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Introduction
Skills and Expertise
Publications
Publications (137)
There is a need for non-invasive monitoring of temporal and spatial variation in hydration and photosynthetic activity of red-listed poikilohydric autotrophs. Here, we simultaneously recorded kinetics in RGB-colors (photos), reflectance spectra, water content, maximal (F V /F M), and effective quantum yield of PSII (Φ PSII) during desiccation in fo...
Lichens often grow in microhabitats where they absorb more light than they can use for fixing carbon, and this excess energy can cause the formation of harmful reactive oxygen species (ROS). Lichen mycobionts can reduce ROS formation by synthesizing light-screening pigments such as melanins in the upper cortex, while the photobionts can dissipate e...
Elevated levels of ionizing and non-ionizing radiation may co-occur and pose cumulative hazards to biota. However, the combined effects and underlying toxicity mechanisms of different types of radiation in aquatic plants remain poorly understood. The present study aims to demonstrate how different combined toxicity prediction approaches can collect...
Background
There is limited information on the effect of environment on vegetative growth in everbearing (EB) strawberry ( Fragaria x ananassa Duch.) and its comparison with the situation in seasonal flowering types.
Methods
We investigated the effects of photoperiod (daylengths of 10 and 20 h) and temperature (12, 19 and 26 ℃) on leaf growth, dry...
Lichen extinction occurs at rapid rates as a result of human activity, although species could potentially be rescued by conservation management based on ecophysiological knowledge. The boreal old forest cyanolichen Erioderma pedicellatum currently occurs in few sites worldwide. To protect it from extinction, it is essential to learn more about it....
Lichens are frequently used as indicators of air-borne depositions, yet the differential effect of different mineral nutrients on lichen growth is still poorly understood. Here we quantify relative lichen growth rates (RGR) in representatives of three functional groups (chloro-, cephalo-, cyanolichens; Xanthoria parietina, Lobaria pulmonaria, Lobar...
High relative humidity (RH) perturbs plant growth, stomatal functioning and ABA homeostasis, but the role of ABA in this physiological regulation is equivocal. To determine the role(s) of ABA in plant responses to high RH, wild‐type (WT) tomato and barley plants and their respective ABA‐deficient mutants flacca and Az34 (which are mutated in the sa...
There is little knowledge about photosynthesis in everbearing strawberry cultivars. We therefore grew three everbearing strawberry cultivars in daylight phytotron compartments at temperatures of 9, 15, 21 and 27°C and photoperiods of 10 h (SD) and 20 h (LD). After three weeks, the rates of dark respiration and photosynthesis and their acclimation w...
Main conclusion
During desiccation, both apparent electron transport rate (ETRapp) and photosynthetic CO2 uptake peak when external water has evaporated. External water, causing suprasaturation, weakens the strong correlation between ETRapp and CO2 uptake.
Abstract
Lichens are poikilohydric organisms passively regulated by ambient conditions. In t...
Lichens often grow in microhabitats where they are exposed to severe abiotic stresses such as desiccation and temperature extremes. They are also often exposed to levels of light that are greater than lichen photobionts can use in carbon fixation. Unless regulated, excess energy absorbed by the photobionts can convert ground state oxygen to reactiv...
Due to the high number of chemicals and species, it is not feasible to assess the risk of every chemical to human and ecosystems. Cost-effective alternative ecotoxicity testing strategies with reduced needs for laboratory animal use are highly demanded. New Approach Methodologies (NAMs), such as high-throughput screening and high-content toxicogeno...
Main conclusion
UVB radiation caused irradiance-dependent and target-specific responses in non-UVB acclimated Lemna minor. Conceptual toxicity pathways were developed to propose causal relationships between UVB-mediated effects at multiple levels of biological organisation.
Abstract
Macrophytes inhabit waterways around the world and are used in hy...
We quantified annual growth rate and loss of Bryoria capillaris and Usnea dasopoga transplants on Picea abies on parts of lower branches in the inner versus outer canopy in small, medium and tall trees in hemiboreal forests. Light at branches in the inner canopy was 2.7 x (for Bryoria capillaris) and 2.0 x (for Usnea dasopoga) higher than the liche...
Powdery mildews can be controlled by brief exposure to ultraviolet (UV) radiation with devastating effect on their developmental stages including conidia germination. The treatment effect can be impaired by subsequent exposure to UV-A/blue light. UV-A/blue light-activated photolyase may be responsible for this and therefore we tested the function o...
Some lichenized ascomycetes synthesize melanic pigments in their upper cortices when
exposed to ultraviolet light and high solar radiation. Our previous work showed that melanized chloro- and cyanolichens from both high light and more shaded habitats were less photoinhibited than pale ones during controlled exposure to high light. However, protecti...
Main conclusion
Photobiont type influences the relative humidity threshold at which photosystem II activates in green algal lichens.
Abstract
Water vapor uptake alone can activate photosynthesis in lichens with green algal photobionts. However, the minimum relative humidity needed for activation is insufficiently known. The objective of this study...
Main conclusion
Persistent DNA damage in gamma-exposed Norway spruce, Scots pine and Arabidopsis thaliana, but persistent adverse effects at the organismal and cellular level in the conifers only.
Gamma radiation emitted from natural and anthropogenic sources may have strong negative impact on plants, especially at high dose rates. Although previou...
Exposure to ambient UV-B radiation may prime protective responses towards various stressors in plants, though information about interactive effects of UV-B and potentially stressful gamma radiation levels is scarce. Here, we aimed to test whether UV-B exposure could prime acclimatisation mechanisms contributing to tolerance to low-moderate gamma ra...
Many species of lichenized ascomycetes are capable of synthesizing darkly colored melanin pigments by polymerizing phenolic compounds. Available data suggest that different clades of lichens produce various kinds of melanins, with N2-fixing Peltigeralean lichens producing N-rich DOPA or “eumelanins” and lichens from other orders producing N-poor “a...
High dose rates of ionizing radiation have been reported to cause adverse effects such as reduction in reproduction and growth, and damage to protein and lipids in primary producers. However, the relevant effects of ionizing radiation are still poorly understood in aquatic plants. This study was intended to characterize the biological effects and m...
Main conclusion
Chlorophyll fluorescence, infrared gas exchange and photoinhibition data consistently show that vulpinic acid in L. vulpina functions as a strong blue light screening compound.
The cortical lichen compounds, parietin, atranorin, usnic acid and melanins are known to screen photosynthetically active radiation (PAR), thereby protecting...
Some lichenized ascomycetes synthesize melanic pigments when exposed to ultraviolet light and high solar radiation. Here, we used chlorophyll fluorescence in order to test the effect of melanisation on the ability of the lichens Cetraria islandica, Lobaria pulmonaria, Peltigera aphthosa, P. membranacea, Pseudocyphellaria gilva, and Sticta sublimbat...
Growth in high relative air humidity (RH, > 85%) affects plant morphology and causes diminished response to stomatal closing signals. Many greenhouses are prone to high RH conditions, which may negatively affect production and post-harvest quality. UV radiation induces stomatal closure in several species, and facilitates disease control. We hypothe...
Retention of trees after logging is a method of preserving epiphytic lichens; however, epiphytes’ responses to logging disturbance are insufficiently known. We aimed to characterize four viability measures — effective PSII yield (a proxy for photosynthesis), maximal photosystem II efficiency (FV/FM; a proxy for photoinhibition), chlorophyll a conte...
Blue and yellow sticky traps equipped with blue light emitting diodes (LEDs) were evaluated for their attractiveness to the western flower thrips (Frankliniella occidentalis Pergande) and compared to similar traps without light in two greenhouses with commercial production of either mixed herbs or Alstroemeria cut flowers. Blue traps were more attr...
This editorial is inspired by discussions that took place during a workshop held in June 2017 at the Global Change Research Institute, in Brno in the Czech Republic. The workshop was organised by Dr Otmar Urban and Prof Marcel Jansen, under the auspices of UV4Plants, the International Association for Plant UV Research (https://www.uv4plants.org/),...
Lichen photobionts in situ have an extremely UV-B tolerant photosystem II efficiency (Fv/Fm). We have quantified the UV-B-screening offered by the mycobiont and the photobiont separately. The foliose lichens Nephroma arcticum and Umbilicaria spodochroa with 1: intact or 2: removed cortices were exposed to 0.7 Wm⁻² UV-BBE for 4 h. Intact thalli expe...
Lichen photobionts in situ have an extremely UV-B tolerant photosystem II efficiency (Fv/Fm). We have quantified the UV-B-screening offered by the mycobiont and the photobiont separately. The foliose lichens Nephroma arcticum and Umbilicaria spodochroa with 1: intact or 2: removed cortices were exposed to 0.7 Wm-2 UV-BBE for 4 h. Intact thalli expe...
Greenhouse production of poinsettia calls for strict control of morphological parameters, which may be achieved through the use of chemical growth retardants. Use of such chemicals is becoming restricted thus alternative methods for growth control are needed. Here the effects of UV radiation were tested on Euphorbia pulcherrima (Willd ex. Klotzch)...
Quackgrass is a problematic agricultural weed in the temperate zones of the world and is difficult to control without herbicides or intensive tillage. However, it may be possible to control quackgrass with less environmental impact by combining multiple low-intensity control methods. A pot experiment was conducted in July to October 2012 and repeat...
Lichens are considered freezing tolerant, although few species have been tested. Growth, a robust measure of fitness integrating processes in all partners of a lichen thallus, has not yet been used as a viability measure after freezing. We compared relative growth rates (RGR) after freezing with short-term viability measures of photo- and mycobiont...
Identifying lichen traits that influence hydration and photosynthetic reactivation kinetics in humid air provides insight into niche preferences. Water vapor uptake and concurring reactivation of PSII efficiency (Fv/Fm) were monitored at high temporal resolution by means of programmed balance measurements and chlorophyll fluorescence imaging during...
Standard chemical toxicity testing guidelines using aquatic plant Lemna minor have been developed by several international standardisation organisations. Although being highly useful for regulatory purposes by focusing on traditional adverse endpoints, these tests provide limited information about the toxic mechanisms and modes of action (MoA). The...
Chlorophyll a fluorescence is often used to estimate various types of damage in lichens. In order to optimize the output and improve interpretations of such measurements the protocol for pretreatment and measuring is important. To study the effects of measurement conditions, the lichens Lobaria pulmonaria , L. scrobiculata , Xanthoria parietina and...
Controlled environment chamber experiments at Petri dish level were conducted to examine the wavelength and dose dependent efficacy of ultraviolet (UV) radiation, the recovery action potential of optical radiation applied concomitantly/subsequently to effective UV treatment, and the lapse time between UV treatment and subsequent exposure to recover...
During the past two decades, significant spread of the perennial weeds Juncus effusus (soft rush) and Juncus conglomeratus (compact rush) in coastal parts of Norway seems to have coincided with an observed rise in winter temperatures. This study investigated the frost tolerance (LT50) and effects of moderate frost exposure on rush plant regrowth ov...
The old forest lichen Lobaria pulmonaria synthesizes melanic pigments when exposed to ultraviolet light and high solar radiation. Here, we tested the effect of melanisation on photosynthetic efficiency. Melanisation effectively reduces high-light stress in lichen photobionts, as the photobionts of melanised thalli are healthy, based on chlorophyll...
We quantified relative growth rates (RGR) in shade-adapted and melanin-deficient thalli of Cetraria islandica and Lobaria pulmonaria cultivated in short-term growth chamber experiments with and without UV-B radiation. In the first experiment done under optimal PAR (125 μmol m⁻² s⁻¹), but high UV-B radiation (1 W m⁻²), UV-B radiation significantly r...
Information on the involvement of elongation-controlling hormones, particularly gibberellin (GA), in UV-B modulation of stem elongation and leaf growth, is limited. We aimed to study the effect of UV-B on levels of GA and indole-3-acetic acid (IAA) as well as involvement of GA in UV-B inhibition of stem elongation and leaf expansion in pea. Reduced...
This study aims to quantify the size-dependency of important hydration traits in Lobaria amplissima, L. pulmonaria and L. virens sampled in sympatric populations on deciduous tree trunks in southern Norway, and to discuss possible implications of species-specific traits for the ecological niches of these old forest cephalolichens. Traits measured w...
By fluorescence imaging, we quantified how hydration traits and thallus size determine the duration of photosynthetic activity during drying in light and darkness for sympatric populations of three epiphytic old forest cephalolichens differing in specific thallus mass (STM) and growth form. Maximal PS II efficiency (FV/FM) during drying in darkness...
Ionizing radiation have been reported to cause biological impact in different organisms including both autotrophs and heterotrophs. Upon exposure of aquatic plants, high intensity of ionizing radiation can cause reduction of reproduction and growth, biological damage to DNA and other biomolecules. However, the physiological responses and mechanisms...
Ionising radiation (IR) in environment is a nature phenomenon where effects may also be enhanced by radiation from human activity such as nuclear power plants accident, nuclear medicine and weapon tests. Among different ionising radiation types, the toxicity of high dose gamma () radiation is frequently studied in different organisms such as mamma...
To test the hypotheses that (1) protective mycobiont tissues and/or (2) medullary UV-B-absorbing carbon-based secondary compounds (CBSCs) protect lichen photobionts against UV-B radiation, we quantified cortical UV-transmittance and ran a three-way factorial lab experiment with (1) three UV radiation regimes, (2) photobiont layers with/without a sc...
The aquatic environment is continuously exposed to ionizing radiation from both natural and anthropogenic sources, making the characterization of ecological and health risks associated with radiation of large importance. Microalgae represent the main source of biomass production in the aquatic ecosystem, thus becoming a highly relevant biological m...
Edited by BS Ripley Ultraviolet radiation (UV) is well known to affect plant growth and development and to vary with latitude and altitude. The knowledge about the effect of high UV levels at high altitudes close to the equator on plant productivity is scarce. By using UV-transmitting and UV-blocking films, the impact of solar UV on growth and prod...
In order to investigate the relationship between environmental conditions and vegetative growth and reproductive development in the strawberry, freshly rooted runner plants of the cultivar ‘Sonata’ were grown in a phytotron at temperatures of 12, 18 and 24◦C and photoperiods of 10 h short day (SD) and 20 h long day (LD) for 31 d and harvested at 10...
Tyrosinases are a widespread family of multicopper oxidase enzymes. In our earlier work, we identified the presence of tyrosinases in lichenized Ascomycetes based on their substratum specificity, sensitivity to inhibitors and molecular mass. Here, we present a more detailed characterization of a tyrosinase from the lichen Lobaria pulmonaria . We al...
In order to improve growth chamber protocols for lichens, we tested the effect of 1) wet filter paper versus self-drained nets as a substratum for lichens, and 2) gradual versus abrupt transitions between dark and light periods. For Lobaria pulmonaria (L.) Hoffm. cultivated on nets, RGR increased by 60% compared to those on wet papers, whereas abru...
Relative growth rates (RGR) and carbon-based secondary compounds (CBSCs) were quantified in four dominant terricolous arctic-alpine mat-forming lichens with different preferences for snow cover. The aim was to evaluate the effects of snow depth, and thus snow cover duration, on lichen growth and performance. The species,
Alectoria ochroleuca
,
Flav...
Disease-suppressive effects of nighttime applications of ultraviolet-B (UV-B) were investigated at two irradiance levels (0.8 or 1.6 W/m2) in strawberry and rosemary plants inoculated with Podosphaera aphanis or Golovinomyces biocellatus, respectively. Plants were exposed to each irradiance level every third night for 18 min; every night for 6 min;...
Lichens are useful monitoring organisms for heavy metal pollution. They are high in carbon based secondary compounds (CBSCs) among which some may chelate heavy metals and thus increase metal accumulation. This study quantifies CBSCs in four epiphytic lichens transplanted for 6months on stands along transects from a highway in southern Norway to sea...
In the lab, we exposed three foliose lichen species, Lobaria pulmonaria, Parmelia sulcata and Xanthoria aureola, to 0, 0.01, 0.2, and 0.6 M NaCl in combinations with copper and zinc (0, 10, 100, 500 μM). High salt concentrations adversely affected the lichen membrane integrity as measured by conductivity methods, whereas the potential photosystem I...
This growth chamber experiment evaluates how temperature and humidity regimes shape soluble carbohydrate pools and growth rates in lichens with different photobionts.
We assessed soluble carbohydrates, relative growth rates ( RGRs ) and relative thallus area growth rates ( RT A GRs ) in Parmelia sulcata (chlorolichen), Peltigera canina (cyanolichen...
Epiphytic lichens, comprising an important biodiversity component with significant functions in old boreal forests, are susceptible to logging. Leaving retention trees may partly compensate for the adverse effects of logging, but the impact of logging season on retained lichens is unknown. To identify the least harmful logging season seen from an e...
This study aims to quantify dispersal of airborne traffic-related elemental pollutants and concurring responses – relative growth rate (RGR), maximal quantum yield of PSII (Fv/Fm), and chlorophylls (Chl ab) – in four epiphytic lichens (Lobaria pulmonaria, Parmelia sulcata, Ramalina farinacea, Usnea dasopoga). Lichens were transplanted from 25 Septe...
Infestation by Juncus effusus and Juncus conglomeratus causes a serious reduction in forage quality along the western coastline in Norway. Timing of treatments, for example cutting to reduce photosynthate return to the weeds, is crucial for successful and cost-effective weed control. However, the effect may depend on changes in regrowth capacity ov...
Pendulous lichens dominate canopies of boreal forests, with dark Bryoria species in the upper canopy vs. light Alectoria and Usnea species in lower canopy. These genera offer important ecosystem services such as winter forage for reindeer and caribou. The mechanism behind this niche separation is poorly understood. We tested the hypothesis that spe...
Photosynthesis was compared in two cyanobacterial lichens (Lobaria hallii and Peltigera praetextata) and two green algal lichens (Lobaria pulmonaria and Peltigera leucophlebia) exposed to red, green or blue light. Cyanolichens had substantially lower photosynthetic CO2 uptake and O2 evolution than the green algal lichens in blue light, but slightly...
This study demonstrates that the spectral quality of radiation sources applied with ultraviolet-B (UV-B) (background radiation) affects the suppression of cucumber powdery mildew (Podosphaera xanthii) by UV-B. Suppression provided by daily UV-B exposure of 1W/m2 for 10 min was greatest in the presence of red light, or by a complete lack of backgrou...
Plants grown in Norwegian greenhouses during winter synthesise low amounts of anthocyanins and flavonols (colourless flavonoids). Higher content of anthocyanins enhances the red colour in lettuce and improves the external quality and marketability of the product. The flavonoids may also benefit consumer health due to their anti-oxidative and presum...
Abstract with poster presentation
This study investigates how hydration during light and dark periods influences growth in two epiphytic old forest lichens, the green algal Lobaria pulmonaria and the cyanobacterial L. scrobiculata. The lichens were cultivated in growth chambers for 14 days (200 μmol m−1 s−2; 12 h photoperiod) at four temperature regimes (25/20 °C, 21/16 °C, 13/8 °C...
Chemical plant growth retardants (PGRs) are used to control height of greenhouse grown plants. Increasing environmental awareness has strongly promoted interest in alternative methods. Since UV-B is known to reduce shoot elongation, the use of supplemental UV-B radiation or UV-B and UV-A-transmitting cladding material such as F-clean appears highly...
Experiments were conducted to determine the optimum dose of UV-B (280- 315 nm) required for suppression of powdery mildews of rose (Rosa × hybrida) and cucumber (Cucumis sativus). Daily exposure to UV-B during dark at 1.2 W m-2 for 2 to 5 min substantially suppressed powdery mildew in 'Toril' pot roses without measurable damage to the plants. Compa...
Alterations in light quality affect plant morphogenesis and photosynthetic responses but the effects vary significantly between species. Roses exhibit an irradiance dependent flowering control but knowledge on light quality responses is scarce. In this study we analyzed, the responses in morphology, photosynthesis and flowering of Rosa × hybrida to...
The functional roles of secondary lichen compounds are reviewed with focus on sun-screening and herbivore-deterring functions. Hypotheses on ecological functions can be tested because lichen compounds can nondestructively be extracted from air-dry lichens with 100% acetone. Substantial evidence supports a sun-screening function of cortical compound...
Suppression of cucumber powdery mildew by UV-B is affected by background light quality Suthaparan, A., Stensvand, A., Solhaug, k.A., Torre. S., Telfer, K. H., Ruud, A.K., Cadle-Davidson, L., Mortensen, L.M., Gadoury, D.M., Seem, R.C., and Gislerød, H.R. Corresponding author- Aruppillai Suthaparan email- aruppillai.suthaparan@nmbu.no Brief (5-10 min...