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  • Author or Editor: H. Lepeduš x
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The effect of extensive urban dust pollution, caused mainly by road traffic, on some biochemical and structural characteristics of current-year Norway spruce (Picea abies L. Karst.) needles was investigated. Two categories of needle samples were formed according to the data about the pollution levels obtained from the Croatian National Institute of Public Health: less and more affected. Apoplastic guaiacol peroxidases were used as the molecular stress markers. Peroxidase activity was doubled in more affected needles compared with the less affected ones. Also, the electrophoretic pattern of samples extracted from more affected needles revealed the expression of additional isozyme band, which could be attributed to the activation of detoxifying mechanisms. Anatomy of more affected needles was changed as well. Necrosis of needle mesophyll usually connected with the stomata was the most outstanding character. Also, distortions of sieve cells were present in the same needle samples indicating possible disturbances in mineral nutrition. The obtained results showed that needles of Norway spruce trees that are exposed to the higher pollution level undergoes to both structural and biochemical changes. Besides of the described changes, the investigated spruce trees are able to survive in more polluted environment as well.

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The vegetative buds and later on young needles as well as needles formed in spring previous year of Picea abieswere used in the experimental work. Extracted proteins were determined spectrophotometrically and the amount of dry weight was measured. The data revealed that the dry weight of needles formed in spring previous year was about three times higher than in the vegetative buds at the beginning of investigations. During the sampling period the dry weight in those needles was keeping nearly the same level (39-54%). The increase in dry weight was noticed in the young needles 5-6 weeks after vegetative buds burst. The amount of total soluble proteins in the needles formed previous year was about 140 mg/g of dry weight and it was uniformed during the investigation period. In the vegetative buds the amount of proteins was three times higher than in needles. But, the concentration starts to decrease just before bursting of the vegetative buds as well as during next 2 or 3 weeks when young shoot proliferated. After this decreasing period amount of proteins in newly formed needles briefly reached (in 2 weeks period) the level as it was in vegetative buds. In the following period the decrease of water amount as well as the protein amount in young needles was observed.

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The photosynthetic performance of developing spruce ( Picea abies L. Karst.) needles was investigated. As revealed by previous reports, the biosynthesis of chlorophylls and carotenoids was not following the characteristic chloroplast ultrastructure building up during needle elongation process. The aim of our study was to investigate photosynthetic capability (evaluated by oxygen evolution and chlorophyll a fluorescence kinetics measurements), the dynamics of chloroplast pigments biosynthesis and the expression of major photosynthetic proteins as well as to find out possible correlation between components of issue. Low amounts of chlorophylls and carotenoids, LHC II and Rubisco LSU were detected in the embryonic shoot of vegetative buds. Although PS II was functional, oxygen production was not sufficient to compensate for respiration in the same developmental stage. The light compensation point of respiration was successively lowered during the needle elongation. Nevertheless the significant increase in photosynthetic pigments as well as the high level of expression of LHC II and Rubisco LSU proteins was observed in the later stages of needle development. Our results suggest that, besides light, some other environmental factors could be critical for producing fully functional chloroplasts in rapidly growing young needles.

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Vegetative buds represent developmental stage of Norway spruce (Picea abies L. Karst.) needles where chloroplast biogenesis and photosynthetic activity begin. We used the analyses of polyphasic chlorophyll a fluorescence rise (OJIP) to compare photosystem II (PSII) functioning in vegetative buds and fully photosynthetically active mature current-year needles. Considerably decreased performance index (PIABS) in vegetative buds compared to needles pointed to their low photosynthetic efficiency. Maximum quantum yield of PSII (Fv/Fm) in buds was slightly decreased but above limited value for functionality indicating that primary photochemistry of PSII is not holdback of vegetative buds photosynthetic activity. The most significant difference observed between investigated developmental stages was accumulation of reduced primary quinine acceptor of PSII (QA ) in vegetative buds, as a result of its limited re-oxidation by passing electrons to secondary quinone acceptor, QB. We suggest that reduced electron transfer from QA to QB could be the major limiting factor of photosynthesis in vegetative buds.

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The changes of vacuolar polyphenols appearance in the mesophyll cells of Black pine needles during the second year of their development and the connection of these changes with distance from the pollution source were studied as needle S-content started to decrease two years after the SO 2 concentration in the air approached the level that could be considered as low near the Plomin thermal power plant. Investigation plot was arranged in zones: I — less than 10 km, II — 10 to 20 km, III — 20 to 30 km around the power plant. Seven forms of vacuolar polyphenols were detected: two forms of granules — fine and larger ones, globules, thin and thick ribbons, ribbons occupying the whole cell and homogeneous mass. In the zone I the dominating were ribbon like polyphenols. The most abundant polyphenols in the zone II was the globular type while in the zone III besides large and fine granules thin ribbons were, also, well abundant. According to the linkage clustering zones I and II are more similar to each other than zone III, based on the abundance of different polyphenols types. At this point the hypothesis that vacuolar polyphenols could be considered as some kind of “memory” molecules in the environmental monitoring of the SO 2 effects on plants can be made.

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Acta Alimentaria
Authors: V. Bušić, S. Kovač, D. Gašo-Sokač and H. Lepeduš

The aim of this study was to examine antioxidant activities of the anthocyanins isolated from different sour cherry ( Prunus cerasus ) cultivars. DPPH radical method and photochemiluminescence detection method were employed. The effect of isolated anthocyanins on peroxidase activity was also investigated. In the DPPH method, methanol extract of isolated anthocyanins was employed and results showed the highest radical-scavenging activity of anthocyanins isolated from one genotype of Cigančica cherry (genotype VN 10–11), Petrovaradinska and Oblačinska cherry cultivar. Integral antioxidative capacity was determined by luminometry (Photochem), calculating the ascorbic acid equivalents. The best reducing power was shown by anthocyanins isolated from Maraska and Petrovaradinska cherry cultivars. Peroxidase activity of fresh plant material was determined and the influence of anthocyanins on peroxidase activity was investigated.

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Acta Biologica Hungarica
Authors: Tanja Pfeiffer, Ivna Štolfa, M. Žanić, N. Pavičić, Vera Cesar and H. Lepeduš

Olive is one of the most important cultivated Mediterranean plants. In order to determine the differences in frost resistance of two, two-year-old olive cultivars (Olea europaea cv. Leccino and cv. Oblica) growing on different types of nutrient substrates (soil and coconut fibres), the trees were exposed to low temperature (−5 °C) in the dark. It was shown that low temperature caused an increase in H2O2 concentration, level of lipid peroxidation and carbonyl protein content in both cultivars and on both nutrient substrates, respectively. The CAT and APX activities significantly varied depending on the cultivar, the nutrient substrate type and the time of exposure to low temperature. Cv. Oblica and cv. Leccino growing on coconut fibres showed a better antioxidative response to low temperature probably due to the higher nitrogen and phosphorus concentration established in this type of nutrient substrate. That positive antioxidative response determined on coconut fibres was more pronounced in leaves of cv. Leccino.

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