TY - JOUR AB - Plants emit diverse volatile organic compounds (VOCs) from their leaves and roots for protection against biotic and abiotic stress. An important signaling cascade activated by aboveground herbivory is the jasmonic acid (JA) pathway that stimulates the production of VOCs. So far it remains unclear if the activation of this pathway also leads to enhanced VOC emissions from conifer roots, and how the interplay of above- and belowground defenses in plants are affected by multiple stressors. Therefore, we simultaneously analyzed needle and root VOC emissions of Picea abies saplings, as well as CO2 and H2O fluxes in response to aboveground JA treatment, heat stress and their interaction in a controlled climate chamber experiment. Continuous online VOC measurements by PTR-TOF-MS showed an inverse pattern of total needle and root VOC emissions, when plants were treated with JA and heat. While needle sesquiterpene emissions increased nine-fold one day after JA application, total root VOC emissions decreased. This was mainly due to reduced emissions of acetone and monoterpenes by roots. In response to aboveground JA treatment, root total carbon emitted as VOCs decreased from 31% to only 4%. While VOC emissions aboveground increased, net CO2 assimilation strongly declined due to JA treatment, resulting in net respiration during the day. Interestingly, root respiration was not affected by aboveground JA application. Under heat the effect of JA on VOC emissions of needles and roots was less pronounced. The buffering effect of heat on VOC emissions following JA treatment points towards an impaired defense reaction of the plants under multiple stress. Our results indicate efficient resource allocation within the plant to protect threatened tissues by a rather local VOC release. Roots may only be affected indirectly by reduced belowground carbon allocation, but are not involved directly in the JA-induced stress response. AU - Meischner, M.* AU - Dumberger, S.* AU - Daber, L.E.* AU - Haberstroh, S.* AU - Kreuzwieser, J.* AU - Schnitzler, J.-P. AU - Werner, C.* C1 - 70760 C2 - 55883 CY - Great Clarendon St, Oxford Ox2 6dp, England TI - Jasmonic acid and heat stress induce high volatile organic compound emissions in Picea abies from needles, but not from roots. JO - Tree Physiol. PB - Oxford Univ Press PY - 2024 SN - 0829-318X ER - TY - JOUR AB - Metabolomics studies are becoming increasingly common for understanding how plant metabolism responds to changes in environmental conditions, genetic manipulations and treatments. Despite the recent advances in metabolomics workflow, the sample preparation process still limits the high-throughput analysis in large-scale studies. Here, we present a highly flexible robotic system that integrates liquid handling, sonication, centrifugation, solvent evaporation and sample transfer processed in 96-well plates to automatize the metabolite extraction from leaf samples. We transferred an established manual extraction protocol performed to a robotic system, and with this, we show the optimization steps required to improve reproducibility and obtain comparable results in terms of extraction efficiency and accuracy. We then tested the robotic system to analyze the metabolomes of wild-type and four transgenic silver birch (Betula pendula Roth) lines under unstressed conditions. Birch trees were engineered to overexpress the poplar (Populus × canescens) isoprene synthase and to emit various amounts of isoprene. By fitting the different isoprene emission capacities of the transgenic trees with their leaf metabolomes, we observed an isoprene-dependent upregulation of some flavonoids and other secondary metabolites as well as carbohydrates, amino acid and lipid metabolites. By contrast, the disaccharide sucrose was found to be strongly negatively correlated to isoprene emission. The presented study illustrates the power of integrating robotics to increase the sample throughput, reduce human errors and labor time, and to ensure a fully controlled, monitored and standardized sample preparation procedure. Due to its modular and flexible structure, the robotic system can be easily adapted to other extraction protocols for the analysis of various tissues or plant species to achieve high-throughput metabolomics in plant research. AU - Bertic, M. AU - Zimmer, I. AU - Andrés-Montaner, D.* AU - Rosenkranz, M. AU - Kangasjärvi, J.* AU - Schnitzler, J.-P. AU - Ghirardo, A. C1 - 68174 C2 - 54618 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 1855-1869 TI - Automatization of metabolite extraction for high-throughput metabolomics: Case study on transgenic isoprene-emitting birch. JO - Tree Physiol. VL - 43 IS - 10 PB - Oxford Univ Press PY - 2023 SN - 0829-318X ER - TY - JOUR AB - Drought and salt exposure are among the most prevalent and severe abiotic stressors causing serious agricultural yield losses, alone and in combination. Little is known about differences and similarities in the effects of these two stress factors on plant metabolic regulation, particularly on nitrogen metabolism. Here, we studied the effects of water deprivation and salt exposure on water relations and nitrogen metabolites in leaves and roots of date palm seedlings. Both, water deprivation and salt exposure had no significant effects on plant water content or stable carbon (C) and nitrogen (N) isotope signatures. Significant effects of water deprivation on total C and N concentrations were only observed in roots, i.e., decreased total C and increased total N concentrations. Whereas salt exposure initially decreased total C and increased total N concentrations significantly in roots, foliar total C concentration was increased upon prolonged exposure. Initially C/N ratios declined in roots of plants from both treatments and upon prolonged salt exposure also in the leaves. Neither treatment affected soluble protein and structural N concentrations in leaves or roots, but resulted in the accumulation of most amino acids, except for glutamate and tryptophan, which remained stable, and serine, which decreased, in roots. Accumulation of the most abundant amino acids, lysine and proline, was observed in roots under both treatments, but in leaves only upon salt exposure. This finding indicates a similar role of these amino acids as compatible solutes in the roots in response to salt und drought, but not in the leaves. Upon prolonged treatment, amino acid concentrations returned to levels found in unstressed plants in leaves of water deprived, but not salt exposed, plants. The present results show both water deprivation and salt exposure strongly impact N metabolism of date palm seedlings, but in a different manner in leaves and roots. AU - Du, B.* AU - Winkler, J.B. AU - Ache, P.* AU - White, P.J.* AU - Dannenmann, M.* AU - Alfarraj, S.* AU - Albasher, G.* AU - Schnitzler, J.-P. AU - Hedrich, R.* AU - Rennenberg, H.* C1 - 67123 C2 - 53484 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 587-596 TI - Differences of nitrogen metabolism in date palm (Phoenix dactylifera) seedlings subjected to water deprivation and salt exposure. JO - Tree Physiol. VL - 43 IS - 4 PB - Oxford Univ Press PY - 2022 SN - 0829-318X ER - TY - JOUR AB - Infection with the necrotrophic fungus Diplodia sapinea is among the economically and ecologically most devastating diseases of conifers in the northern hemisphere accelerated by global climate change. The present study aims to characterize the changes mediated by D. sapinea infection on its pine host (Pinus sylvestris L.) that lead to the death of its needles. For this purpose, we performed an indoor infection experiment and inoculated shoot tips of pine seedlings with virulent D. sapinea. The consequences for foliar traits, including the phytohormone profile were characterized at both the metabolite and transcriptome level. Our results showed that D. sapinea infection strongly affected foliar levels of most phytohormones and impaired a multitude of other metabolic and structural foliar traits, such as ROS scavenging. Transcriptome analysis revealed that these changes are partially mediated via modified gene expression by fungal exposure. D. sapinea appears to overcome defense reactions of its pine host by reprogramming gene expression and post-transcriptional controls that determine essential foliar metabolic traits such as the phytohormone profile, cell wall composition and antioxidative system. AU - Hu, B.* AU - Liu, Z.* AU - Haensch, R.* AU - Mithöfer, A.* AU - Peters, F.S.* AU - Vornam, B.* AU - Messerer, M. AU - Mayer, K.F.X. AU - Wirén, N.* AU - Rennenberg, H.* C1 - 66995 C2 - 53363 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 611-629 TI - Diplodia sapinea infection reprograms foliar traits of its pine (Pinus sylvestris L.) host to death. JO - Tree Physiol. VL - 43 IS - 4 PB - Oxford Univ Press PY - 2022 SN - 0829-318X ER - TY - JOUR AB - Woody species invasions are a major threat to native communities with intensified consequences during increased periods of summer drought as predicted for the future. Competition for growth-limiting nitrogen (N) between native and invasive tree species might represent a key mechanism underlying the invasion process, because soil water availability and N acquisition of plants are closely linked. To study whether the traits of invasive species provide an advantage over natives in Central Europe in the competition for N under drought, we conducted a greenhouse experiment. We analyzed the responses of three native (i.e., Fagus sylvatica L., Quercus robur L. and Pinus sylvestris L.) and two invasive woody species (i.e., Prunus serotina Ehrh. and Robinia pseudoacacia L.) to competition in terms of their organic and inorganic N acquisition, as well as allocation of N to N pools in the leaves and fine roots. In our study, competition resulted in reduced growth and changes in internal N pools in both native and invasive species mediated by the physiological characteristics of the target species, the competitor, as well as soil water supply. Nitrogen acquisition, however, was not affected by competition indicating that changes in growth and N pools were rather linked to the remobilization of stored N. Drought led to reduced N acquisition, growth and total soluble protein-N levels, while total soluble amino acid-N levels increased, most likely as osmoprotectants as an adaptation to the reduced water supply. Generally, the consequences of drought were enhanced with competition across all species. Comparing the invasive competitors, P. serotina was a greater threat to the native species than R. pseudoacacia. Furthermore, deciduous and coniferous native species affected the invasives differently, with the species-specific responses being mediated by soil water supply. AU - Bueno, A.* AU - Pritsch, K. AU - Simon, J.* C1 - 61662 C2 - 50139 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 343-357 TI - Responses of native and invasive woody seedlings to combined competition and drought are species-specific. JO - Tree Physiol. VL - 41 IS - 3 PB - Oxford Univ Press PY - 2021 SN - 0829-318X ER - TY - JOUR AB - Drought negatively impacts growth and productivity of plants, particularly in arid and semi-arid regions. Although drought events can take place in summer and winter, differences on the impact of drought on physiological processes between seasons are largely unknown. The aim of this study was to elucidate metabolic strategies of date palms in response to drought in summer and winter season. To identify such differences, we exposed date palm seedlings to a drought-recovery regime, both in simulated summer and winter climate. Leaf hydration, carbon discrimination (∆13C), primary and secondary metabolite composition and contents were analyzed. Depending on season, drought differently affected physiological and biochemical traits of the leaves. In summer, drought induced significantly decreased leaf hydration, concentrations of ascorbate, most sugars, primary and secondary organic acids, as well as phenolic compounds, while thiol, amino acid, raffinose and individual fatty acid contents were increased compared to well-watered plants. In winter, drought had no effect on leaf hydration, ascorbate and fatty acids contents, but resulted in increased foliar thiol and amino acid levels as observed in summer. Compared to winter, foliar traits of plants exposed to drought in summer only partly recovered after re-watering. Memory effects on water relations, primary and secondary metabolites seem to prepare foliar traits of date palms for repeated drought events in summer. Apparently, a well-orchestrated metabolic network, including the anti-oxidative system, compatible solutes accumulation and osmotic adjustment, and maintenance of cell membrane stability strongly reduces the susceptibility of date palms to drought. These mechanisms of drought compensation may be more frequently required in summer. AU - Du, B.* AU - Kruse, J.* AU - Winkler, J.B. AU - Alfarraj, S.* AU - Albasher, G.* AU - Schnitzler, J.-P. AU - Ache, P.* AU - Hedrich, R.* AU - Rennenberg, H.* C1 - 61495 C2 - 50290 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 1685-1700 TI - Metabolic responses of date palm (Phoenix dactylifera L.) leaves to drought differ in summer and winter climate. JO - Tree Physiol. VL - 41 IS - 9 PB - Oxford Univ Press PY - 2021 SN - 0829-318X ER - TY - JOUR AB - Mycorrhizal fungi play an important role for the nitrogen (N) supply of trees. The influence of different mycorrhizal types on N acquisition in tree-tree interactions is, however, not well understood, particularly with regard to the competition for growth-limiting N. We studied the effect of competition between temperate forest tree species on their inorganic and organic N acquisition in relation to their mycorrhizal type (i.e., arbuscular mycorrhiza or ectomycorrhiza). In a field experiment, we quantified net N uptake capacity from inorganic and organic N sources using 15N/13C stable isotopes for arbuscular mycorrhizal tree species (i.e., Acer pseudoplatanus L., Fraxinus excelsior L., and Prunus avium L.) as well as ectomycorrhizal tree species (i.e., Carpinus betulus L., Fagus sylvatica L., and Tilia platyphyllos Scop.). All species were grown in intra- and interspecific competition (i.e., monoculture or mixture). Our results showed that N sources were not used complementarily depending on a species´ mycorrhizal association, but their uptake rather depended on the competitor indicating species-specific effects. Generally, ammonium was preferred over glutamine and glutamine over nitrate. In conclusion, our findings suggest that inorganic and organic N acquisition of the studied temperate tree species is less regulated by mycorrhizal association, but rather by the availability of specific N sources in the soil as well as the competitive environment of different tree species. AU - Reuter, R.* AU - Ferlian, O.* AU - Tarkka, M.* AU - Eisenhauer, N.* AU - Pritsch, K. AU - Simon, J.* C1 - 61963 C2 - 50539 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 2096-2108 TI - Tree species rather than type of mycorrhizal association drives inorganic and organic nitrogen acquisition in tree-tree interactions. JO - Tree Physiol. VL - 41 IS - 11 PB - Oxford Univ Press PY - 2021 SN - 0829-318X ER - TY - JOUR AB - Competitive interactions between native tree seedlings and exotic grasses frequently hinder forest restoration. We investigated the consequences of competition with exotic grasses on the growth and net nitrogen (N) uptake capacity of native rainforest seedlings used for reforestation depending on soil N availability and N source. Tree seedlings and grasses were grown in the greenhouse in different competition regimes (one tree species vs one grass species) and controls (grass monocultures or single tree seedlings) at low and high soil N. After 8 weeks, we quantified net N uptake capacity using N-15-labelled organic (i.e., glutamine and arginine) and inorganic (i.e., ammonium and nitrate) N sources and biomass indices. Depending on soil N availability, we observed different species-specific responses to growth and N acquisition. Tree seedlings generally increased their net N uptake capacity in response to competition with grasses, although overall seedling growth was unaffected. In contrast, the responses to competition by the grasses were species-specific and varied with soil N availability. The different N acquisition strategies suggest the avoidance of competition for N between trees and grasses. Overall, the results highlight that quantifying underlying mechanisms of N acquisition complements the information on biomass allocation as a measure of responses to competition, particularly with varying environmental conditions. AU - Bueno, A.* AU - Greenfield, L.* AU - Pritsch, K. AU - Schmidt, S.* AU - Simon, J.* C1 - 54731 C2 - 45787 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 404-416 TI - Responses to competition for nitrogen between subtropical native tree seedlings and exotic grasses are species-specific and mediated by soil N availability. JO - Tree Physiol. VL - 39 IS - 3 PB - Oxford Univ Press PY - 2018 SN - 0829-318X ER - TY - JOUR AB - Rhizospheric nitric oxide (NO) and carbon dioxide (CO2) are signalling compounds known to affect physiological processes in plants. Their joint influence on tree nitrogen (N) nutrition, however, is still unknown. Therefore, this study investigated, for the first time, the combined effect of rhizospheric NO and CO2 levels on N uptake and N pools in European beech (Fagus sylvatica L.) seedlings depending on N availability. For this purpose, roots of seedlings were exposed to one of the nine combinations (i.e., low, ambient, high NO plus CO2 concentration) at either low or high N availability. Our results indicate a significant effect of rhizospheric NO and/or CO2 concentration on organic and inorganic N uptake. However, this effect depends strongly on NO and CO2 concentration, N availability and N source. Similarly, allocation of N to different N pools in the fine roots of beech seedlings also shifted with varying rhizospheric gas concentrations and N availability. AU - Dong, F.* AU - Simon, J.* AU - Rienks, M.* AU - Lindermayr, C. AU - Rennenberg, H.* C1 - 45362 C2 - 37302 CY - Oxford SP - 910-920 TI - Effects of rhizopheric Nitric Oxide (NO) on N uptake in Fagus sylvatica seedlings depend on soil CO2 concentration, soil N availability and N source. JO - Tree Physiol. VL - 35 IS - 8 PB - Oxford Univ Press PY - 2015 SN - 0829-318X ER - TY - JOUR AB - In the present study, biogenic volatile organic compound (BVOC) emissions and photosynthetic gas exchange of salt-sensitive (Populus x canescens (Aiton) Sm.) and salt-tolerant (Populus euphratica Oliv.) isoprene-emitting and non-isoprene-emitting poplars were examined under controlled high-salinity and high-temperature and -light episode ('sunfleck') treatments. Combined treatment with salt and sunflecks led to an increased isoprene emission capacity in both poplar species, although the photosynthetic performance of P. × canescens was reduced. Indeed, different allocations of isoprene precursors between the cytosol and the chloroplast in the two species were uncovered by means of (13)CO2 labeling. Populus × canescens leaves, moreover, increased their use of 'alternative' carbon (C) sources in comparison with recently fixed C for isoprene biosynthesis under salinity. Our studies show, however, that isoprene itself does not have a function in poplar survival under salt stress: the non-isoprene-emitting leaves showed only a slightly decreased photosynthetic performance compared with wild type under salt treatment. Lipid composition analysis revealed differences in the double bond index between the isoprene-emitting and non-isoprene-emitting poplars. Four clear metabolomics patterns were recognized, reflecting systemic changes in flavonoids, sterols and C fixation metabolites due to the lack/presence of isoprene and the absence/presence of salt stress. The studies were complemented by long-term temperature stress experiments, which revealed the thermotolerance role of isoprene as the non-isoprene-emitting leaves collapsed under high temperature, releasing a burst of BVOCs. Engineered plants with a low isoprene emission potential might therefore not be capable of resisting high-temperature episodes. AU - Behnke, K. AU - Ghirardo, A. AU - Janz, D.* AU - Kanawati, B. AU - Esperschütz, J. AU - Zimmer, I. AU - Schmitt-Kopplin, P. AU - Niinemets, U.* AU - Polle, A.* AU - Schnitzler, J.-P. AU - Rosenkranz, M. C1 - 26058 C2 - 32048 SP - 562-578 TI - Isoprene function in two contrasting poplars under salt and sunflecks. JO - Tree Physiol. VL - 33 IS - 6 PB - Oxford Univ. Press PY - 2013 SN - 0829-318X ER - TY - BOOK AB - In recent years, it has become possible to inhibit constitutive production of biogenic volatile organic compounds (BVOC) in trees by genetic engineering. In addition, the trait for constitutive emissions has been introduced in several previously non-emitting herbaceous model organisms and crops. Research on these genetically engineered organisms has demonstrated that eliminating terpenes (syn. terpenoids or isoprenoids) emission reduces stress tolerance, while enhancing emissions often increases abiotic and biotic stress tolerance. In this chapter, the progress in terpene engineering work is reviewed, and the advantages of, changes in and obstacles related to genetically modified (GM) trees are discussed. We start by introducing the reader to terpene biosynthesis and the efforts undertaken to manipulate that process, we further review past attempts to repress and overexpress terpene synthases in herbs and trees, and finally describe the current achievements and suggest future possibilities in the field of terpene emission engineering. AU - Rosenkranz, M. AU - Schnitzler, J.-P. A2 - Niinemets, U.* ; Monson, R.K.* C1 - 23364 C2 - 31971 CY - Heidelberg SP - 95-118 TI - Genetic enigineering of bvoc emissions from trees. JO - Tree Physiol. VL - 5 PB - Springer PY - 2013 SN - 0829-318X ER - TY - JOUR AB - Interspecific gene flow is common in oaks. In the Mediterranean, this process produced geographical differentiations and new species, which may have contributed to the diversification of the production of volatile terpenes in the oak species of this region. The endemic North African deciduous oak Quercus afares (Pomel) is considered to be a stabilized hybrid between the evergreen Quercus suber (L.) and the deciduous Quercus canariensis (Willd.), presumably being monoterpene and isoprene emitters, respectively. In a common garden experiment, we examined the terpene emission capacities, terpene synthase (TPS) activities and nuclear genetic markers in 52 trees of these three oak species. All but one of the Q. suber and Q. canariensis trees were found to be genetically pure, whereas most Q. afares trees possessed a mixed genotype with a predominance of Q. suber alleles. Analysis of the foliar terpene emissions and TPS activities revealed that all the Q. canariensis trees strongly produced isoprene while all the Q. suber trees were strong monoterpene producers. Quercus afares trees produced monoterpenes as well but at more variable and significantly lower rates, and with a monoterpene pattern different than that observed in Q. suber. Among 17 individuals tested, one Q. afares tree emitted only an insignificant amount of terpenes. No mixed isoprene/monoterpene emitter was detected. Our results suggest that the capacity and pattern of volatile terpene production in Algerian Q. afares populations have strongly diverged from those of its parental species and became quantitatively and qualitatively reduced, including the complete suppression of isoprene production. AU - Welter, S.* AU - Bracho-Nuñez, A.* AU - Mir, C.* AU - Zimmer, I. AU - Kesselmeier, J.* AU - Lumaret, R.* AU - Schnitzler, J.-P. AU - Staudt, M.* C1 - 10855 C2 - 30385 SP - 1082-1091 TI - The diversification of terpene emissions in Mediterranean oaks: Lessons from a study of Quercus suber, Quercus canariensis and its hybrid Quercus afares. JO - Tree Physiol. VL - 32 IS - 9 PB - Oxford Univ. Press PY - 2012 SN - 0829-318X ER - TY - JOUR AB - In this study, the effects of different light intensities either in direct sunlight or in the shade crown of adult beech (Fagus sylvatica L.) trees on delta C-13 and Delta O-18 were determined under ambient (1 x O-3) and twice-ambient (2 x O-3) atmospheric ozone concentrations during two consecutive years (2003 and 2004). We analysed the isotopic composition in leaf bulk, leaf cellulose, phloem and xylem material and related the results to (a) meteorological data (air temperature, T and relative humidity, RH), (b) leaf gas exchange measurements (stomatal conductance, g(s); transpiration rate, E; and maximum photosynthetic activity, A(max)) and (c) the outcome of a steady-state evaporative enrichment model. delta C-13 was significantly lower in the shade than in the sun crown in all plant materials, whilst Delta O-18 was increased significantly in the shade than in the sun crown in bulk material and cellulose. Elevated ozone had no effect on delta C-13, although Delta O-18 was influenced by ozone to varied degrees during single months. We observed significant seasonal changes for both parameters, especially in 2004, and also significant differences between the study years. Relating the findings to meteorological data and gas exchange parameters, we conclude that the differences in Delta O-18 between the sun and the shade crown were predominantly caused by the Peclet effect. This assumption was supported by the modelled Delta O-18 values for leaf cellulose. It was demonstrated that independent of RH, light-dependent reduction of stomatal conductance (and thus transpiration) and of A(max) can drive the pattern of Delta O-18 increase with the concomitant decrease of delta C-13 in the shade crown. The effect of doubling ozone levels on time-integrated stomatal conductance and transpiration as indicated by the combined analysis of Delta O-18 and delta C-13 was much lower than the influence caused by the light exposure. AU - Gessler, A.* AU - Löw, M.* AU - Heerdt, C.* AU - Op de Beeck, M.* AU - Schumacher, J.* AU - Grams, T.E.* AU - Bahnweg, G. AU - Ceulemans, R.* AU - Werner, H.* AU - Matyssek, R.* AU - Rennenberg, H.* AU - Haberer, K.* C1 - 2106 C2 - 26362 CY - Oxford SP - 1349-1365 TI - Within-canopy and ozone fumigation effects on δ¹³C and Δ¹⁸O in adult beech (Fagus sylvatica) trees: Relation to meteorological and gas exchange parameters. JO - Tree Physiol. VL - 29 IS - 11 PB - Oxford Univ Press PY - 2009 SN - 0829-318X ER - TY - JOUR AB - We determined changes in cell-wall peroxidase activities and isoform patterns in response to wounding in seedlings of Prosopis tamarugo Phil. (an endemic species of the Atacama Desert) and Prosopis chilensis (Mol.) Stuntz (a native species of central Chile), to assess tolerance to predation. In seedlings of both species, the maximal increase in peroxidase activity occurred 48 h after wounding, reaching three times the control value in P. tamarugo and twice the control value in P. chilensis. The activity of ionically bound cell-wall peroxidases increased only locally in wounded embryonic axes, whereas the activity of soluble peroxidases increased systemically in unwounded cotyledons. Analysis of ionic peroxidases by isoelectrofocusing revealed two groups of peroxidases in the cell walls of both species: four distinct acidic isoforms and a group of basic isoforms. In response to wounding, there was a large increase in activity of the acidic isoforms in P. tamarugo, whereas there was an increase in the activity of the basic isoforms in P. chilensis. In P. chilensis, the wound-induced increase in activity of the basic isoforms corresponded with one of the two isoforms detected in P. tamarugo prior to wounding. Experiments with protein and RNA synthesis inhibitors indicated that a preexisting basic peroxidase is activated in P. chilensis after wounding. Assays of ionically bound peroxidase activity with four different substrates corroborated the differences found in isoform patterns between species. In P. tamarugo, the largest increases in activity were found with ortho-phenylenediamine and ferulic acid as substrates, whereas in P. chilensis the largest increase in activity was found with guaiacol as substrate. Because the same basic cell-wall peroxidase that accumulated after wounding in P. chilensis was present in P. tamarugo prior to wounding, and the activity of acidic cell-wall peroxidases increased after wounding in P. tamarugo but not in P. chilensis, we conclude that P. tamarugo is more tolerant to wound stress than P. chilensis. AU - Lehner, G. AU - Cardemil, L.* C1 - 23369 C2 - 31071 SP - 443-452 TI - Differences in wound-induced changes in cell-wall peroxidase activities and isoform patterns between seedlings of Prosopis tamarugo and Prosopis chilensis. JO - Tree Physiol. VL - 23 IS - 7 PB - Oxford Univ. Press PY - 2003 SN - 0829-318X ER - TY - JOUR AB - Glutathione S-transferases (GST) detoxify many electrophilic xenobiotics, including several volatile organic compounds and pesticides. The GST activity for the conjugation of several xenobiotic substances was isolated from needles of Norway spruce (Picea abies L. Karst.) trees from a forest decline stand in the northern alps. Trees that exhibited different degrees of damage were selected from several stands in an altitude profile. The GST activity toward 1-chloro-2,4-dinitrobenzene (CDNB) in crude protein extracts of needles showed a seasonal pattern with highest activity during summer. The GST activity exhibited a strong dependence on the altitude of the stand showing highest activities in trees growing in the valley and lowest activities in trees growing in the summit regions of the mountain. When cytosolic GST from needles of healthy and damaged trees was purified, trees of healthy appearance exhibited three distinct GST isozymes with activities for the conjugation of CDNB and 1,2-dichloro-4-nitrobenzene (DCNB), whereas severely defoliated trees exhibited four GSTs with additional activity for the conjugation of ethacrynic acid. The main GST isozymes catalyzing the conjugation of CDNB differed in molecular weight, isoelectric point and catalytic properties between damaged and healthy trees. AU - Schröder, P. AU - Wolf, A.E.* C1 - 23299 C2 - 31189 SP - 503-508 TI - Characterization of glutathione S-transferases in needles of Norway spruce trees from a forest decline stand. JO - Tree Physiol. VL - 16 IS - 5 PB - Oxford Univ. Press PY - 1996 SN - 0829-318X ER -