Susanne Somersalo

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Glycine betaine is an osmoprotectant found in many organisms, including bacteria and higher plants. The bacterium Escherichia coli produces glycine betaine by a two-step pathway where choline dehydrogenase (CDH), encoded by betA, oxidizes choline to betaine aldehyde which is further oxidized to glycine betaine by the same enzyme. The second step, conversion(More)
The photoinhibition of photosynthesis at chilling temperatures was investigated in cold-acclimated and unhardened (acclimated to +18° C) spinach (Spinacia oleracea L.) leaves. In unhardened leaves, reversible photoinhibition caused by exposure to moderate light at +4° C was based on reduced activity of photosystem (PS) II. This is shown by determination of(More)
The effects of moderate light at chilling temperature on the photosynthesis of unhardened (acclimated to +18° C) and hardened (cold-acclimated) spinach (Spinacea oleracea L.) leaves were studied by means of fluorescence-induction measurements at 20° C and 77K and by determination of quantum yield of O2 evolution. Exposure to 550 μmol photons·m-2·s-1 at +4°(More)
The role of high light stress in a natural environment was studied on spinach plants (Spinacia oleracea L. cv. Wolter) grown in the field during the winter season. Fluorescence induction (at 293 K and 77 K) of leaves was used to characterize the stress effects. Night frost with minimum temperatures between - 1.5°C and -7.5°C (i.e. above the'frost killing(More)
The effect of foliar-applied glycinebetaine (GB) on chloroplast ultrastructure, the amount of chlorophyll and proteins and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activity in stressed tomato leaves were analysed. Initial, and total activity and activation state state of RuBPCO were also measured. RuBPCO activities, chloroplast area, and the(More)
Freezing and thawing of leaves of herbaceous plants leads to damage when the freezing temperature falls below a certain tolerance limit, which depends on the plant species and state of acclimation. Such damage is expressed as an irreversible inhibition of photosynthesis observed after thawing. In frost-damaged leaves the capacity of photosynthetic reactions(More)
Both fibre hemp (Cannabis sativa L.) and linseed (Linum usitatissimum L.) produce bast fibres in their stems. The bast fibre can be considered the main product of fibre hemp, whereas it is a by-product of linseed cultivation. Today, bast fibres are finding use in various technical applications, as in geotextiles, composites, compression moulded parts, paper(More)
Seventeen morphological and physiological characteristics of three Avena barbata L. populations from Israel were measured in order to define possible combinations explaining adaptation of these populations to different precipitation, temperature and altitude regimes. Five genotypes from each A. barbata populations were collected from Ashqelon (31°63′N, low(More)
The leaves of chilling-sensitive pumpkin (Cucurbita pepo L.) showed symptoms reminiscent of photoinhibition when kept for 4 days at 5 degrees C in moderate light. A decrease was observed in the variable part of chlorophyll alpha fluorescence, apparent quantum yield, and maximum rate of O(2) evolution. Chloroplast whole-chain electron transport activity(More)
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