Åke Strid | Örebro University (original) (raw)

Papers by Åke Strid

Plant and Cell Physiology, Sep 1, 1993

Plant Biotechnology Journal, May 1, 2020

Flavonoid accumulation in most fruits is enhanced by ethylene and jasmonate. However, little is k... more Flavonoid accumulation in most fruits is enhanced by ethylene and jasmonate. However, little is known about the hormone functions related to red pear fruit coloration or their combined effects and potential underlying mechanisms. Various treatments were used to investigate the flavonoid metabolite profile and pear transcriptome to verify the effects of ethylene and jasmonate on flavonoid biosynthesis in red pear fruits as well as the mechanism behind this. Ethylene inhibits anthocyanin biosynthesis in red Chinese pear fruits, whereas jasmonate increases anthocyanin and flavone/isoflavone biosyntheses. The branching of the jasmonateinduced flavonoid biosynthesis pathway is determined by ethylene. Co-expression network and Mfuzz analyses revealed 4,368 candidate transcripts. Additionally, ethylene suppresses PpMYB10 and PpMYB114 expression via TF repressors, ultimately decreasing anthocyanin biosynthesis. Jasmonate induces anthocyanin accumulation through transcriptional or posttranslational regulation of TFs-like MYB and bHLH in the absence of ethylene. However, jasmonate induces ethylene biosynthesis and the associated signalling pathway in pear, thereby decreasing anthocyanin production, increasing the availability of the precursors for flavone/ isoflavone biosynthesis and enhancing deep yellow fruit coloration. We herein present new phenotypes and fruit coloration regulatory patterns controlled by jasmonate and ethylene, and confirm that the regulation of fruit coloration is complex.

The following experimental techniques were used to determine the structure: X-RAY DIFFRACTION The... more The following experimental techniques were used to determine the structure: X-RAY DIFFRACTION The reported resolution of this entry is 1.65 Å. Percentile scores (ranging between 0-100) for global validation metrics of the entry are shown in the following graphic. The table shows the number of entries on which the scores are based. Metric Whole archive (#Entries) Similar resolution (#Entries, resolution range(Å)

The F-type ATP synthase supplies the cell with ATP using the energy from proton gradients across ... more The F-type ATP synthase supplies the cell with ATP using the energy from proton gradients across membranes to phosphorylate ADP. The F1 catalytic subunit consists of five subunits: α, β, γ, δ and e. The genes encoding these subunits in bacteria are clustered in one operon, called the atp operon. The conserved gene order in the atp operons of chloroplasts, Escherichia coli, Rhodospirillum rubrum, Rhodobacter blasticus and some cyanobacteria, indicates common ancestry [1]. An interesting feature of the Rb. blasticus atp operon is that a sixth gene, termed URF6, is placed between the genes for the γ and β subunits [2]. Since the genes of the atp operon are co-transcribed, the URF6 gene product may be involved in the ATP synthase. Previously, we have raised antibodies towards the URF6 gene product, and used them to investigate the presence of this protein in several other bacteria and during purification of the overexpressed recombinant protein [3]. Our studies indicate that Paracoccus denitrificans also appears to contain this protein. In the present study we have used a PCR-based method and Southern blotting to investigate if the URF6 gene is present in P. denitrificans and Rhodobacter sphaeroides and to determine its location in the genome. The PCR strategy used primers designed from conserved regions at the end of the atpG gene (γ) and beginning of the atpD gene (β). PCR products with the expected sizes were cloned and sequenced.

Apmis, Nov 18, 2016

The asymptomatic nature of most Chlamydia trachomatis infections and the lack of appropriate effe... more The asymptomatic nature of most Chlamydia trachomatis infections and the lack of appropriate effects by current prevention and management call for vaccine development. We evaluated a recombinant subunit vaccine candidate based on the major outer membrane protein variable segments 2 and 4 (MOMP VS2/4). To achieve maximal immunogenicity and ease of production and purification, MOMP VS2/4 was constructed by using highly immunogenic sequences of MOMP only, thereby minimizing the presence of hydrophobic regions, and spacing the immunogenic epitopes with a flexible amino acid sequence. A purification tag was also added. The MOMP VS2/4 was given intranasally, with or without intravaginal boost, with cholera toxin (CT) adjuvant to C57BL/6 mice, which were screened for immunogenicity and protection against a live challenge infection with C. trachomatis serovar D. Bacterial shedding, cell-mediated responses, and antibody responses were monitored. Immunized mice exhibited significantly less bacterial shedding and were better protected against infertility as compared to unimmunized control mice. Immunizations stimulated both systemic and local specific antibody (IgG1, IgG2c, and IgA) responses, and primed T cells that produced interferon-γ and interleukins 13 and 17 upon challenge with recall antigen. Thus, MOMP VS2/4, in combination with CT adjuvant, stimulated Th1, Th2, and Th17 effector cells, and generated protective immunity associated with less pathology. We regard MOMP VS2/4 as a promising candidate for further development into a mucosal chlamydial vaccine.

Journal of Chemical Information and Modeling, May 24, 2011

A homology model of the Arabidopsis thaliana UV resistance locus 8 (UVR8) protein is presented he... more A homology model of the Arabidopsis thaliana UV resistance locus 8 (UVR8) protein is presented herein, showing a seven-bladed β-propeller conformation similar to the globular structure of RCC1. The UVR8 amino acid sequence contains a very high amount of conserved tryptophans, and the homology model shows that seven of these tryptophans cluster at the 'top surface' of the UVR8 protein where they are intermixed with positive residues (mainly arginines) and a couple of tyrosines. Quantum chemical calculations of excitation spectra of both a large cluster model involving all twelve above-mentioned residues and smaller fragments thereof reveal that absorption maxima appearing in the 280-300 nm range for the full cluster result from interactions between the central tryptophans and surrounding arginines. This observation coincides with the published experimentally measured action spectrum for the UVR8-dependent UV-B stimulation of HY5 transcription in mature A. thaliana leaf tissue. In total these findings suggest that UVR8 has in fact in itself the ability to be an ultraviolet-B photoreceptor in plants.

Journal of Physical Chemistry B, Jun 26, 2009

Molecules acting as antioxidants capable of scavenging reactive oxygen species (ROS) are of the u... more Molecules acting as antioxidants capable of scavenging reactive oxygen species (ROS) are of the utmost importance in the living cell. The antioxidative properties of pyridoxine (vitamin B 6) have recently been discovered. Previous theoretical calculations have shown a high reactivity of pyridoxine toward hydroxyl radicals, where the latter preferably abstract H from either carbon of the two methanol substituents (C8 or C9). In this study, we have explored the reactivity of pyridoxine toward further hydroxyl radicals, considering as the first step the H abstraction from either C8 or C9, also including addition reactions and cyclization. Many of the reactions display similar ∆G, and hence, the quenching of hydroxyl radicals by pyridoxine may undergo different pathways leading to a mix of products. In addition, we observe that pyridoxine, under high hydroxyl radical concentrations, may scavenge up to eight radicals, supporting its observed high antioxidant activity.

Plant and Cell Physiology, Oct 1, 1992

Frontiers in Plant Science, Jan 5, 2021

Ultraviolet B (UV-B) (280-315 nm) and ultraviolet A (UV-A) (315-400 nm) radiation comprise small ... more Ultraviolet B (UV-B) (280-315 nm) and ultraviolet A (UV-A) (315-400 nm) radiation comprise small portions of the solar radiation but regulate many aspects of plant development, physiology and metabolism. Until now, how plants respond to UV-B in the presence of different light qualities is poorly understood. This study aimed to assess the effects of a low UV-B dose (0.912 ± 0.074 kJ m −2 day −1 , at a 6 h daily UV exposure) in combination with four light treatments (blue, green, red and broadband white at 210 µmol m −2 s −1 Photosynthetically active radiation [PAR]) on morphological and physiological responses of cucumber (Cucumis sativus cv. "Lausanna RZ F1"). We explored the effects of light quality backgrounds on plant morphology, leaf gas exchange, chlorophyll fluorescence, epidermal pigment accumulation, and on acclimation ability to saturating light intensity. Our results showed that supplementary UV-B significantly decreased biomass accumulation in the presence of broad band white, blue and green light, but not under red light. UV-B also reduced the photosynthetic efficiency of CO 2 fixation (α) when combined with blue light. These plants, despite showing high accumulation of anthocyanins, were unable to cope with saturating light conditions. No significant effects of UV-B in combination with green light were observed for gas exchange and chlorophyll fluorescence parameters, but supplementary UV-B significantly increased chlorophyll and flavonol contents in the leaf epidermis. Plants grown under red light and UV-B significantly increased maximum photosynthetic rate and dark respiration compared to pure red light. Additionally, red and UV-B treated plants exposed to saturating light intensity showed higher quantum yield of photosystem II (PSII), fraction of open PSII centres and electron transport rate and showed no effect on the apparent maximum quantum efficiency of PSII photochemistry (F v /F m) or non-photochemical quenching, in contrast to solely red-light conditions. These findings provide new insights into how plants respond to UV-B radiation in the presence of different light spectra.

Physiologia Plantarum, Sep 23, 2021

During recent years, we have advanced our understanding of plant molecular responses to ultraviol... more During recent years, we have advanced our understanding of plant molecular responses to ultraviolet radiation (UV, 280–400 nm); however, how plants respond to UV radiation under different spectral light qualities is poorly understood. In this study, cucumber plants (Cucumis sativus “Lausanna RZ F1”) were grown under monochromatic blue, green, red, and broadband white light in combination with UV radiation. The effects of light quality and UV radiation on acclimatory responses were assessed by measuring transcript accumulation of ELONGATED HYPOCOTYL 5 (HY5), CHALCONE SYNTHASE 2 (CHS2), and LIGHT HARVESTING COMPLEX II (LHCII), and the accumulation of flavonoids and hydroxycinnamic acids in the leaves. The growth light backgrounds differentially regulated gene expression and metabolite accumulation. While HY5 and CHS2 transcripts were induced by blue and white light, LHCII was induced by white and red light. Furthermore, UV radiation antagonized the effects of blue, red, green, and white light on transcript accumulation in a gene‐dependent manner. Plants grown under blue light with supplementary UV radiation increased phenylalanine, flavonol disaccharide I and caffeic acid contents compared to those exposed only to blue light. UV radiation also induced the accumulation of flavonol disaccharide I and II, ferulic acid hexose and coumaric acid hexose in plants grown under green light. Our findings provide a further understanding of plant responses to UV radiation in combination with different light spectra and contribute to the design of light recipes for horticultural practices that aim to modify plant metabolism and ultimately improve crop quality.

Plant Physiology, Oct 1, 1999

A pea (Pisum sativum) DNA fragment (termed MB3) was isolated by differential display of cDNAs obt... more A pea (Pisum sativum) DNA fragment (termed MB3) was isolated by differential display of cDNAs obtained from total leaf RNA of ultraviolet B (UV-B) radiation-treated plants. Longer cDNAs were cloned by rapid amplification of cDNA ends in the 3 to 5 direction. Three different, but very similar, cDNAs were cloned, sadA, sadB, and sadC, the major difference between them being a 36-bp deletion in the coding region of sadB. Southern blotting confirmed the occurrence of at least three genes in the pea genome. Database comparisons of the SAD protein sequences revealed high identity (46%) and similarity (77%) with a putative tomato (Lycopersicon esculentum) short-chain alcohol dehydrogenase. Very low levels of UV-B radiation (the biologically effective radiation normalized to 300 nm ‫؍‬ 0.08 W m ؊2) was shown to up-regulate expression, a dose considerably lower than that needed to induce expression of the well-known UV-B defensive chalcone synthase and phenylalanine ammonia lyase genes. RNase protection assay revealed that primarily sadA and sadC mRNA accumulation was enhanced by UV-B. In addition to UV-B irradiation, ozone fumigation, wounding, aluminum stress, and salt stress induced increased transcript levels of the sad genes in pea.

Vaccines, Oct 6, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Photochemical & Photobiological Sciences

SSRN Electronic Journal, 2022

The F-type ATP synthase supplies the cell with ATP using the energy from proton gradients across ... more The F-type ATP synthase supplies the cell with ATP using the energy from proton gradients across membranes to phosphorylate ADP. The F1 catalytic subunit consists of five subunits: α, β, γ, δ and e. The genes encoding these subunits in bacteria are clustered in one operon, called the atp operon. The conserved gene order in the atp operons of chloroplasts, Escherichia coli, Rhodospirillum rubrum, Rhodobacter blasticus and some cyanobacteria, indicates common ancestry [1]. An interesting feature of the Rb. blasticus atp operon is that a sixth gene, termed URF6, is placed between the genes for the γ and β subunits [2]. Since the genes of the atp operon are co-transcribed, the URF6 gene product may be involved in the ATP synthase. Previously, we have raised antibodies towards the URF6 gene product, and used them to investigate the presence of this protein in several other bacteria and during purification of the overexpressed recombinant protein [3]. Our studies indicate that Paracoccus ...

In greenhouses, crops are protected from adverse weather conditions allowing year-round productio... more In greenhouses, crops are protected from adverse weather conditions allowing year-round production. However, this comes with a trade-off, which is the lack of UV-A and UV-B exposure. Excess of UV impairs plant growth and nutrient absorption, while lack of UV in greenhouses reduce the synthesis of metabolites associated with nutritional and sensorial quality of plants. Here, we provide insights into how the application of sensomics, an approach that combines top-down system biology approaches, such as metabolomics, with sensory science, can help to bridge the gap between plant science and horticultural quality.

We previously showed that UV-B can increase metabolic hydrogen peroxide (H2O2)concentrations in l... more We previously showed that UV-B can increase metabolic hydrogen peroxide (H2O2)concentrations in leaves and that it is able to convert H2O2 to hydroxyl radicals (•OH) (Czegeny et al. 2014). Thus, efficient scavenging of H2O2 and •OH are expected to be important aspects in a successful acclimation to UV-B. Vitamin B6 has an essential role both in plant development and stress tolerance (Raschke et al. 2011). In addition to their coenzyme function in several biosynthetic pathways (Drewke and Leistner 2001), B6 derivates are potent quenchers of ROS(Havaux et al. 2009, Matxain et al. 2009). In this study, we used Arabidopsis thaliana mutants (rsr4-1) reduced in B6 biosynthesis (Wagner et al. 2006) to investigate how vitamin B6 derivates of contribute to the plants’ acclimation to supplemental UV-B in growth chambers. In response to UV-B both mutant and wild type (C24) leaves altered their antioxidant profiles – including increases in B6 derivates. Wild type plants avoided oxidative stress...

Plant and Cell Physiology, Sep 1, 1993

Plant Biotechnology Journal, May 1, 2020

Flavonoid accumulation in most fruits is enhanced by ethylene and jasmonate. However, little is k... more Flavonoid accumulation in most fruits is enhanced by ethylene and jasmonate. However, little is known about the hormone functions related to red pear fruit coloration or their combined effects and potential underlying mechanisms. Various treatments were used to investigate the flavonoid metabolite profile and pear transcriptome to verify the effects of ethylene and jasmonate on flavonoid biosynthesis in red pear fruits as well as the mechanism behind this. Ethylene inhibits anthocyanin biosynthesis in red Chinese pear fruits, whereas jasmonate increases anthocyanin and flavone/isoflavone biosyntheses. The branching of the jasmonateinduced flavonoid biosynthesis pathway is determined by ethylene. Co-expression network and Mfuzz analyses revealed 4,368 candidate transcripts. Additionally, ethylene suppresses PpMYB10 and PpMYB114 expression via TF repressors, ultimately decreasing anthocyanin biosynthesis. Jasmonate induces anthocyanin accumulation through transcriptional or posttranslational regulation of TFs-like MYB and bHLH in the absence of ethylene. However, jasmonate induces ethylene biosynthesis and the associated signalling pathway in pear, thereby decreasing anthocyanin production, increasing the availability of the precursors for flavone/ isoflavone biosynthesis and enhancing deep yellow fruit coloration. We herein present new phenotypes and fruit coloration regulatory patterns controlled by jasmonate and ethylene, and confirm that the regulation of fruit coloration is complex.

The following experimental techniques were used to determine the structure: X-RAY DIFFRACTION The... more The following experimental techniques were used to determine the structure: X-RAY DIFFRACTION The reported resolution of this entry is 1.65 Å. Percentile scores (ranging between 0-100) for global validation metrics of the entry are shown in the following graphic. The table shows the number of entries on which the scores are based. Metric Whole archive (#Entries) Similar resolution (#Entries, resolution range(Å)

The F-type ATP synthase supplies the cell with ATP using the energy from proton gradients across ... more The F-type ATP synthase supplies the cell with ATP using the energy from proton gradients across membranes to phosphorylate ADP. The F1 catalytic subunit consists of five subunits: α, β, γ, δ and e. The genes encoding these subunits in bacteria are clustered in one operon, called the atp operon. The conserved gene order in the atp operons of chloroplasts, Escherichia coli, Rhodospirillum rubrum, Rhodobacter blasticus and some cyanobacteria, indicates common ancestry [1]. An interesting feature of the Rb. blasticus atp operon is that a sixth gene, termed URF6, is placed between the genes for the γ and β subunits [2]. Since the genes of the atp operon are co-transcribed, the URF6 gene product may be involved in the ATP synthase. Previously, we have raised antibodies towards the URF6 gene product, and used them to investigate the presence of this protein in several other bacteria and during purification of the overexpressed recombinant protein [3]. Our studies indicate that Paracoccus denitrificans also appears to contain this protein. In the present study we have used a PCR-based method and Southern blotting to investigate if the URF6 gene is present in P. denitrificans and Rhodobacter sphaeroides and to determine its location in the genome. The PCR strategy used primers designed from conserved regions at the end of the atpG gene (γ) and beginning of the atpD gene (β). PCR products with the expected sizes were cloned and sequenced.

Apmis, Nov 18, 2016

The asymptomatic nature of most Chlamydia trachomatis infections and the lack of appropriate effe... more The asymptomatic nature of most Chlamydia trachomatis infections and the lack of appropriate effects by current prevention and management call for vaccine development. We evaluated a recombinant subunit vaccine candidate based on the major outer membrane protein variable segments 2 and 4 (MOMP VS2/4). To achieve maximal immunogenicity and ease of production and purification, MOMP VS2/4 was constructed by using highly immunogenic sequences of MOMP only, thereby minimizing the presence of hydrophobic regions, and spacing the immunogenic epitopes with a flexible amino acid sequence. A purification tag was also added. The MOMP VS2/4 was given intranasally, with or without intravaginal boost, with cholera toxin (CT) adjuvant to C57BL/6 mice, which were screened for immunogenicity and protection against a live challenge infection with C. trachomatis serovar D. Bacterial shedding, cell-mediated responses, and antibody responses were monitored. Immunized mice exhibited significantly less bacterial shedding and were better protected against infertility as compared to unimmunized control mice. Immunizations stimulated both systemic and local specific antibody (IgG1, IgG2c, and IgA) responses, and primed T cells that produced interferon-γ and interleukins 13 and 17 upon challenge with recall antigen. Thus, MOMP VS2/4, in combination with CT adjuvant, stimulated Th1, Th2, and Th17 effector cells, and generated protective immunity associated with less pathology. We regard MOMP VS2/4 as a promising candidate for further development into a mucosal chlamydial vaccine.

Journal of Chemical Information and Modeling, May 24, 2011

A homology model of the Arabidopsis thaliana UV resistance locus 8 (UVR8) protein is presented he... more A homology model of the Arabidopsis thaliana UV resistance locus 8 (UVR8) protein is presented herein, showing a seven-bladed β-propeller conformation similar to the globular structure of RCC1. The UVR8 amino acid sequence contains a very high amount of conserved tryptophans, and the homology model shows that seven of these tryptophans cluster at the 'top surface' of the UVR8 protein where they are intermixed with positive residues (mainly arginines) and a couple of tyrosines. Quantum chemical calculations of excitation spectra of both a large cluster model involving all twelve above-mentioned residues and smaller fragments thereof reveal that absorption maxima appearing in the 280-300 nm range for the full cluster result from interactions between the central tryptophans and surrounding arginines. This observation coincides with the published experimentally measured action spectrum for the UVR8-dependent UV-B stimulation of HY5 transcription in mature A. thaliana leaf tissue. In total these findings suggest that UVR8 has in fact in itself the ability to be an ultraviolet-B photoreceptor in plants.

Journal of Physical Chemistry B, Jun 26, 2009

Molecules acting as antioxidants capable of scavenging reactive oxygen species (ROS) are of the u... more Molecules acting as antioxidants capable of scavenging reactive oxygen species (ROS) are of the utmost importance in the living cell. The antioxidative properties of pyridoxine (vitamin B 6) have recently been discovered. Previous theoretical calculations have shown a high reactivity of pyridoxine toward hydroxyl radicals, where the latter preferably abstract H from either carbon of the two methanol substituents (C8 or C9). In this study, we have explored the reactivity of pyridoxine toward further hydroxyl radicals, considering as the first step the H abstraction from either C8 or C9, also including addition reactions and cyclization. Many of the reactions display similar ∆G, and hence, the quenching of hydroxyl radicals by pyridoxine may undergo different pathways leading to a mix of products. In addition, we observe that pyridoxine, under high hydroxyl radical concentrations, may scavenge up to eight radicals, supporting its observed high antioxidant activity.

Plant and Cell Physiology, Oct 1, 1992

Frontiers in Plant Science, Jan 5, 2021

Ultraviolet B (UV-B) (280-315 nm) and ultraviolet A (UV-A) (315-400 nm) radiation comprise small ... more Ultraviolet B (UV-B) (280-315 nm) and ultraviolet A (UV-A) (315-400 nm) radiation comprise small portions of the solar radiation but regulate many aspects of plant development, physiology and metabolism. Until now, how plants respond to UV-B in the presence of different light qualities is poorly understood. This study aimed to assess the effects of a low UV-B dose (0.912 ± 0.074 kJ m −2 day −1 , at a 6 h daily UV exposure) in combination with four light treatments (blue, green, red and broadband white at 210 µmol m −2 s −1 Photosynthetically active radiation [PAR]) on morphological and physiological responses of cucumber (Cucumis sativus cv. "Lausanna RZ F1"). We explored the effects of light quality backgrounds on plant morphology, leaf gas exchange, chlorophyll fluorescence, epidermal pigment accumulation, and on acclimation ability to saturating light intensity. Our results showed that supplementary UV-B significantly decreased biomass accumulation in the presence of broad band white, blue and green light, but not under red light. UV-B also reduced the photosynthetic efficiency of CO 2 fixation (α) when combined with blue light. These plants, despite showing high accumulation of anthocyanins, were unable to cope with saturating light conditions. No significant effects of UV-B in combination with green light were observed for gas exchange and chlorophyll fluorescence parameters, but supplementary UV-B significantly increased chlorophyll and flavonol contents in the leaf epidermis. Plants grown under red light and UV-B significantly increased maximum photosynthetic rate and dark respiration compared to pure red light. Additionally, red and UV-B treated plants exposed to saturating light intensity showed higher quantum yield of photosystem II (PSII), fraction of open PSII centres and electron transport rate and showed no effect on the apparent maximum quantum efficiency of PSII photochemistry (F v /F m) or non-photochemical quenching, in contrast to solely red-light conditions. These findings provide new insights into how plants respond to UV-B radiation in the presence of different light spectra.

Physiologia Plantarum, Sep 23, 2021

During recent years, we have advanced our understanding of plant molecular responses to ultraviol... more During recent years, we have advanced our understanding of plant molecular responses to ultraviolet radiation (UV, 280–400 nm); however, how plants respond to UV radiation under different spectral light qualities is poorly understood. In this study, cucumber plants (Cucumis sativus “Lausanna RZ F1”) were grown under monochromatic blue, green, red, and broadband white light in combination with UV radiation. The effects of light quality and UV radiation on acclimatory responses were assessed by measuring transcript accumulation of ELONGATED HYPOCOTYL 5 (HY5), CHALCONE SYNTHASE 2 (CHS2), and LIGHT HARVESTING COMPLEX II (LHCII), and the accumulation of flavonoids and hydroxycinnamic acids in the leaves. The growth light backgrounds differentially regulated gene expression and metabolite accumulation. While HY5 and CHS2 transcripts were induced by blue and white light, LHCII was induced by white and red light. Furthermore, UV radiation antagonized the effects of blue, red, green, and white light on transcript accumulation in a gene‐dependent manner. Plants grown under blue light with supplementary UV radiation increased phenylalanine, flavonol disaccharide I and caffeic acid contents compared to those exposed only to blue light. UV radiation also induced the accumulation of flavonol disaccharide I and II, ferulic acid hexose and coumaric acid hexose in plants grown under green light. Our findings provide a further understanding of plant responses to UV radiation in combination with different light spectra and contribute to the design of light recipes for horticultural practices that aim to modify plant metabolism and ultimately improve crop quality.

Plant Physiology, Oct 1, 1999

A pea (Pisum sativum) DNA fragment (termed MB3) was isolated by differential display of cDNAs obt... more A pea (Pisum sativum) DNA fragment (termed MB3) was isolated by differential display of cDNAs obtained from total leaf RNA of ultraviolet B (UV-B) radiation-treated plants. Longer cDNAs were cloned by rapid amplification of cDNA ends in the 3 to 5 direction. Three different, but very similar, cDNAs were cloned, sadA, sadB, and sadC, the major difference between them being a 36-bp deletion in the coding region of sadB. Southern blotting confirmed the occurrence of at least three genes in the pea genome. Database comparisons of the SAD protein sequences revealed high identity (46%) and similarity (77%) with a putative tomato (Lycopersicon esculentum) short-chain alcohol dehydrogenase. Very low levels of UV-B radiation (the biologically effective radiation normalized to 300 nm ‫؍‬ 0.08 W m ؊2) was shown to up-regulate expression, a dose considerably lower than that needed to induce expression of the well-known UV-B defensive chalcone synthase and phenylalanine ammonia lyase genes. RNase protection assay revealed that primarily sadA and sadC mRNA accumulation was enhanced by UV-B. In addition to UV-B irradiation, ozone fumigation, wounding, aluminum stress, and salt stress induced increased transcript levels of the sad genes in pea.

Vaccines, Oct 6, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Photochemical & Photobiological Sciences

SSRN Electronic Journal, 2022

The F-type ATP synthase supplies the cell with ATP using the energy from proton gradients across ... more The F-type ATP synthase supplies the cell with ATP using the energy from proton gradients across membranes to phosphorylate ADP. The F1 catalytic subunit consists of five subunits: α, β, γ, δ and e. The genes encoding these subunits in bacteria are clustered in one operon, called the atp operon. The conserved gene order in the atp operons of chloroplasts, Escherichia coli, Rhodospirillum rubrum, Rhodobacter blasticus and some cyanobacteria, indicates common ancestry [1]. An interesting feature of the Rb. blasticus atp operon is that a sixth gene, termed URF6, is placed between the genes for the γ and β subunits [2]. Since the genes of the atp operon are co-transcribed, the URF6 gene product may be involved in the ATP synthase. Previously, we have raised antibodies towards the URF6 gene product, and used them to investigate the presence of this protein in several other bacteria and during purification of the overexpressed recombinant protein [3]. Our studies indicate that Paracoccus ...

In greenhouses, crops are protected from adverse weather conditions allowing year-round productio... more In greenhouses, crops are protected from adverse weather conditions allowing year-round production. However, this comes with a trade-off, which is the lack of UV-A and UV-B exposure. Excess of UV impairs plant growth and nutrient absorption, while lack of UV in greenhouses reduce the synthesis of metabolites associated with nutritional and sensorial quality of plants. Here, we provide insights into how the application of sensomics, an approach that combines top-down system biology approaches, such as metabolomics, with sensory science, can help to bridge the gap between plant science and horticultural quality.

We previously showed that UV-B can increase metabolic hydrogen peroxide (H2O2)concentrations in l... more We previously showed that UV-B can increase metabolic hydrogen peroxide (H2O2)concentrations in leaves and that it is able to convert H2O2 to hydroxyl radicals (•OH) (Czegeny et al. 2014). Thus, efficient scavenging of H2O2 and •OH are expected to be important aspects in a successful acclimation to UV-B. Vitamin B6 has an essential role both in plant development and stress tolerance (Raschke et al. 2011). In addition to their coenzyme function in several biosynthetic pathways (Drewke and Leistner 2001), B6 derivates are potent quenchers of ROS(Havaux et al. 2009, Matxain et al. 2009). In this study, we used Arabidopsis thaliana mutants (rsr4-1) reduced in B6 biosynthesis (Wagner et al. 2006) to investigate how vitamin B6 derivates of contribute to the plants’ acclimation to supplemental UV-B in growth chambers. In response to UV-B both mutant and wild type (C24) leaves altered their antioxidant profiles – including increases in B6 derivates. Wild type plants avoided oxidative stress...