Seco R, Peñuelas J, Filella I, Llusià J, Molowny-Horas R (2012). Els COVs al Montseny: entre l'smog urbà i la biogeneració. UABdivulga 03/2012.
Peñuelas J, Filella I, Estiarte M, Ogaya R, Llusià J, Sardans J, Jump A, Carnicer J, Rico L, Garbulsky M, Coll M, Díaz de Quijano M, Seco R, Rivas-Ubach A, Kefauver S, Barbeta A, Achoategui A, Mejía-Chang M, Gallardo A, Farre G, Fernández M, Terradas J (2012) Ecosystemic and biospheric interactions with carbon cycle. In Carbon dioxide budget: processes and tendencies symposium. Universitat Politècnica de Catalunya, May 23-25.
Llusia J., Llorens L., Bernal M., Verdaguer D., Peñuelas J. (2012) Effects of UV radiation and water limitation on the volatile terpene emission rates, photosynthesis rates, and stomatal conductance in four Mediterranean species. Acta Physiologiae Plantarum. 34: 757-769.LinkDoi: 10.1007/s11738-011-0876-8
This study examined the effects of the combination of UV radiation and water limitation on the leaf photosynthesis, stomatal conductance, and terpene emissions of four Mediterranean species. 1-year-old seedlings of these Mediterranean species [Daphne gnidium L., Pistacia lentiscus L., Ilex aquifolium L. and Laurus nobilis L.] were grown under one of three UV treatments (without UV, with UVA, or with UVA + UVB) and two watering regimes (high and low water supply). In general, UV treatments did not affect significantly leaf photosynthesis or stomatal conductance, although UVA and UVB radiation in September led to a reduction in leaf stomatal conductance in D. gnidium. Leaf photosynthesis rates did not differ significantly between the two watering treatments, even though, in three of the species, leaf stomatal conductance was significantly higher among the well-watered plants. The effects of UV on terpene emissions were species-specific; D. gnidium had the highest terpene emission rates when grown under UVA + UVB radiation, which was also true for L. nobilis in September. Overall, UV treatments did not have a significant effect on total terpene emission rates in I. aquifolium, but UVB and UVA in July and September, respectively, reduced emission rates in P. lentiscus. A limited water supply reduced the terpene emission rates in D. gnidium, increased emissions in L. nobilis, and did not affect the emission rates in the other two species. © 2011 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.
Llusia J., Peñuelas J., Seco R., Filella I. (2012) Seasonal changes in the daily emission rates of terpenes by Quercus ilex and the atmospheric concentrations of terpenes in the natural park of Montseny, NE Spain. Journal of Atmospheric Chemistry. 69: 215-230.LinkDoi: 10.1007/s10874-012-9238-1
We studied the daily patterns in the rates of terpene emissions by the montane holm oak, Quercus ilex, in three typical days of winter and three typical days of summer in Montseny, a natural park near Barcelona, and related them to the air concentrations of terpenes, ozone and NO 2. Terpene emission rates were about 10 times higher in summer than in winter. Emissions virtually stopped in the dark. In both seasons, rates of terpene emissions were well correlated with light, air temperature and relative humidity. Rates of emissions were also correlated with stomatal conductance and the rates of transpiration and photosynthesis. Almost all the individual terpenes identified followed the same pattern as total terpenes. The most abundant terpene was α-pinene, followed by sabinene + β-pinene, limonene, myrcene, camphene and α-phellandrene. Atmospheric terpene concentrations were also about 10 times higher in summer than in winter. A significant diurnal pattern with maxima at midday was observed, especially in summer. The increase by one order of magnitude in the concentrations of these volatile isoprenoids highlights the importance of local biogenic summer emissions in these Mediterranean forested areas which also receive polluted air masses from nearby or distant anthropic sources. Atmospheric concentrations of O 3 and NO 2 were also significantly higher in summer and at midday hours. In both seasons, concentrations of O 3 were significantly correlated with concentrations of terpenes and NO 2 in the air and with rates of terpene emission. © Springer Science+Business Media B.V. 2012.
Nogués I., Peñuelas J., Llusià J., Estiarte M., Munné-Bosch S., Sardans J., Loreto F. (2012) Physiological and antioxidant responses of Erica multiflora to drought and warming through different seasons. Plant Ecology. 213: 649-661.LinkDoi: 10.1007/s11258-012-0029-1
Climate change projections forecast a warming and an associated change in the distribution and intensity of rainfalls. In the case of the Mediterranean area, this will be reflected in more frequent and severe drought periods in the future. Within a long-term (9 years) manipulation experiment, we aimed to study the effect of the soil drought (15-20% decreased soil moisture) and warming conditions (+1°C warming) projected for the next decades onto photosynthetic rates and water relations, and onto the antioxidant and anti-stress defense capacity of Erica multiflora, a common species of the dry Mediterranean coastal scrublands, in two different seasons, spring and summer. Results indicated that none of the applied treatments was severe enough to induce a pronounced negative response of photosynthesis in this species well adapted to harsh Mediterranean conditions, but also highlighted important seasonal differences. Photosynthesis was limited by photoinhibition in spring and by stomatal closure in summer. Isoprenoid emission and the level of enzymatic and non-enzymatic antioxidants were lower in summer than in spring, whereas pigment and total phenolic contents were generally higher in summer. Volatile isoprenoid emissions were largely inhibited by drought and were not stimulated by warming. Drought and warming increased the oxidation state of ascorbate and reduced total glutathione levels in spring, but not in summer. It is concluded that E. multiflora plants can adapt to prolonged drought and warming, at least at the level simulated by our manipulative experiment, through changes in the seasonal physiological and antioxidant response of leaves. © 2012 Springer Science+Business Media B.V.
Filella I., Bosch J., Llusià J., Peñuelas A., Peñuelas J. (2011) Chemical cues involved in the attraction of the oligolectic bee Hoplitis adunca to its host plant Echium vulgare. Biochemical Systematics and Ecology. 39: 498-508.LinkDoi: 10.1016/j.bse.2011.07.008
Host recognition is a key process in oligolectic bees but the mechanisms through which they find and recognize appropriate pollen host plant are not entirely clear. Hoplitis adunca is a monolectic bee collecting pollen only from Echium spp. (Boraginaceae). We aimed to test whether Echium vulgare floral scent plays a major role in the attraction of H. adunca females, and to identify components of E. vulgare scent that may be involved in this specific attraction. We used a combination of behavioral and chemical (GC/GC-MS, PTR-MS) analyses. In order to identify the chemical cues likely to be involved in the specific attraction of H. adunca, we compared the scent of fresh flowers, nectar, pollen, and whole plants of E. vulgare and Anchusa officinalis, another Boraginaceae, which does not attract H. adunca. H. adunca females were attracted to the scent of E. vulgare flowers when offered against a blank or against the scent of A. officinalis flowers. However, H. adunca females were not attracted to the scent of A. officinalis flowers when offered against a blank. The emission spectra of the two plant species differed markedly, as did the emission spectra of various flower components (pollen, nectar and whole flowers) within a species. Pollen presented a low volatile release, but emitted significantly higher amounts of mass 55 (butanal, 1,3-butadiene, or other volatiles of molecular mass 54), and mass 83 (hexanal, hexenols, hexenyl acetate, or other volatiles of molecular mass 82) in E. vulgare than in A. officinalis. Nectar produced a particular emission spectrum with high emission rates of masses 109 and 123. Mass 109 may likely correspond to 1,4-benzoquinone, a volatile specifically measured in E. vulgare in parallel studies to this one. The flower emission spectrum was mainly a combination of the pollen and the nectar scents, although it also contained additional volatile compounds such as those of mass 63 or mass 81. As for terpenes, E. vulgare emitted limonene, longicyclene, junipene, trans-caryophyllene and α-humulene, that were not detected in A. officinalis, and the most emitted monoterpenes were α-pinene, junipene and limonene whereas the most emitted terpenoid by A. officinalis was α-pinene. After identifying these chemical cues, olfactory/behavioural assays with specific volatiles and combinations of volatiles are necessary to understand the chemical interactions of the H. adunca-E. vulgare system. © 2011 Elsevier Ltd.
Filella I., Bosch J., Llusiá J., Seco R., Peñuelas J. (2011) The role of frass and cocoon volatiles in host location by monodontomerus aeneus, a parasitoid of megachilid solitary bees. Environmental Entomology. 40: 126-131.LinkDoi: 10.1603/EN10165
Monodontomerus aeneus (Fonscolombe) is a parasitic wasp that oviposits on the prepupae and pupae of Osmia cornuta (Latreille) and other solitary bee species. A two-armed olfactometer was used to test the olfactory attractiveness of O. cornuta prepupae, cocoon, and larval frass to female M. aeneus. Both cocoon and frass attracted the female parasitoids, but frass alone was more attractive than the cocoon and the cocoon with frass was more attractive than frass alone. Female parasitoids were not attracted by the host prepupa. M33 (methanol) was the organic volatile most emitted by cocoons and m61 (acetic acid) was the compound most emitted by frass. However, cocoons showed higher emission for almost all compounds, including m61 (acetic acid). Although acetic acid alone attracted M. aeneus, a complex volatile signal is probably involved in the attraction process because the ratio of acetic acid and acetaldehyde characteristic of the frass was more attractive than other ratios. © 2011 Entomological Society of America.
Llusià J, Peñuelas J, Llorens L (2011) Responses to low increase in UV radiation on Volatile terpene emission rates, photosynthetic rates and Stomatal conductance in four Mediterranean species. Acta Physiologiae Plantarum doi: 10.1007/s11738-011-0876-8.
Blanc JS, Llusià J, Niinemets Ü, Noe SM, Peñuelas J (2011) Instantaneous and historical temperature effects on a-pinene emissions in Pinus halepensis and Quercus ilex. Journal of Environmental Biology 32: 1-6.
Sardans J, Peñuelas J, Estiarte M, Ogaya R, Llusià J (2011) The world's largest database on wild plants is published. UABdivulga 09/2011.
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