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1.	Landberg, Tommy, et al. (författare) No phytochelatin (PC2 and PC3) detected in Salix viminalis 2004 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 121:3, s. 481-487 Tidskriftsartikel (refereegranskat)abstract Phytochelatins (PCs) have been detected in a large range of plant species, but their role in heavy-metal tolerance is unclear. Various clones of Salix viminalis are differently tolerant to heavy metals, and the aim of this work was to investigate whether PCs were differently expressed in tolerant compared with sensitive clones. In a long-term study, five clones with high or low metal tolerance were cultivated 21 days without or with Cd (1 or 10 µM), Cu (0.3 or 7 µM), Ni (15 µM), Pb (7 µM) or Zn (10 or 100 µM). Controls were further used in a short-term study where Cd (1 µM) was added and samples were collected 0, 15 and 30 min, 1, 3 and 24 h after start of treatment. PCs were analysed on high performance liquid chromatography (HPLC) using two different methods: post-column derivatization using Ellmans reagent and pre-derivatization with monobromobimane. Thlaspi caerulescens treated with Cd was used as internal PC standard. No PCs could be detected in Salix with either of the two methods in any of the treatments: different clones, metals, concentrations, plant parts or treatment time. The 16 thiol peaks shown were the same in both control and treated plants. Both HPLC methods showed PC peaks when Thlaspi was used but these peaks could not be associated with any of the 16 peaks. The amino acid composition of the 16 peaks was not the expected composition of that of PCs. Thus, Salix viminalis have no detectable levels of PCs, which in turn are not involved in heavy metal tolerance in Salix
2.	Noren, H, et al. (författare) A convenient and versatile hydroponic cultivation system for Arabidopsis thaliana 2004 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 121:3, s. 343-348 Tidskriftsartikel (refereegranskat)abstract A versatile two-step cultivation procedure for Arabidopsis thaliana is described for the production of large quantities of leaf material suitable for biochemical and biophysical analysis. The first step comprises a miniature greenhouse made out of a plastic pipette box to grow the seedlings to the six-leaf stage. For continued growth, the seedlings are transferred to hydroponic cultivation using an opaque container covered by a styrofoam lid. Transfer of the small seedlings to hydroponic culture is facilitated by growth in separate pipette tips, which protects vulnerable roots from damage. The hydroponic cultivation system is easy to scale-up and produces large amounts of relatively large leaves and roots. This hydroponic system produces enough plant material to make Arabidopsis a feasible model for biochemical and biophysical experiments, which can be combined with the available genetic information to address various aspects of plant functional genomics
3.	Solymosi, K., et al. (författare) Plastid differentiation and chlorophyll biosynthesis in different leaf layers of white cabbage (Brassica oleracea cv. capitata) 2004 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 121:3, s. 520-529 Tidskriftsartikel (refereegranskat)abstract The contents of protochlorophyllide, protochlorophyll and chlorophyll together with the native arrangements of the pigments and the plastid ultrastructure were studied in different leaf layers of white cabbage (Brassica oleracea cv. capitata) using absorption, 77 K fluorescence spectroscopy and transmission electron microscopy. The developmental stage of the leaves was determined using the differentiation of the stoma complexes as seen by scanning electron microscopy and light microscopy. The pigment content showed a gradual decrease from the outer leaf layer towards the central leaves. The innermost leaves were in a primordial stage in many aspects; they were large but had typical proplastids with few simple inner membranes, and contained protochlorophyllide and its esters in a 2 : 1 ratio and no chlorophyll. Short-wavelength, not flash-photoactive protochlorophyllide and/or protochlorophyll forms emitting at 629 and 636 nm were dominant in the innermost leaves. These leaves also had small amounts of the 644 and 654 nm emitting, flash-photoactive protochlorophyllide forms. Rarely prolamellar bodies were observed in this layer. The outermost leaves had the usual characteristics of fully developed green leaves. The intermediary layers contained chlorophyll a and chlorophyll b besides the protochlorophyll(ide) pigments and had various intermediary developmental stages. Spectroscopically two types of intermediary leaves could be distinguished: one with only a 680 nm emitting chlorophyll a form and a second with bands at 685, 695 and 730 nm, corresponding to chlorophyll-protein complexes of green leaves. In these leaves, a large variety of chloroplasts were found. The data of this work show that etioplasts, etio-chloroplasts or chloro-etioplasts as well as etiolated leaves do exist in the nature and not only under laboratory conditions. The specificity of cabbage leaves compared with those of dark-grown seedlings is the retained primordial or intermediary developmental stage of leaves in the inner layers for very long (even for a few month) period. This opens new developmental routes leading to formation of specially developed plastids in the various cabbage leaf layers. The study of these plastids provided new information for a better understanding of the plastid differentiation and the greening process.
4.	Abdelkader, Amal F., 1969, et al. (författare) High salt stress in wheat leaves causes retardation of chlorophyll accumulation due to a limited rate of protochlorophyllide formation 2007 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 130:1, s. 157-166 Tidskriftsartikel (refereegranskat)abstract When exposed to salt stress, leaves from dark-grown wheat seedlings (Triticum aestivum, cv. Giza 168) showed reduced accumulation of chlorophyll during irradiation. To elucidate the mechanism behind salt-influenced reduction of chlorophyll biosynthesis, we have investigated the effect of salt stress on the spectral forms of Pchlide, the phototransformation of Pchlide to Chlide, the Shibata shift, the regeneration of Pchlide and the accumulation of Pchlide from 5-aminolevulinic acid (ALA). We found that the phototransformation of Pchlide to Chlide was not affected by salt stress. The blue shift (Shibata shift) of newly formed Chlide was delayed both after flash irradiation and in continuous light. The reformation of Pchlide in darkness after a flash irradiation or after a period of 3-h irradiation was retarded in the salt-treated leaves. However, after a 20-h dark period, Pchlide was reformed even in salt-treated leaves but the formation of short-wavelength Pchlide was suppressed. Compared to controls, salt treatment also reduced the amount of Pchlide accumulated in leaves floated on ALA. The increase in the low temperature fluorescence emission spectrum at 735 nm, which occurred gradually during several hours of irradiation with continuous light in control leaves, was completely suppressed in salt-treated leaves. It is concluded that salt stress inhibits chlorophyll accumulation partly by reducing the rate of porphyrin formation but, as discussed, also by a possible reduction in the formation of chlorophyll-binding proteins.
5.	Agius, Stephanie C, et al. (författare) The internal rotenone-insensitive NADPH dehydrogenase contributes to malate oxidation by potato tuber and pea leaf mitochondria 1998 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 104:3, s. 329-336 Tidskriftsartikel (refereegranskat)abstract Inside-out submitochondrial particles from both potato (Solanum tuberosum L. cv. Bintje) tubers and pea (Pisum sativum L. cv. Oregon) leaves possess three distinct dehydrogenase activities: Complex I catalyzes the rotenone-sensitive oxidation of deamino-NADH, NDin(NADPH) catalyzes the rotenone-insensitive and Ca2+-dependent oxidation of NADPH and NDin(NADH) catalyzes the rotenone-insensitive and Ca2+-independent oxidation of NADH. Diphenylene iodonium (DPI) inhibits complex I, NDin(NADPH) and NDin (NADH) activity with a Ki of 3.7, 0.17 and 63 µM, respectively, and the 400-fold difference in Ki between the two NDin made possible the use of DPI inhibition to estimate NDin (NADPH) contribution to malate oxidation by intact mitochondria. The oxidation of malate in the presence of rotenone by intact mitochondria from both species was inhibited by 5 µM DPI. The maximum decrease in rate was 10–20 nmol O2 mg-1 min-1. The reduction level of NAD(P) was manipulated by measuring malate oxidation in state 3 at pH 7.2 and 6.8 and in the presence and absence of an oxaloacetate-removing system. The inhibition by DPI was largest under conditions of high NAD(P) reduction. Control experiments showed that 125 µM DPI had no effect on the activities of malate dehydrogenase (with NADH or NADPH) or malic enzyme (with NAD+ or NADP+) in a matrix extract from either species. Malate dehydrogenase was unable to use NADP+ in the forward reaction. DPI at 125 µM did not have any effect on succinate oxidation by intact mitochondria of either species. We conclude that the inhibition caused by DPI in the presence of rotenone in plant mitochondria oxidizing malate is due to inhibition of NDin(NADPH) oxidizing NADPH. Thus, NADP turnover contributes to malate oxidation by plant mitochondria.
6.	Albertsson, Per-Åke, et al. (författare) The constant proportion of grana and stroma lamellae in plant chloroplasts 2004 Ingår i: Physiologia Plantarum. - 0031-9317. ; 121:2, s. 334-342 Tidskriftsartikel (refereegranskat)abstract The relative proportion of stroma lamellae and grana end membranes was determined from electron micrographs of 58 chloroplasts from 21 different plant species. The percentage of grana end membranes varied between 1 and 21% of the total thylakoid membrane indicating a large variation in the size of grana stacks. By contrast the stroma lamellae account for 20.3 +/- 2.5 (SD)% of the total thylakoid membrane. A plot of percentage stroma lamellae against percentage of grana end membranes fits a straight line with a slope of zero showing that the proportion of stroma lamellae is independent of the size of the grana stacks. That stroma lamellae account for about 20% of the thylakoid membrane is in agreement with fragmentation and separation analysis (Gadjieva et al. Biochim. Biophys. Acta 144: 92-100, 1999). Chloroplasts from spinach, grown under high or low light, were fragmented by sonication and separated by countercurrent distribution into two vesicle populations originating from grana and stroma lamellae plus end membranes, respectively. The separation diagrams were very similar lending independent support for the notion that the proportion of stroma lamellae is constant. The results are discussed in relation to the composition and function of the chloroplast in plants grown under different environmental conditions, and in relation to a recent quantitative model for the thylakoid (Albertsson, Trends Plant Sci. 6: 349-354, 2001).
7.	Allahverdiyeva, Yagut, et al. (författare) NordAqua, a Nordic Center of Excellence to develop an algae-based photosynthetic production platform 2021 Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 173:2, s. 507-513 Tidskriftsartikel (refereegranskat)abstract NordAqua is a multidisciplinary Nordic Center of Excellence funded by NordForsk Bioeconomy program (2017–2022). The research center promotes Blue Bioeconomy and endeavours to reform the use of natural resources in a environmentally sustainable way. In this short communication, we summarize particular outcomes of the consortium. The key research progress of NordAqua includes (1) improving of photosynthetisis, (2) developing novel photosynthetic cell factories that function in a “solar-driven direct CO2 capture to target bioproducts” mode, (3) promoting the diversity of Nordic cyanobacteria and algae as an abundant and resilient alternative for less sustainable forest biomass and for innovative production of biochemicals, and (4) improving the bio-based wastewater purification and nutrient recycling technologies to provide new tools for integrative circular economy platforms.
8.	Amirjani, M. R., et al. (författare) Protochlorophyllide and POR development in dark-grown plants with different proportions of short-wave length and long-wavelength protochlorophyllide spectral forms 2006 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 128:4, s. 751-762 Tidskriftsartikel (refereegranskat)abstract The effect of leaf developmental age on the protochlorophyllide (Pchlide) spectral forms and the expression of messenger RNA (mRNA) encoding NADPH-protochlorophyllide oxidoreductase (POR) were investigated. Four plant species, maize, wheat, pea and the lip 1 mutant of pea, known to have different composition of the spectral forms of Pchlide, were used. In very young plants short-wavelength Pchlide with a fluorescence emission at 631 nm was dominating. Long-wavelength Pchlide fluorescing mainly around 655 nm increased during development, which led to a relative decrease of the short-wavelength forms. During ageing of the leaves, the short-wavelength forms slightly increased again. The different proportions of short- and long-wavelength Pchlide spectral forms were, however, found to vary with the developmental stage in a species specific pattern. The steady-state level of POR mRNA and the amount of the POR protein were similar in species dominated by short-wavelength forms and in species dominated with long-wavelength forms. Even if POR is necessary for the formation of the long-wavelength Pchlide form it is not the only limiting factor for formation of long-wavelength Pchlide forms in mature plants.
9.	Amirjani, M. R., et al. (författare) Regeneration of protochlorophyllide in green and greening leaves of plants with varying proportions of protochlorophyllide forms in darkness 2004 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 121:3, s. 377-390 Tidskriftsartikel (refereegranskat)abstract During illumination of dark-grown plants protochlorophyllide (Pchlide) is continuously transformed to chlorophyllide (Chlide). Different dark-grown plants, maize (Zea mays cv. Sundance), wheat (Triticum aestivum cv. Kosack), pea (Pisum sativum cv. Kelwedon wonder), the lip1 mutant of pea, and the aurea mutant of tomato (Solanum lycopersicum), have various ratios of spectral Pchlide forms in darkness. When the plants were illuminated and then returned to darkness Pchlide re-accumulated. The proportions of different Pchlide forms within the pool of re-accumulated Pchlide were followed by low temperature fluorescence emission and excitation spectra in green and greening leaves. After 1 h of illumination the spectral characteristics of regenerated Pchlide forms mirrored those of Pchlide in dark-grown plants and were thus species dependent. After a prolonged illumination period (24 h) as well as in fully green leaves energy transfer to chlorophyll (Chl) masked the presence of long-wavelength Pchlide in the fluorescence emission spectra. However, excitation spectra showed Pchlide absorption around 650 nm and its flash-induced disappearance confirmed its nature of phototransformable Pchlide. In fact the excitation spectra showed that the proportions of different Pchlide forms in green leaves highly resembled the proportions of Pchlide forms in dark-grown leaves and were specific for the plant variety. Thus Chl formation in both dark-grown and light-grown leaves can occur in a similar way through the main photoactive long-wavelength form of Pchlide.
10.	Andersson, Mariette, et al. (författare) Genome editing in potato via CRISPR-Cas9 ribonucleoprotein delivery 2018 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 164, s. 378-384 Tidskriftsartikel (refereegranskat)abstract Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein-9 (CRISPR-Cas9) can be used as an efficient tool for genome editing in potato (Solanum tuberosum). From both a scientific and a regulatory perspective, it is beneficial if integration of DNA in the potato genome is avoided. We have implemented a DNA-free genome editing method, using delivery of CRISPR-Cas9 ribonucleoproteins (RNPs) to potato protoplasts, by targeting the gene encoding a granule bound starch synthase (GBSS, EC 2.4.1.242). The RNP method was directly implemented using previously developed protoplast isolation, transfection and regeneration protocols without further adjustments. Cas9 protein was preassembled with RNA produced either synthetically or by in vitro transcription. RNP with synthetically produced RNA (cr-RNP) induced mutations, i.e. indels, at a frequency of up to 9%, with all mutated lines being transgene-free. A mutagenesis frequency of 25% of all regenerated shoots was found when using RNP with in vitro transcriptionally produced RNA (IVT-RNP). However, more than 80% of the shoots with confirmed mutations had unintended inserts in the cut site, which was in the same range as when using DNA delivery. The inserts originated both from DNA template remnants from the in vitro transcription, and from chromosomal potato DNA. In 2-3% of the regenerated shoots from the RNP-experiments, mutations were induced in all four alleles resulting in a complete knockout of the GBSS enzyme function.
11.	Annacondia López, María Luz, et al. (författare) Stress response regulation by epigenetic mechanisms: changing of the guards 2018 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 162, s. 239-250 Tidskriftsartikel (refereegranskat)abstract Plants are sessile organisms that lack a specialized immune system to cope with biotic and abiotic stress. Instead, plants have complex regulatory networks that determine the appropriate distribution of resources between the developmental and the defense programs. In the last years, epigenetic regulation of repeats and gene expression has evolved as an important player in the transcriptional regulation of stress-related genes. Here, we review the current knowledge about how different stresses interact with different levels of epigenetic control of the genome. Moreover, we analyze the different examples of transgenerational epigenetic inheritance and connect them with the known features of genome epigenetic regulation. Although yet to be explored, the interplay between epigenetics and stress resistance seems to be a relevant and dynamic player of the interaction of plants with their environments.
12.	Aronsson, Henrik, et al. (författare) Characterisation of the assembly pathway of the pea NADPH:protochlorophyllide (Pchlide) oxidoreductase (POR), with emphasis on the role of its substrate, Pchlide 2001 Ingår i: Physiologia Plantarum. - Hoboken, NJ : Wiley-Blackwell Publishing Inc.. - 0031-9317 .- 1399-3054. ; 111:2, s. 239-244 Tidskriftsartikel (refereegranskat)abstract The homologous import and membrane association of a key enzyme for chlorophyll biosynthesis, the NADPH:protochlorophyllide (Pchlide) oxidoreductase (PAR, EC 1.6.99.1) into pea chloroplasts was investigated in vitro. The co-factor, NADPH, decreased binding of the precursor protein (pPOR) to the envelope membranes in the presence of ATP. The decrease of the binding reaction with NADPH was not observed with the precursor of the small subunit of Rubisco (pSS). To investigate possible substrate-dependency for the import reaction, internal Pchlide concentrations in the plastids were raised by either an addition of ÎŽ-aminolevulinic acid to isolated plastids or etiolation of the seedlings prior to plastid isolation. Increased amounts of plastid-bound Pchlide gave no observable differences in POR import. The capacity of POR and 11 different POR mutants, carrying charged-to-alanine scanning substitutions, to form a catalytically active POR-Pchlide-NADPH complex and to associate with the thylakoid membranes in a protease-resistant way were tested. Wild-type POR, as well as the mutants with charge substitutions in the N-terminal region of the protein, exhibited higher catalytic activity than the POR mutants carrying substitutions in the C-terminal region. Formation of a catalytically active complex did not, however, increase the association efficiency onto the thylakoids. We can, therefore, postulate that the import of pea POR into pea chloroplasts was not substrate-dependent, nor did formation of catalytically active complexes stimulate or inhibit the membrane association reaction of POR.
13.	Aronsson, Henrik, et al. (författare) POR – import and membrane association of a key element in chloroplast development 2003 Ingår i: Physiologia Plantarum. - : Blackwell Publishing. - 0031-9317 .- 1399-3054. ; 118:1, s. 1-9 Tidskriftsartikel (refereegranskat)abstract The development of proplastids or etioplasts to chloroplast is visualized by the accumulation of chlorophyll in leaves of higher plants. The biosynthesis of chlorophyll includes a light-dependent reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide). This light-dependent step is catalysed by the nucleus-encoded NADPH:Pchlide oxidoreductase (POR, EC 1.6.99.1). POR is active within plastids and therefore has to be translocated over the plastid envelope membranes. The import of chloroplast proteins seems to follow a general import pathway using translocons at the outer and inner envelope membrane. POR cross-linking to Toc75, one of the major translocon components at the outer envelope membrane, indicates its use of the general import pathway. However, since variations exist within the so-called general import pathway one has to consider previous data suggesting a novel totally Pchlide-dependent import pathway of one POR isoform, PORA. The suggested Pchlide dependency of POR import is discussed since recent observations contradict this idea. In the stroma the POR transit peptide is cleaved off and the mature POR protein is targeted to the plastid inner membranes. The correct and stable association of POR to the membrane requires the cofactor NADPH. Functional activity of POR calls for formation of an NADPH–Pchlide–POR complex, a formation that probably takes place after the membrane association and is dependent on a phosphorylation reaction.
14.	Askerlund, Per, et al. (författare) Cytochromes of plant plasma membranes : Characterization by absorbance difference spectrophotometry and redox titration 1989 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 76:2, s. 123-134 Tidskriftsartikel (refereegranskat)abstract The cytochrome composition of plasma membranes (PM) obtained by phase partitioning of microsomal fractions from spinach leaves (Spinacea oleracea L. cv. Medania), cauliflower inflorescences (Brassica oleracea L.), sugar beer leaves (Beta vulgaris L.) and barley (Hordeum vulgare L. cv. Kristina) roots and leaves was characterized by absorbance difference spectrophotometry at different reducing conditions at 20 and – 196°C, by redox titration, and by heme staining of polypeptide bands after lithium dodecyl sulfate polyacrylamide gel electrophoresis (LDS-PAGE). The location of the α-bands in the difference spectra and the loss of heme after treatment with LDS indicated that predominantly cytochromes of the b-type were present in all species tested. The total concentration of cytochrome was ca 0.35 nmol (mg protein)−1. The main component (ca 70% of total) was completely reduced by ascorbate and partly by NADH and had a midpoint potential of ca 150 mV. At – 196°C, ascorbate reduction revealed a symmetrical α-band at ca 557 nm with PM from spinach leaves, cauliflower and sugar beet leaves, but with barley root and leaf PM ascorbate reduction resulted in an asymmetrical α-band (shoulder at 552, maximum at 559 nm). In the dithionite-reduced minus ascorbate-reduced spectrum at –196°C a split α-band (552 + 558 nm) was seen with PM from all species. This minor component had a midpoint potential of ca – 50 mV and is probably identical to cytochrome b5, the presence of which would explain the relatively high NADH-cytochrome c reductase activities observed with plant PM. With PM from cauliflower, CO-difference spectra indicated that cytochromes P-420 and P-450 were present at concentrations up to 0.06 and 0.03 nmol (mg protein)−1, respectively. Visualization of cytochromes by heme staining after LDS-PAGE was complicated by endogenous peroxidase activity and by loss of heme during solubilisation. A presumptive b-cytochrome (heme-stained band at 94 kDa) was only detected with barley leaf PM.
15.	Askerlund, Per, et al. (författare) NAD(P)H oxidase and peroxidase activities in purified plasma membranes from cauliflower inflorescences. 1987 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 71:1, s. 9-19 Tidskriftsartikel (refereegranskat)
16.	Baral, Anirban (författare) Bananas tackling drought and heat - with DREBs and more 2019 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 165, s. 128-130 Tidskriftsartikel (refereegranskat)abstract With the changing climate, crops are facing mounting threats from multiple abiotic stresses, and studies that assess the response of plants to combinations, rather than to individual, abiotic stresses are becoming increasingly relevant. Bananas are one of the most globally important and popular food crops and their production is threatened by increasing heat and diminishing rainfall in tropical and subtropical regions. In pursuit of effective stress management strategies, Jangale et al. (2019) look into the physiological and molecular responses of banana plants to combined heat and drought stresses.
17.	Baral, Anirban (författare) Finding the fragrance genes of wintersweet 2019 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 166, s. 475-477 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Fragrant flowers emit a complex mixture of volatile organic compounds (VOCs) that we perceive as pleasant. While we know the chemical nature of these volatiles, the molecular traits that regulate their biosynthesis are poorly understood. In this issue, Tian et al. (2019) compare the transcriptomic and proteomic profiles of a scented genotype of wintersweet (Chimonanthus praecox) with a non-scented one. By correlating the differential gene expression profile with the observed differences in VOC profiles, they attempt to identify the genes that regulate the fragrance of wintersweet.
18.	Baral, Anirban (författare) Lazy rice in space: gravity regulates helical movement in plants 2019 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 165, s. 448-450 Tidskriftsartikel (refereegranskat)abstract Circumnutation, the helical movement of organs, has been observed in diverse species of land plants. Whether circumnutation arises purely from internal growth oscillations or as a response to exogenous forces such as gravity is a subject of active debate. By observing rice seedlings grown under microgravity at the International Space Station (ISS) and analyzing the agravitropic lazy1 mutant, Kobayashi et al. (2019) propose gravity as the causal force that regulates circumnutation of rice coleoptiles.
19.	Baral, Anirban (författare) Parasitic worms hijack key plant protein to build their nest 2019 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 165, s. 2-3 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Parasitic nematode worms infect a variety of crop plants worldwide. Roots infected by these worms start to look rather unsavory-with knot like tumors (galls) developing all over them. At the core of each gall, a worm matures and lays its eggs. Olmo et al. (2018) looked into the developmental reprogramming that leads to gall formation and found an Arabidopsis protein to be a necessary component in this process.
20.	Baral, Anirban (författare) Strawberries under salt stress: ALA and ROS to the rescue 2019 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 167, s. 2-4 Tidskriftsartikel (refereegranskat)abstract Generating salt-tolerant plants that can cope with increasing soil salinity is a major goal of crop-breeding programs worldwide. Together with genetic approaches, research efforts are focusing on finding chemical modulators of salt tolerance. The exogenous application of 5-aminolevulinic acid (ALA) has been shown to improve salt tolerance in diverse crop species, but its mechanism of action is not properly understood. Wu et al. (2019) report that ALA treatment enhances reactive oxygen species (ROS) production in the roots of salt-stressed strawberry plants. Activation of several key ion transporters downstream to the ROS signal helps to sequester the toxic Na+ ions in the roots and protects the shoots against salt stress.
21.	Bennett, Malcolm (författare) Integrative biology : dissecting cross-talk between plant signalling pathways 2005 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 123:2, s. 109-109 Forskningsöversikt (övrigt vetenskapligt/konstnärligt)
22.	Bennett, M, et al. (författare) Integrative biology: dissecting cross talk between plant signaling pathways 2005 Ingår i: Physiologia Plantarum. - 0031-9317 .- 1399-3054. ; 123, s. 109- Forskningsöversikt (populärvet., debatt m.m.)
23.	Berckx, Fede (författare) In the Spotlight: Getting to the roots of fungal interactions 2024 Ingår i: Physiologia Plantarum. - 0031-9317 .- 1399-3054. ; 176 Tidskriftsartikel (refereegranskat)
24.	Bhalerao, RP, et al. (författare) Factors influencing the phycobilisome rod composition of the cyanobacterium synechococcus sp pcc-7942 : effects of reduced phycocyanin content, lack of rod-linkers, and over-expression of the rod-terminating linker 1994 Ingår i: Physiologia Plantarum. - 0031-9317 .- 1399-3054. ; 90:1, s. 187-197 Tidskriftsartikel (refereegranskat)abstract Four novel mutants with altered phycobilisomes were constructed in the cyanobacterium Synechococcus 7942 to study factors influencing the rod length and composition. These mutants show (1) reduced phycocyanin content, (2) reduced phycocyanin content combined with loss of the 33 kDa linker, (3) loss of the 30 kDa rod-linker and (4) overexpression of the 9 kDa rod terminating linker. For these mutants we determined the 33 to 27 kDa and 30 to 27 kDa linker ratios in the isolated phycobilisomes and compared these ratios with those in the wild type. The 30 kDa linker can be incorporated into the rods in absence of the 33 kDa linker. The incorporation of the 30 kDa linker is lower in absence of the 33 kDa linker. When the 30 kDa linker is missing, an increase in the level of the 33 kDa linker is seen, indicating that there could be an excess of the 33 kDa linker in the cells. Our results also show that a reduction in the phycocyanin content causes a decrease in the rod length simultaneously with a reduction of the 30/27 linker ratio, without altering the 33/27 ratio. Reduced phycocyanin content and absence of the 33 kDa linker cause a dramatic reduction in the incorporation of the 30 kDa linker into the rods in the mutant B2SMIKM. Over-expression of the 9 kDa linker results in a decreased incorporation of both the 33 and 30 kDa linkers into the rods, the effect being more pronounced for the 30 kDa linker. This result indicates that the level of the 9 kDa linker relative to those of the 33 and the 30 kDa linkers may be an important determinant of the phycobilisome rod length.
25.	Bhalerao, Rishikesh P., et al. (författare) Auxin gradients across wood – instructive or incidental? 2014 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 151, s. 43-51 Forskningsöversikt (refereegranskat)abstract Various aspects of wood formation have been linked to the action of auxin, e.g. cambial activity, dormancy, secondary cell wall deposition and tension wood formation. The presence of a radial auxin concentration gradient across wood-forming tissue has been suggested to regulate cambial activity and differentiation of cambial derivatives by providing positional information to cells within the tissue. Similar patterning mechanisms that depend on the interpretation of auxin thresholds have subsequently been proposed for shoot and root apical meristems. However, direct evidence for the existence of auxin gradients has only been obtained for the cambium of various tree species. While the auxin gradient theory is based on a plethora of descriptive and pharmacological experiments, in recent years, auxin function on wood formation has been underpinned by molecular and functional data. Here, we review the latest progress in understanding the role of auxin in wood formation and discuss how auxin concentration gradients could be established and interpreted in wood-forming tissues.
26.	Bishop, NI, et al. (författare) CORRELATION OF THE PHOTOSYSTEM-I AND PHOTOSYSTEM-II REACTION CENTER CHLOROPHYLL-PROTEIN COMPLEXES, CP-AI AND CP-AII, WITH PHOTOSYSTEM ACTIVITY AND LOW-TEMPERATURE FLUORESCENCE EMISSION PROPERTIES IN MUTANTS OF SCENEDESMUS 1980 Ingår i: Physiologia Plantarum. - Copenhagen : Munksgaard Forlag. - 0031-9317 .- 1399-3054. ; 49:4, s. 477-486 Tidskriftsartikel (refereegranskat)
27.	Björn, Gunvor, et al. (författare) Light-induced lineardichroism in photoreversibly photochromic sensor pigments.” - IV. Lack of chromophore rotation in phycochrome b immobilized in vitro 1984 Ingår i: Physiologia Plantarum. - 0031-9317 .- 1399-3054. ; :60, s. 253-256 Tidskriftsartikel (refereegranskat)
28.	Björn, G S, et al. (författare) Action spectra for conversions of phycochrome c from Nostoc-muscorum 1978 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 43:3, s. 195-200 Tidskriftsartikel (refereegranskat)abstract The reversibly photochromic pigment, phycochrome c, was extracted from the blue-green alga Nostoc muscorum strain A. Action spectra were determined for in vitro conversions of the pigment from the short wavelength to the long wavelength form and vice versa. The action peak for the absorbance decrease at 650 nm is at 630 nm. During this decrease there is only a slight increase of the absorbance in the green region. Green and yellow light (maximum efficiency at 580 nm) completely restores absorbance at 650 nm. The observations are explained by the existence of three spectrally different forms of phycochrome c: Pc630 and Pc650 which equilibrate in darkness and Pc580 which is reversibly photoconvertible to Pc630. We have also measured the absorbance changes brought about by saturating irradiations with light of various wavelengths ("photostationary state spectrum"). Extreme photostationary states were obtained with about 650 nm and 500 nm light.
29.	Björn, G S, et al. (författare) Light-induced, dark-reversible color shifts in petals of Phlox 1985 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 64:4, s. 445-448 Tidskriftsartikel (refereegranskat)abstract Flowers of some Phlox (Phlox x paniculata L.) varieties undergo daily colour shifts, being blue in the early morning, turning red during the day, and returning to blue in the evening. The colour shift, which occurs only in the upper (adaxial) petal surfaces, is due to the daily changes in ambient light. In the laboratory, colour shifts could be induced by 2.5 h of ultraviolet, visible or far-red light and recorded by reflectance spectrophotometry. There are indications that irradiations with different kinds of light cause qualitatively different colour shifts, and that thus more than one photoreceptor pigment and more than one primary light reaction may be involved. The presence of phytochrome was demonstrated in petals of white Phlox flowers by in vivo transmission spectrophotometry. It is therefore possible that colour shifts in coloured Phlox flowers are mediated by phytochrome. Possibly the movement of ions (e.g. hydrogen ions) into or out of the vacuole (where the visible pigments are located) is affected by light absorption in a pigment in the tonoplast.
30.	Björn, Gunvor S, et al. (författare) Light-induced lineardichroism in photoreversibly photochromic sensor pigments - IV. Lack of chromophore rotation in phycochrome b immobilized in vitro. 1984 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 60, s. 253-256 Tidskriftsartikel (refereegranskat)abstract In photochromic pigments, immobilized on Sepharose beads to prevent reorientation of the molecules, linear absorption dichroism can be induced with plane‐polarized light. This phenomenon was used to study the relation between the carrier protein and the chromophore in the photochromic cyanobacterial pigment, phycochrome b, from Tolypothrix distorta var. symplocoides Hansgirg, strain UTEX 424 (formerly IUCC 424). It was found that the transition moment of the chromophore has the same direction with respect to the protein in the long‐wavelength and the short‐wavelength forms of phycochrome b. This contrasts to earlier results for phytochrome in higher plants, in which the transition moment was found to rotate 32° (or 180°—32°) when the long‐wavelength form was converted to the short‐wavelength form or vice versa.
31.	Björn, G S, et al. (författare) Photochromic pigments from blue-green algae - phycochrome-A, phycochrome-B and phycochrome-C 1976 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 36:4, s. 297-304 Tidskriftsartikel (refereegranskat)abstract Aqueous extracts of blue-green algae were fractionated by electrofocusing. In all algae investigated, fractions with isoelectric points at or near 4.6 showed photochromic behavior analogous to that of phytochrome, although they were sensitive to light of shorter wavelength. Three main types of photochromic pigments were found. Phycochrome a (in Tolypothrix distorta, Phormidium luridium, Nostoc muscorum 1453/12 and Anacystis nidulans) had 1 form absorbing maximally at about 590 nm (formed under red light) and 1 absorbing maximally at about 630 nm (formed under green light). Phycochrome b (in T. distorta) had 1 form absorbing maximally near 510 nm and 1 form absorbing maximally at 570 nm (formed in yellow-green and blue-green light, respectively). Phycochrome c (in N. muscorum A and probably in T. tenuis) had 1 form absorbing maximally at 650 nm (formed under green light) and 1 absorbing very weakly in the green region (formed under red light). The conversion of Phormidium phycochrome a from its red-absorbing form to its green-absorbing form caused the same spectral change as if an f-chromophore of phycocyanin were transformed into an s-chromophore. The quantum yield for this conversion was estimated to be 0.1, while the quantum yield for the reversion was estimated to be 0.4 on the assumption that the absorption coefficients were those of f- and s-chromophores. Phycochrome c was less light-sensitive than phycochromes a and b.
32.	Björn, G S, et al. (författare) Photochromic pigments in akinetes and pigment characteristics of akinetes in comparison with vegetative cells of Anabaena-Variabilis 1983 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 59:3, s. 493-500 Tidskriftsartikel (refereegranskat)abstract Since akinete germination is triggered by light and the action spectrum for this process has features in common with the spectra of the two photochromic pigments, phycochromes b and d, a search was made for the presence of these phycochromes in akinetes of the blue-green alga. Anabaena variabilis Kützing. Allophycocyanin-B was also looked for, since the action spectrum for akinete germination points to a possible participation of this pigment too. Isoelectric focusing was used for purification of the pigments. The different fractions were investigated for phycochromes b and d by measuring the absorbance difference spectra: for phycochrome b. 500 nm irradiated minus 570 nm irradiated, and for phycochrome d, 650 nm irradiated minus 610 nm irradiated. For determination of allophycocyanin-B. fourth derivative analysis of absorption spectra was made for some of the fractions from the isoelectric focusing column. Phycochrome b was also assayed for by measuring in vivo absorption difference spectra. The assays were positive for all three pigments. The complete photosynthetic pigment systems were also studied by in vivo fluorescence measurements on both akinetes and vegetative cells of Anabaena variabilis. Fluorescence emission and excitation spectra at selected emission wavelengths were measured at room temperature and liquid nitrogen temperature. The energy transfer from phycoerythrocyanin to phycocyanin is very efficient under all conditions, as is the energy transfer from phycocyanin to allophycocyanin at room temperature. At low temperature, however, phycocyanin is partly decoupled from allophycocyanin, particularly in the akinetes; the energy transfer from allophycocyanin to chlorophyll a is less efficient at low temperature in both types of cells, but especially in akinetes. Delayed light emission was measured for both types of cells and found to be very weak in akinetes compared to vegetative cells. From this study it would seem that akinetes lack an active photosystem II, although the 691 nm peak in the 570 nm excited low temperature fluorescence emission spectrum proves the presence of photosystem II chlorophyll, and also its energetic connection to the phycobilisomes.
33.	Björn, Lars Olof, et al. (författare) Imaging by delayed light-emission (phytoluminography) as a method for detecting damage to the photosynthetic system 1979 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 47:4, s. 215-222 Tidskriftsartikel (refereegranskat)abstract An improved apparatus for obtaining luminescence (delayed light emission) images of plants is described. It consists of a phosphoroscope equipped with an imaging lens and an electronic image intensifier. It is also equipped with light-sources for obtaining images with reflected light and fluorescence light. Damage to the photosynthetic system caused by virus, insects, high or low temperature, UV radiation, or herbicide, and also chloroplast senescence as part of a normal developmental process, can be followed by this non-destructive method. In many cases changes which are not visible in fluorescence images are clearly seen in luminescence images. (Leaves of Hibiscus sp., Oxalis tetraphylla, Nicotiana glutinosa with a tobacco mosaic virus infection, Fagus sylvatica with midge gall and Polypodium vulgare were used.).
34.	Björn, Lars Olof (författare) Light-induced linear dichroism in photoreversibly photochromic sensor pigments 5. Reinterpretation of the experiments on invivo action dichroism of phytochrome 1984 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 60:3, s. 369-372 Tidskriftsartikel (refereegranskat)
35.	Björn, Lars Olof (författare) Measurement of light gradients and spectral regime in plant-tissue with a fiber optic probe - reply 1986 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 67:3, s. 494-497 Tidskriftsartikel (refereegranskat)
36.	Björn, Lars Olof (författare) State of protochlorophyll and chlorophyll in corn roots 1976 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 37:3, s. 183-184 Tidskriftsartikel (refereegranskat)abstract The protochlorophyll(ide) present in primary roots of dark-grown corn (Zea mays) seedlings has an in vivo absorption maximum at 634 nm. Red light converts the pigment to chlorophyll(ide) a with an absorption maximum at 675 nm.
37.	Blomqvist, Lisa A., 1978, et al. (författare) Proteomic analysis of the etioplast inner membranes of wheat (Triticum aestivum) by two-dimensional electrophoresis and mass spectrometry 2006 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 128:2, s. 368-381 Tidskriftsartikel (refereegranskat)abstract The proteome of the etioplast inner membranes (EPIM) of dark-grown wheat leaves (Triticum aestivum L.) was mapped as an essential part of studies on plastid differentiation. Proteins were separated by two-dimensional gel electrophoresis and analysed with mass spectrometry (MS). Over 200 protein spots were resolved and visualized by Coomassie blue staining. More than 100 spots were submitted for subsequent mass spectrometry analyses by matrix-assisted laser desorption ionizationtime of flight (MALDI-ToF) MS, electrospray tandem MS (ESI-MS/MS) or liquid chromatographymass spectrometry (LC-MS/MS). There were 46 identified spots, from which at least 21 different proteins were identified. Among these were FtsH proteases and the peptidyl-prolyl cistrans isomerase TLP40, as well as chloroplast coupling factor subunits and extrinsic subunits of photosystem II (PSII). Of special interest is the NADPH:protochlorophyllide oxidoreductase (POR), which is the predominant protein of prolamellar bodies, where it accumulates in a highly stable ternary complex with protochlorophyllide and NADPH. This complex is known to play an important role in the formation and dispersal of prolamellar bodies. Five different isoforms of POR, with different pI values, were identified. We discuss the possibility of these isoforms being differently phosphorylated as part of the regulation of PORpigment complexes. The proteome mapping of EPIM is a crucial step in the understanding of the light-dependent transition of etioplasts to chloroplasts, and provides a basis for functional studies on factors influencing the greening process.
38.	Bolay, Paul, et al. (författare) Tailoring regulatory components for metabolic engineering in cyanobacteria 2024 Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 176:3 Forskningsöversikt (refereegranskat)abstract The looming climate crisis has prompted an ever-growing interest in cyanobacteria due to their potential as sustainable production platforms for the synthesis of energy carriers and value-added chemicals from CO2 and sunlight. Nonetheless, cyanobacteria are yet to compete with heterotrophic systems in terms of space-time yields and consequently production costs. One major drawback leading to the low production performance observed in cyanobacteria is the limited ability to utilize the full capacity of the photosynthetic apparatus and its associated systems, i.e. CO2 fixation and the directly connected metabolism. In this review, novel insights into various levels of metabolic regulation of cyanobacteria are discussed, including the potential of targeting these regulatory mechanisms to create a chassis with a phenotype favorable for photoautotrophic production. Compared to conventional metabolic engineering approaches, minor perturbations of regulatory mechanisms can have wide-ranging effects.
39.	BORODIN, V, et al. (författare) THE EFFECT OF LIGHT QUALITY ON THE INDUCTION OF EFFICIENT PHOTOSYNTHESIS UNDER LOW CO2 CONDITIONS IN CHLAMYDOMONAS-REINHARDTII AND CHLORELLA-PYRENOIDOSA 1994 Ingår i: Physiologia Plantarum. - 0031-9317 .- 1399-3054. ; 92:2, s. 254-260 Tidskriftsartikel (refereegranskat)abstract The effect of blue and red light on the adaptation to low CO2 conditions was studied in high-CO2 grown cultures of Chlorella pyrenoidosa (82T) and Chlamydomonas reinhardtii (137(+)) by measuring O-2 exchange under various inorganic carbon (C-i) concentrations. At equal photosynthetic photon flux density (PPFD), blue light was more favourable for adaptation in both species, compared to red light. The difference in photosynthetic oxygen evolution between cells adapted to low C-i under blue and red light was more pronounced when oxygen evolution was measured under low C-i compared to high C-i conditions. The effect of light quality on adaptation remained for several hours. The different effects caused by blue and red light was observed in C. pyrenoidosa over a wide range of PPFD with increasing differences at increasing PPFD. The maximal difference was obtained at a PPFD above 1 500 mu mol m(-2) s(-1). We found no difference in the extracellular carbonic anhydrase activity between blue- and red light adapted cells. The light quality effect recorded under C-i-limiting conditions in C. reinhardtii cells adapted to air, was only 37% less when instead of pure blue light red light containing 12.5% of blue light (similar PPFD as blue light) was used during adaptation to low carbon. This indicates that in addition to affecting photosynthesis, blue light affected a sensory system involved in algal adaptation to low C-i conditions. Since the affinity for C-i of C. pyrenoidosa and C. reinhardtii cells adapted to air under blue light was higher than that of cells adapted under red light, we suggest that induction of some component(s) of the C-i accumulating mechanism is regulated by the light quality.
40.	Brelsford, Craig C., et al. (författare) Do UV‐A radiation and blue light during growth prime leaves to cope with acute high light in photoreceptor mutants of Arabidopsis thaliana? 2019 Ingår i: Physiologia Plantarum. - : Blackwell Publishing. - 0031-9317 .- 1399-3054. ; 165:3, s. 537-554 Tidskriftsartikel (refereegranskat)abstract We studied how plants acclimated to growing conditions that included combinations of blue light (BL) and ultraviolet (UV)‐A radiation, and whether their growing environment affected their photosynthetic capacity during and after a brief period of acute high light (as might happen during an under‐canopy sunfleck). Arabidopsis thaliana Landsberg erecta wild‐type were compared with mutants lacking functional blue light and UV photoreceptors: phototropin 1, cryptochromes (CRY1 and CRY2) and UV RESISTANT LOCUS 8 (uvr8). This was achieved using light‐emitting‐diode (LED) lamps in a controlled environment to create treatments with or without BL, in a split‐plot design with or without UV‐A radiation. We compared the accumulation of phenolic compounds under growth conditions and after exposure to 30 min of high light at the end of the experiment (46 days), and likewise measured the operational efficiency of photosystem II (ϕPSII, a proxy for photosynthetic performance) and dark‐adapted maximum quantum yield (Fv/Fm to assess PSII damage). Our results indicate that cryptochromes are the main photoreceptors regulating phenolic compound accumulation in response to BL and UV‐A radiation, and a lack of functional cryptochromes impairs photosynthetic performance under high light. Our findings also reveal a role for UVR8 in accumulating flavonoids in response to a low UV‐A dose. Interestingly, phototropin 1 partially mediated constitutive accumulation of phenolic compounds in the absence of BL. Low‐irradiance BL and UV‐A did not improve ϕPSII and Fv/Fm upon our acute high‐light treatment; however, CRYs played an important role in ameliorating high‐light stress.
41.	Brodelius, M, et al. (författare) Immunolocalization of the saposin-like insert of plant aspartic proteinases exhibiting saposin C activity. Expression in young flower tissues and in barley seeds 2005 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 125:4, s. 405-418 Tidskriftsartikel (refereegranskat)abstract The plant- specific insert ( PSI) of cypro11 gene- encoding cyprosin, an aspartic proteinase from Cynara cardunculus, has been cloned by polymerase chain reaction ( PCR) into a bacterial expression vector. A rearranged form of this PSI in which the N- and C- terminal sequences were permutated to make it more similar to the structural arrangement observed in saposins was also cloned and expressed in the same system. The biological activities of the two purified recombinant proteins were compared to those of human saposins B and C. The proteins showed similar activity to saposin C, i. e. capacity to activate human glucosylceramidase. At a concentration of 5 mu M, wild- type PSI, saposin C, and rearranged PSI activated human glucosylceramidase two-, three-, and five- fold, respectively. The K-m for 4- methylumbelliferyl beta-glucopyranoside was around 7 mM in the presence of any of the three activators ( 5 mM). The neurotropic activity using NS20Y cells and lipid- binding properties of the plant recombinant proteins were tested. The two plant proteins showed lipid- binding properties similar to those of saposins but did not have any effect on neurite outgrowth. Immunolocalization of PSI showed its expression in protective tissues in flower meristem - protodermis, in C. cardunculus and embryonic root cap and coleorhiza in mature barley grains - as well as husk, pericarp, and the aleurone layer. Possible biological functions suggested for the plant homologue to saposins besides the general activation of enzymes involved in lipid metabolism would be involvement in plant defence.
42.	Brosché, Mikael, et al. (författare) Molecular events following perception of ultraviolet-B radiation by plants 2003 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 117:1, s. 1-10 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.
43.	Brunoni, Federica, et al. (författare) Control of root meristem establishment in conifers 2019 Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 165:1, s. 81-89 Tidskriftsartikel (refereegranskat)abstract The evolution of terrestrial plant life was made possible by the establishment of a root system, which enabled plants to migrate from aquatic to terrestrial habitats. During evolution, root organization has gradually progressed from a very simple to a highly hierarchical architecture. Roots are initiated during embryogenesis and branch afterward through lateral root formation. Additionally, adventitious roots can be formed post-embryonically from aerial organs. Induction of adventitious roots (ARs) forms the basis of the vegetative propagation via cuttings in horticulture, agriculture and forestry. This method, together with somatic embryogenesis, is routinely used to clonally multiply conifers. In addition to being utilized as propagation techniques, adventitious rooting and somatic embryogenesis have emerged as versatile models to study cellular and molecular mechanisms of embryo formation and organogenesis of coniferous species. Both formation of the embryonic root and the AR primordia require the establishment of auxin gradients within cells that coordinate the developmental response. These processes also share key elements of the genetic regulatory networks that, e.g. are triggering cell fate. This minireview gives an overview of the molecular control mechanisms associated with root development in conifers, from initiation in the embryo to post-embryonic formation in cuttings.
44.	Buffoni Hall, Roberta, et al. (författare) Water- and temperature-dependence of DNA damage and repair in the fruticose lichen Cladonia arbuscula ssp mitis exposed to UV-B radiation 2003 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 118:3, s. 371-379 Tidskriftsartikel (refereegranskat)abstract The induction of cyclobutane pyrimidine dimers (CPDs) by ultraviolet-B radiation (UV-B, 280-315 nm) and repair mechanisms were studied in the lichen Cladonia arbuscula ssp. mitis exposed to different temperatures and water status conditions. In addition, the development and repair of CPDs were studied in relation to the different developmental stages of the lichen thallus podetial branches. Air-dried lichen thalli exposed to UV-B radiation combined with relatively high visible light (HL, 800 mumol m(-2) s(-1); 400-700 nm) for 7 days showed a progressive increase of CPDs with no substantial repair, although HL was present during and after irradiation with UV-B. Fully hydrated lichen thalli, that had not been previously exposed to UV-B radiation for 7 days, were given short-term UV-B radiation treatment at 25degreesC, and accumulated DNA lesions in the form of CPDs, with repair occurring when they were exposed to photoreactivating conditions (2 h of 300 mumol m(-2)s(-1), 400-700 nm). A different pattern was observed when fully hydrated thalli were exposed to short-term UV-B radiation at 2degreesC, in comparison with exposure at 25degreesC. High levels of CPDs were induced at 2degreesC under UV-B irradiation, without significant repair under subsequent photoreactivating light. Likewise, when PAR (300 mumol m(-2)s(-1) ) and UV-B radiation were given simultaneously, the CPD levels were not lowered. Throughout all experiments the youngest, less differentiated parts of the lichen thallus - namely 'tips', according to our arbitrary subdivision - were the parts showing the highest levels of CPD accumulation and the lowest levels of repair in comparison with the older thallus tissue ('stems'). Thus the experiments showed that Cladonia arbuscula ssp. mitis is sensitive to UV-B irradiation in the air-dried state and is not able to completely repair the damage caused by the radiation. Furthermore, temperature plays a role in the DNA damage repairing capacity of this lichen, since even when fully hydrated, C. arbuscula ssp. mitis did not repair DNA damage at the low temperatures.
45.	Businge, Edward, et al. (författare) The effect of carbohydrates and osmoticum on storage reserve accumulation and germination of Norway spruce somatic embryos 2013 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 149, s. 273-285 Tidskriftsartikel (refereegranskat)abstract Somatic embryogenesis (SE) represents a useful experimental system for studying the regulatory mechanisms of embryo development. In this study, the effect of carbohydrates and osmoticum on storage reserve accumulation and germination of Norway spruce [Picea abies (L.) Karst] somatic embryos were investigated. Using time lapse photography, we monitored development from proliferation of proembryogenic masses (PEMs) to maturation of somatic embryos in two P. abies cell lines cultured on two maturation treatments. A combination of sugar assays, metabolic and proteomic analyses were used to quantify storage reserves in the mature somatic embryos. The maturation treatment containing a nonpermeating osmoticum, polyethylene glycol (PEG, 7.5%) and maltose (3%) as the carbohydrate gave significantly high maturation and low germination frequencies of somatic embryos compared to the treatment with only 3% sucrose. Somatic embryos treated with 3% sucrose contained high levels of sucrose, raffinose and late embryogenesis abundant (LEA) proteins. These compounds are known to be involved in the acquisition of desiccation tolerance during seed development and maturation. In addition the sucrose treatment significantly increased the content of starch in the somatic embryos while the maltose and PEG treatment resulted in somatic embryos with a high content of storage proteins. The high levels of sucrose, raffinose and LEA proteins in the embryos treated with 3% sucrose suggest that sucrose may improve the germination of somatic embryos by promoting the acquisition of desiccation tolerance.
46.	Böddi, Béla, et al. (författare) Protochlorophyllide forms in non-greening epicotyls of dark-grown pea (Pisum sativum) 1994 Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 92:1, s. 160-170 Tidskriftsartikel (refereegranskat)
47.	Calderon, Robert H. (författare) A lycophyte's plight when the light is too bright 2022 Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 174:2 Tidskriftsartikel (refereegranskat)abstract Plants cannot go to the store to buy sunscreen when they get too much sunlight. Instead, they use a suite of molecular processes that turn excess absorbed light energy into heat so that it can be harmlessly dissipated. These photoprotective processes collectively fall under the umbrella term “nonphotochemical quenching of chlorophyll fluorescence” which is often shortened to “nonphotochemical quenching” or “NPQ.” If excess sunlight is not dissipated via NPQ, it can result in damage and inactivation of the photosynthetic machinery, specifically photosystem II (PSII), that is energetically costly to repair. While many years of research have led to the identification of proteins and pigments involved in NPQ and of different pathways of NPQ, the underlying molecular mechanisms that plants use to dissipate excess light energy still remain unclear.
48.	Calderon, Robert H. (författare) In the Spotlight : Salt and peppers — two spices meet to turn up the heat 2023 Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 175:4 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
49.	Calderon, Robert H. (författare) More than just a pair of blue genes : how cyanobacteria adapt to changes in their light environment 2020 Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 170:1, s. 7-9 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Cyanobacteria require light to perform photosynthesis, but not all colors of light are equally useable for them. In particular, blue light‐grown cyanobacterial strains, including the well‐studied model organism Synechocystis sp. PCC 6803 (Synechocystis), have been observed to exhibit slower growth rates than white or red light‐grown cells. In this issue of Physiologia Plantarum, Luimstra et al. (2020) have attempted to understand why cyanobacterial cells suffer under blue light. They measured the molecular and genetic responses of Synechocystis cells to being shifted from white light to blue light. They found that blue light‐grown cells make changes that lead to a redistribution of energy flow between the two photosystems that power photosynthesis. These findings could help researchers identify avenues for optimizing photosynthesis in cyanobacterial species, a group of organisms which show great promise as potential solar‐powered factories for the production of biofuels and other high‐value products.
50.	Calderon, Robert H. (författare) Red LEDs leave plants singing the blues 2020 Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 169:1, s. 7-9 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)

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