staining. UV-B irradiation led to increased staining in epidermal and sub-epidermal cells of leaves and stems. The different localization patterns of SAD suggest functions in both development and in responses to environmental stimuli. Finally, the pea SAD-C promoter was shown to confer heterologous wound-induced expression in Arabidopsis thaliana, which confirmed that the inducibility of its expression is regulated at the transcriptional level
Identification of a novel nuclear factor-binding site in the Pisum sativum sad gene promoters
No full textDNA 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
Ultraviolet-B radiation exposure lowers the antioxidant capacity in the Arabidopsis thaliana pdx1.3-1 mutant and leads to glucosinolate biosynthesis alteration in both wild type and mutant
No full textPyridoxine (vitamin B6) and its vitamers are used by living organisms both as enzymatic cofactors and as antioxidants. We used Arabidopsis pyridoxine biosynthesis mutant pdx1.3-1to study involvement of the PLP-synthase main polypeptide PDX1 in plant responses to ultraviolet radiation of two different qualities, one containing primarily UV-A (315-400 nm), the other containing both UV-A and UV-B (280-315 nm). The antioxidant capacity and the flavonoid and glucosinolate (GS) profiles were examined. As indicator of stress, Fv/Fmof photosystem II reaction centers was used. In pdx1.3-1, UV-A+B exposure led to a significant 5% decrease in Fv/Fmon the last day (day 15), indicating mild stress at this time point. Antioxidant capacity of Col-0 wildtype increased significantly (50-73%) after 1 and 3 days of UV-A+B. Instead, in pdx1.3-1, the antioxidant capacity significantly decreased by 44-52% over the same time period, proving the importance of a full complement of functional PDX1genes for detoxification of reactive oxygen species. There were no significant changes in flavonoid glycoside profile under any light condition. However, the GS profile was significantly altered, both with respect to Arabidopsis accession and exposure to UV. The difference in flavonoid and GS profiles reflect that the GS biosynthesis pathway contains at least one pyridoxine-dependent enzyme, whereas no such enzyme is used in flavonoid biosynthesis. Also, there was strong correlation between the antioxidant capacity and the content of some GS compounds. Our results show that vitamin B6vitamers, functioning both as antioxidants and co-factors, are of importance for physiological fitness of plants.Funding Agencies:Örebro University's Faculty for Business, Science and Technology Higher Education Institutional Excellence Programme of the Ministry of Human Capacities in Hungary 20765-3/2018/FEKUTSTRATResearch Area Plant Quality and Food Security at Leibniz-Institute of Vegetable and Ornamental Crops UV4qualit
Wood-inhabiting fungi of alder forests in north-central Scandinavia : 1, Aphyllophorales (Basidiomycetes). Taxonomy, ecology and distribution
No full textWood-inhabiting fungi were collected on different trees in 99 loca-' lities of alder woods, dominated by Alnus incana or occasionally A. glutinosa, in N-C Sweden and C Norway. Most of the localities are situated near the east coast of Sweden where the prevailing land elevation creates conditions suitable for colonization by alder. The remaining localities are mainly found in the inland parts of Sweden and Norway, along streams, in ravines etc. The investigated localities are briefly described as to their general vegetation, and a regional survey of the alder forests is given. The number of collections of Aphyllophorales amounts to approximately 5,000, comprising 286 species. The following new combinations are proposed: Hypoohnicium polonense (Bres.) Strid, H. pruinosum (Bres.) Strid, Phlebia lindtneri (Pil.) Parm. and Sistotrema hete- roncmum (John Erikss.) Strid. Seven species are collected as new to Scandinavia, viz., Botryobasidium aure urn3 Ceratobasidium stridiit Hyphoderma orphanellum, Hyphodontiella multiseptata, Hypoohnicium pruinosum> Phlebia lindtneri and Tubuliorinis effugiens, and approximately 85 additional species are reported for the first time from the investigation area. Six specimens of Cortioiaoeae have remained undetermined but are included in the species list. Most of them represent species new to science, but they are not, for different reasons, described as new species. Preliminary, one of them is referred to Ceratobasidium, one to Hyphoderma and two to Sistotrema. All species are presented in a list with annotations on their aut- ecology, distribution in Scandinavia and, when needed, taxonomy. The records of species collected more than once are mapped on 196 maps. The ecology of wood-inhabiting Aphyllophorales in alder forests is discussed, including habitat conditions (decay, moisture, temperature, soil conditions), distribution of fungi on different host trees, succession of fungi and some regional-ecological traits. The distribution of fungi is summarized by a grouping of representative species into flora elements which, in turn, are compared to those that have been proposed for vascular plants.Diss. Umeå : Umeå universitet, 1975digitalisering@um
Wood-inhabiting fungi of alder forests in north-central Scandinavia [Elektronisk resurs] : 1, Aphyllophorales (Basidiomycetes). Taxonomy, ecology and distribution
No full textWood-inhabiting fungi were collected on different trees in 99 loca-' lities of alder woods, dominated by Alnus incana or occasionally A. glutinosa, in N-C Sweden and C Norway. Most of the localities are situated near the east coast of Sweden where the prevailing land elevation creates conditions suitable for colonization by alder. The remaining localities are mainly found in the inland parts of Sweden and Norway, along streams, in ravines etc. The investigated localities are briefly described as to their general vegetation, and a regional survey of the alder forests is given.The number of collections of Aphyllophorales amounts to approximately 5,000, comprising 286 species. The following new combinations are proposed: Hypoohnicium polonense (Bres.) Strid, H. pruinosum (Bres.) Strid, Phlebia lindtneri (Pil.) Parm. and Sistotrema hete- roncmum (John Erikss.) Strid. Seven species are collected as new to Scandinavia, viz., Botryobasidium aure urn3 Ceratobasidium stridiit Hyphoderma orphanellum, Hyphodontiella multiseptata, Hypoohnicium pruinosum> Phlebia lindtneri and Tubuliorinis effugiens, and approximately 85 additional species are reported for the first time from the investigation area. Six specimens of Cortioiaoeae have remained undetermined but are included in the species list. Most of them represent species new to science, but they are not, for different reasons, described as new species. Preliminary, one of them is referred to Ceratobasidium, one to Hyphoderma and two to Sistotrema.All species are presented in a list with annotations on their aut- ecology, distribution in Scandinavia and, when needed, taxonomy. The records of species collected more than once are mapped on 196 maps.The ecology of wood-inhabiting Aphyllophorales in alder forests is discussed, including habitat conditions (decay, moisture, temperature, soil conditions), distribution of fungi on different host trees, succession of fungi and some regional-ecological traits.The distribution of fungi is summarized by a grouping of representative species into flora elements which, in turn, are compared to those that have been proposed for vascular plants.</p
Effect of UV-B radiation on morphology, phenolic compound production, gene expression, and subsequent drought stress responses in chili pepper (Capsicum annuum L.)
No full textIt has been suggested that accumulation of flavonoids could be a key step in development of plant tolerance to different environmental stresses. Moreover, it has been recognized that abiotic stresses such as drought and UV-B radiation (280-315 nm) induce phenolic compound accumulation, suggesting a role for these compounds in drought tolerance. The aim of the present study was to evaluate the effect of UV-B exposure on chili pepper (Capsicum annuum, cv. ‘Coronel’) plant performance, phenolic compound production, and gene expression associated with response to subsequent drought stress. Additionally, the phenotypic response to drought stress of these plants was studied. UV-B induced a reduction both in stem length, stem dry weight and number of floral primordia. The largest reduction in these variables was observed when combining UV-B and drought. UV-B-treated well-watered plants displayed fructification approximately 1 week earlier than non-UV-B-treated controls. Flavonoids measured epidermally in leaves significantly increased during UV-B treatment. Specifically, UV-B radiation significantly increased chlorogenic acid and apigenin 8-C-hexoside levels in leaves and a synergistic increase of luteolin 6-C-pentoside-8-C-hexoside was obtained by UV-B and subsequent drought stress. Gene expression of phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) genes also increased during UV-B treatments. On the other hand, expression of genes related to an oxidative response, such as mitochondrial Mn-superoxide dismutase (Mn-SOD) and peroxidase (POD) was not induced by UV-B. Drought stress in UV-B-treated plants induced mitochondrial Mn-SOD gene expression. Taken together, the UV-B treatment did not induce significant tolerance in plants towards drought stress under the conditions used.</p
Knowledge for knowledge’s sake : Personal thoughts on Professor Lars Olof Björn’s impact on plant UV photobiology and on Swedish popular science over the last three decades (at least)
No full textTrois Constructions a Dependance Entre Sujet Et <i>PP</i>
No full textKjell-Åke Gunnarson: Three Constructions with a Dependency between Subject and PP.
This study bears on relations between subject noun phrases and prepositional phrases found in various positions. The author discusses the action of a rule that extraposes noun complements of the subject head. Thus prepositional phrases are moved to positions that superficially appear as complement position. Complex conditions on the application of the rule lead to the distinction of three types of constructions that depend both on the main verb and on the content of the noun phrases.</jats:p
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