The capacity for thermal protection of photosynthetic electron transport varies for different monoterpenes in Quercus ilex

Copolovici L.O., Filella I., Llusià J., Niinemets Ü., Peñuelas J. (2005) The capacity for thermal protection of photosynthetic electron transport varies for different monoterpenes in Quercus ilex. Plant Physiology. 139: 485-496.
Enllaç
Doi: 10.1104/pp.105.065995

Resum:

Heat stress resistance of foliar photosynthetic apparatus was investigated in the Mediterranean monoterpene-emitting ever green sclerophyll species Quercus ilex. Leaf feeding with fosmidomycin, which is a specific inhibitor of the chloroplastic isoprenoid synthesis pathway, essentially stopped monoterpene emission and resulted in the decrease of the optimum temperature of photosynthetic electron transport from approximately 38°C to approximately 30°C. The heat stress resistance was partly restored by fumigation with 4 to 5 nmol mol1 air concentrations of monoterpene α-pinene but not with fumigations with monoterpene alcohol α-terpineol. Analyses of monoterpene physicochemical characteristics demonstrated that α-pinene was primarily distributed to leaf gas and lipid phases, while α-terpineol was primarily distributed to leaf aqueous phase. Thus, for a common monoterpene uptake rate, α-terpineol is less efficient in stabilizing membrane liquid-crystalline structure and as an antioxidant in plant membranes. Furthermore, α-terpineol uptake rate (U) strongly decreased with increasing temperature, while the uptake rates of α-pinene increased with increasing temperature, providing a further explanation of the lower efficiency of thermal protection by α-terpineol. The temperature-dependent decrease of α-terpineol uptake was both due to decreases in stomatal conductance,gw, and increased volatility of α-terpineol at higher temperature that decreased the monoterpene diffusion gradient between the ambient air (FA) and leaf (FI; U = gW[F A - FI]). Model analyses suggested that α-pinene reacted within the leaf at higher temperatures, possibly within the lipid phase, thereby avoiding the decrease in diffusion gradient, FA - F I. Thus, these data contribute to the hypothesis of the antioxidative protection of leaf membranes during heat stress by monoterpenes. These data further suggest that fumigation with the relatively low atmospheric concentrations of monoterpenes that are occasionally observed during warm windless days in the Mediterranean canopies may significantLy improve the heat tolerance of nonemitting vegetation that grows intermixed with emitting species. © 2005 American Society of Plant Biologists.

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Using plant biomonitors and flux modelling to develop O 3 dose-response relationships in Catalonia

Filella I., Peñuelas J., Ribas A. (2005) Using plant biomonitors and flux modelling to develop O 3 dose-response relationships in Catalonia. Environmental Pollution. 134: 145-151.
Enllaç
Doi: 10.1016/j.envpol.2004.07.007

Resum:

We used tobacco Bel-W3 biomonitoring data and ozone flux modelling (WINDEP model) with the aim of developing the absorbed dose-response relationship, and comparing this approach with the most commonly used AOT40 (the sum of hourly ozone concentrations above a cut-off of 40 ppb during daylight hours, when global radiation exceeds 50 W m -2) in the estimation of exposure-damage curves. Leaf damage values were more related to OAD 15 days, potential (potential ozone absorbed dose calculated over 15 consecutive days) than to AOT40 in all the studied stations. An OAD 15 days, potential of 180 mg m -2 was found to be the threshold for damage to the most sensitive species in this region under well watered conditions. The results show the applicability of the flux approach for risk assessment at the local scale, the improvement of the ozone damage estimation when the potential absorbed dose is modelled and used instead of just the ozone exposure, and finally, the possibilities opened by the use of biomonitoring networks. Modelling of biomonitors ozone absorbed dose improves damage estimation in comparison with exposure indices such as AOT40. © 2004 Elsevier Ltd. All rights reserved.

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Application of jasmonic acid enhances the emissions of monoterpenes and methyl salicylate and decreases the uptake of formaldehyde by Quercus ilex.

Filella I, Peñuelas J, Llusià J (2005) Application of jasmonic acid enhances the emissions of monoterpenes and methyl salicylate and decreases the uptake of formaldehyde by Quercus ilex. Geophysical Research Abstracts Vol. 7, 05456 (p).

Caterpillar-feeding induces large increases in foliar emissions of methanol, LOX volatiles and monoterpenes by Succisa pratensis.

Peñuelas J, Filella I, Stefanescu C, Llusià J (2005) Caterpillar-feeding induces large increases in foliar emissions of methanol, LOX volatiles and monoterpenes by Succisa pratensis. Geophysical Research Abstracts, Vol. 7, 05404 (p).

Sistemes naturals: Ecosistemes terrestres. A: J.E. Llebot ed., Informe sobre el canvi climàtic a Catalunya.

Peñuelas J, Filella I, Sabaté S, Gracia C (2005) Sistemes naturals: Ecosistemes terrestres. A: J.E. Llebot ed., Informe sobre el canvi climàtic a Catalunya. Institut Estudis Catalans, Barcelona, pp. 517-553.

Caterpillars of Euphydryas aurinia (Lepidoptera: Nymphalidae) feeding on Succisa pratensis leaves induce large foliar emissions of methanol

Peñuelas J., Filella I., Stefanescu C., Llusià J. (2005) Caterpillars of Euphydryas aurinia (Lepidoptera: Nymphalidae) feeding on Succisa pratensis leaves induce large foliar emissions of methanol. New Phytologist. 167: 851-857.
Enllaç
Doi: 10.1111/j.1469-8137.2005.01459.x

Resum:

• A major new discovery made in the last decade is that plants commonly emit large amounts and varieties of volatiles after damage inflicted by herbivores, and not merely from the site of injury. However, analytical methods for measuring herbivore-induced volatiles do not usually monitor the whole range of these compounds and are complicated by the transient nature of their formation and by their chemical instability. • Here we present the results of using a fast and highly sensitive proton transfer reaction-mass spectrometry (PTR-MS) technique that allows simultaneous on-line monitoring of leaf volatiles in the pptv (pmol mol-1) range. • The resulting on-line mass scans revealed that Euphydryas aurinia caterpillars feeding on Succisa pratensis leaves induced emissions of huge amounts of methanol - a biogeochemically active compound and a significant component of the volatile organic carbon found in the atmosphere - and other immediate, late and systemic volatile blends (including monoterpenes, sesquiterpenes and lipoxygenase-derived volatile compounds). • In addition to influencing neighboring plants, as well as herbivores and their predators and parasitoids, these large emissions might affect atmospheric chemistry and physics if they are found to be generalized in other plant species. © New Phytologist (2005).

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Butterflies highlight the conservation value of hay meadows highly threatened by land-use changes in a protected Mediterranean area

Stefanescu C., Peñuelas J., Filella I. (2005) Butterflies highlight the conservation value of hay meadows highly threatened by land-use changes in a protected Mediterranean area. Biological Conservation. 126: 234-246.
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Doi: 10.1016/j.biocon.2005.05.010

Resum:

Butterfly assemblages were used to characterize and evaluate the conservation value of the main habitat types in the Aiguamolls de l'Empordà Natural Park (north-eastern Spain), an important protected wetland area on the Mediterranean coast. Butterfly data were obtained from a number of transects walked as part of the Catalan Butterfly Monitoring Scheme, which uses a standardized methodology for monitoring butterflies. A Mantel test indicated a strong association between habitat types and the composition of butterfly assemblages and a principal component analysis ordinated individual butterfly species along a gradient from woodland to open areas, thereby indicating various degrees of shade tolerance. In addition, cluster analysis distinguished two main groups of habitats based on the similarities of their butterfly fauna: woodland and bramble clumps and a group of three different kinds of grasslands (traditionally hay meadows, pastures, and alfalfa fields). Hay meadows flooded in winter (the so-called closes) appeared always as the highest ranked habitat in terms of conservation evaluation: they have more butterflies and a slight tendency to harbor more and generally rarer species. This conclusion coincides with that of previous investigations that have indicated that the most diverse and rare plant communities in the whole Natural Park are present in the closes, and highlights the importance of traditionally managed hay meadows for wildlife. However, these hay meadows - one of the rarest habitats in the Mediterranean region - are in alarming decline and have become the most threatened habitat in this protected area: no longer profitable, we believe that the future of the closes will depend ultimately on the existence of agri-environmental schemes. © 2005 Elsevier Ltd. All rights reserved.

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