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Untersuchungen von Genexpression und physiologischen Abwehrreaktionen an gesunden und geschädigten Buchen
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Untersuchungen von Genexpression und physiologischen Abwehrreaktionen an gesunden und geschädigten Buchen
No full textQuantification of ozone influx and apoplastic ascorbate content in needles of Norway spruce trees (Picea abies L., Karst) at high altitude
No full textThe objective of the present study was to investigate whether peak concentrations of ozone can deplete the apoplastic ascorbate pool of needles from Norway spruce trees (Picea abies L. Karst.) and, thereby, contribute to damage to forest trees. Twigs of forest trees grown at high altitude (1950m above sea level; Mt Patscherkofel, Austria) were enclosed in situ in chambers and fumigated for 5‐5 or 17 h with ozone concentrations ranging from 60 to 798 nmol mol−1. Adjacent branches were fumigated with filtered air. Ozone influx into the foliage ranging from 1‐7 to 17nmolm−2s−1 had little effect on whole‐needle ascorbate or glutathione contents. However, apoplastic ascorbate decreased by about 30% when the needles were exposed to environmentally relevant ozone concentrations and increased about 3‐fold at higher ozone concentrations. This response suggests the induction of ascorbate as a protective system and may also be important under field conditions. Needles of spruce trees from high altitude that were exposed to chronically increased ozone concentrations contained significantly higher apoplastic ascorbate concentrations than needles from spruce trees from lower altitudes with lower mean atmospheric ozone concentrations. The results show that peak concentrations of ozone do not act in spruce via a depletion of the apoplastic ascorbate pool
Impact of cadmium on young plants of Populus euphratica and P. × canescens, two poplar species that differ in stress tolerance
No full textPopulus euphratica is a salt tolerant species, and Populus × canescens is a salt sensitive species. Because stress tolerance is mediated by an array of overlapping defense mechanisms, we hypothesized that P. euphratica would confer co-tolerance to heavy metal stress. To test this hypothesis, both poplar species were exposed to 50 μM Cd for 24 h in hydroponic solutions. For the analyses of stress symptoms in roots and leaves, we used nutrient element concentrations and transcriptional responses of 28 stress- and defense-related genes. The roots showed strong Cd accumulation, but less in P. euphratica than in P. × canescens. In contrast, the leaves of P. euphratica accumulated 10-times more Cd than those of P. × canescens. Cd-stressed leaves of P. euphratica displayed water loss and wilting. Both species revealed contrasting transcriptional responses of defense genes to Cd stress. In P. euphratica, glutathione reductase, dehydroascorbate reductase and glutathione S-transferases of the theta and tau classes showed increases in transcript levels in response to Cd, pointing to oxidative stress and a strong activation of detoxification mechanisms. In contrast, in P. × canescens transcript levels of genes involved in signaling, activation of, and protection from drought stress were significantly increased including glutathione S-transferases of the phi class (early response to dehydration). Our data show that P. euphratica salt tolerance does not confer Cd tolerance and suggest that failure to activate early protection contributed to higher Cd sensitivity in P. euphratica than in P. × canescens
Innovative Holzprodukte und Holzwerkstoffe aus nachhaltig produziertem Buchen- und Küstentannenholz
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