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Josep Peñuelas - One of the best experts on this subject based on the ideXlab platform.
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Increasing carbon discrimination rates and depth of water uptake favor the growth of Mediterranean evergreen trees in the ecotone with temperate deciduous forests
Global Change Biology, 2017Co-Authors: Adrià Barbeta, Josep PeñuelasAbstract:Tree populations at the low-altitudinal or -latitudinal limits of species' distributional ranges are predicted to retreat toward higher altitudes and latitudes to track the ongoing changes in climate. Studies have focused on the climatic sensitivity of the retreating species, whereas little is known about the potential replacements. Competition between tree species in forest ecotones will likely be strongly influenced by the ecophysiological responses to heat and drought. We used tree-ring widths and δ13 C and δ18 O chronologies to compare the growth rates and long-term ecophysiological responses to climate in the temperate-Mediterranean ecotone formed by the deciduous Fagus sylvatica and the evergreen Quercus Ilex at the low altitudinal and southern latitudinal limit of F. sylvatica (NE Iberian Peninsula). F. sylvatica growth rates were similar to those of other southern populations and were surprisingly not higher than those of Q. Ilex, which were an order of magnitude higher than those in nearby drier sites. Higher Q. Ilex growth rates were associated with high temperatures, which have increased carbon discrimination rates in the last 25 years. In contrast, stomatal regulation in F. sylvatica was proportional to the increase in atmospheric CO2 . Tree-ring δ18 O for both species were mostly correlated with δ18 O in the source water. In contrast to many previous studies, relative humidity was not negatively correlated with tree-ring δ18 O but had a positive effect on Q. Ilex tree-ring δ18 O. Furthermore, tree-ring δ18 O decreased in Q. Ilex over time. The sensitivity of Q. Ilex to climate likely reflects the uptake of deep water that allowed it to benefit from the effect of CO2 fertilization, in contrast to the water-limited F. sylvatica. Consequently, Q. Ilex is a strong competitor at sites currently dominated by F. sylvatica and could be favored by increasingly warmer conditions.
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dampening effects of long term experimental drought on growth and mortality rates of a holm oak forest
Global Change Biology, 2013Co-Authors: Adrià Barbeta, Roma Ogaya, Josep PeñuelasAbstract:Forests respond to increasing intensities and frequencies of drought by reducing growth and with higher tree mortality rates. Little is known, however, about the long-term consequences of generally drier conditions and more frequent extreme droughts. A Holm oak forest was exposed to experimental rainfall manipulation for 13 years to study the effect of increasing drought on growth and mortality of the dominant species Quercus Ilex, Phillyrea latifolia, and Arbutus unedo. The drought treatment reduced stem growth of A. unedo (� 66.5%) and Q. Ilex (� 17.5%), whereas P. latifolia remained unaffected. Higher stem mortality rates were noticeable in Q. Ilex (+42.3%), but not in the other two species. Stem growth was a function of the drought index of early spring in the three species. Stem mortality rates depended on the drought index of winter and spring for Q. Ilex and in spring and summer for P. latifolia, but showed no relation to climate in A. unedo. Following a long and intense drought (2005–2006), stem growth of Q. Ilex and P. latifolia increased, whereas it decreased in A. unedo. Q. Ilex also enhanced its survival after this period. Furthermore, the effect of drought treatment on stem growth in Q. Ilex and A. unedo was attenuated as the study progressed. These results highlight the different vulnerabilities of Mediterranean species to more frequent and intense droughts, which may lead to partial species substitution and changes in forest structure and thus in carbon uptake. The response to drought, however, changed over time. Decreased intra- and interspecific competition after extreme events with high mortality, together with probable morphological and physiological acclimation to drought during the study period, may, at least in the short term, buffer forests against drier conditions. The long-term effects of drought consequently deserve more attention, because the ecosystemic responses are unlikely to be stable over time.Nontechnical summaryIn this study, we evaluate the effect of long-term (13 years) experimental drought on growth and mortality rates of three forest Mediterranean species, and their response to the different intensities and durations of natural drought. We provide evidence for species-specific responses to drought, what may eventually lead to a partial community shift favoring the more drought-resistant species. However, we also report a dampening of the treatment effect on the two drought-sensitive species, which may indicate a potential adaptation to drier conditions at the ecosystem or population level. These results are thus relevant to account for the stabilizing processes that would alter the initial response of ecosystem to drought through changes in plant physiology, morphology, and demography compensation.
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drought warming and soil fertilization effects on leaf volatile terpene concentrations in pinus halepensis and quercus Ilex
Acta Physiologiae Plantarum, 2009Co-Authors: Josepsalvador Blanch, Josep Peñuelas, Jordi Sardans, Joan LlusiaAbstract:The changes in foliar concentrations of volatile terpenes in response to water stress, fertilization and tem- perature were analyzed in Pinus halepensis and Quercus Ilex. The most abundant terpenes found in both species were a-pinene and D 3 -carene. b-Pinene and myrcene were also abundant in both species. P. halepensis concentrations were much greater than those of Q. Ilex in agreement with the lack of storage in the latter species (15205.60 ± 1140.04 vs. 0.54 ± 0.08 l gg -1 (d.m.)). The drought treatment (reduction to 1/3 of full watering) significantly increased the total terpene concentrations in both species (54% in P. halepensis and 119% in Q. Ilex). The fertil- ization treatment (addition of either 250 kg N ha -1 or 250 kg P ha -1 or both) had no significant effects on ter- pene foliar concentrations. The terpene concentrations increased from 0.25 l gg -1 (d.m.) at 30C to 0.70 l gg -1 (d.m.) at 40 Ci nQ. Ilex (the non-storing species) and from 2,240 l gg -1 (d.m.) at 30C to 15,621 l gg -1 (d.m.) at 40 Ci nP. halepensis (the storing species). Both species presented negative relationship between terpene concen- trations and relative water contents (RWC). The results of this study show that higher terpene concentrations can be expected in the warmer and drier conditions predicted for the next decades in the Mediterranean region.
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sensitivity of terpene emissions to drought and fertilization in terpene storing pinus halepensis and non storing quercus Ilex
Physiologia Plantarum, 2007Co-Authors: Josepsalvador Blanch, Josep Peñuelas, Joan LlusiaAbstract:We studied the effects of water stress, fertilization and time course on foliar volatile terpene emission rates by Quercus Ilex and Pinus halepensis in a garden experiment. The terpenes mostly emitted by both species were alpha-pinene, beta-pinene, beta-myrcene and Delta(3)-carene. P. halepensis emission rates (average 31.45 microg g(-1) DM h(-1)) were similar to those of Q. Ilex (average 31.71 microg g(-1) DM h(-1)). The effects of drought (reduction to one-third of full watering) and fertilization (250 kg N ha(-1), 250 kg P ha(-1), or both) were different depending on the species: the drought treatment significantly increased the terpene emissions from Q. Ilex by 33%, and the fertilization treatments reduced the terpene emissions from P. halepensis by 38%. Terpene emission rates increased with time course in parallel to raising summer temperatures in P. halepensis and Q. Ilex, whose emission rates were temperature related (r = 0.42 and r = 0.68, respectively) and light related (r = 0.32 and r = 0.57, respectively). There was a positive relationship for P. halepensis, and a negative relationship for Q. Ilex, between emission rates and relative water contents. No relationship was found between emission rates and N or P foliar concentrations. The results of this study show complex species-specific responses with stronger and faster short-term responses in terpene-non-storing than in storing species and indicate that terpene emissions may significantly change in the warmer, drier and more fertilized conditions predicted for the next decades in the Mediterranean region.
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Effects of winter cold stress on photosynthesis and photochemical efficiency of PSII of the Mediterranean Cistus albidus L. and Quercus Ilex L.
Plant Ecology, 2005Co-Authors: G. Oliveira, Josep PeñuelasAbstract:This study examined the photosynthetic and growth performances of potted plants of Cistus albidus L. and Quercus Ilex L. submitted either to natural Mediterranean winter conditions or to mild greenhouse conditions. Plants grown outdoors exhibited lower light and CO_2-saturated CO_2 assimilation rates (A_sat) and apparent quantum yield (Φ_i) than those indoors. Until mid-winter, C. albidus had higher A_sat than Q. Ilex , but differences disappeared after a period of severe cold. Maximal photochemical efficiency of PSII (Fv/Fm) measured predawn was higher in C. albidus than in Q. Ilex , and decreased throughout the season in outdoor plants. Fv/Fm also decreased at light saturation (A_sat) in both species. Fv/Fm was correlated with photosynthetic capacity and efficiency (quantum yield), but the resulting regression slopes were different between the two species. At the physiological level, C. albidus seemed to cope better with cold stress than Q. Ilex . However, winter stress induced reduction of leaf absorptance, increased leaf mass per area, extensive leaf damage and high plant mortality in C. albidus . This suggests that the high performance of C. albidus leaves is not likely to be maintained for long periods of cold stress, and may therefore depend on continuous leaf replacement. Quercus Ilex showed a conservative behaviour, with low net assimilation rates but greater leaf and plant survival than C. albidus .
Edward J. Kennelly - One of the best experts on this subject based on the ideXlab platform.
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lc ms metabolomics and chemotaxonomy of caffeine containing holly Ilex species and related taxa in the aquifoliaceae
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Adam Negrin, Chunlin Long, Timothy J. Motley, Edward J. KennellyAbstract:Ilex species have been consumed traditionally as medicinal teas worldwide. Though the presence of caffeine has been reported in several species, little is known about secondary-metabolite diversity within and among these taxa. Leaf samples of Ilex guayusa, Ilex paraguariensis, and Ilex vomitoria were analyzed by liquid chromatography-mass spectrometry and comparative metabolite profiling with Ilex cassine and other Ilex species to identify chemotaxonomic markers, delimit species, and provide an assessment of chemodiversity. Purine alkaloids were detected and quantified in I. guayusa, I. paraguariensis, and I. vomitoria. Reports of caffeine for I. cassine were not corroborated, suggesting that I. vomitoria was the traditional source of the Native North American tea yaupon. The tetramethyluric acid, theacrine, was detected for the first time in the genus Ilex as a low-level chemotaxonomic marker in I. vomitoria samples. Chemotaxonomy and metabolomics support a close relationship for caffeine-containing Ilex species.
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LC-MS Metabolomics and Chemotaxonomy of Caffeine-Containing Holly (Ilex) Species and Related Taxa in the Aquifoliaceae
2019Co-Authors: Adam Negrin, Chunlin Long, Timothy J. Motley, Edward J. KennellyAbstract:Ilex species have been consumed traditionally as medicinal teas worldwide. Though the presence of caffeine has been reported in several species, little is known about secondary-metabolite diversity within and among these taxa. Leaf samples of Ilex guayusa, Ilex paraguariensis, and Ilex vomitoria were analyzed by liquid chromatography–mass spectrometry and comparative metabolite profiling with Ilex cassine and other Ilex species to identify chemotaxonomic markers, delimit species, and provide an assessment of chemodiversity. Purine alkaloids were detected and quantified in I. guayusa, I. paraguariensis, and I. vomitoria. Reports of caffeine for I. cassine were not corroborated, suggesting that I. vomitoria was the traditional source of the Native North American tea yaupon. The tetramethyluric acid, theacrine, was detected for the first time in the genus Ilex as a low-level chemotaxonomic marker in I. vomitoria samples. Chemotaxonomy and metabolomics support a close relationship for caffeine-containing Ilex species
Victor Resco De Dios - One of the best experts on this subject based on the ideXlab platform.
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similar diurnal seasonal and annual rhythms in radial root expansion across two coexisting mediterranean oak species
Tree Physiology, 2020Co-Authors: Josu G Alday, Julio J Camarero, Jesus Revilla, Victor Resco De DiosAbstract:: Dendrometers are being increasingly used to measure stem-radius changes in trees and to unravel the mechanisms underlying stem daily rhythms of radial expansion and contraction. Nevertheless, automated dendrometers have not been often used to measure root-radius dynamics, their relationship with environmental variables, and the influence of endogenous processes, especially in drought-prone Mediterranean areas. Here, we measured root-radius dynamics of two coexisting oak species (the evergreen Quercus Ilex and the deciduous Quercus faginea). Our goals were to describe annual, seasonal and diurnal scale root-radius patterns, and, to disentangle the role of different environmental parameters as drivers. Long-term high-resolution measurements (every 15 minutes over 7 years) were collected with automated point dendrometers on the main tree roots of five individuals per species. Root-radius annual change patterns were bimodal and similar for both oak species. Q. faginea showed three times larger root increment in the spring than Q. Ilex, but the bimodal pattern was stronger in Q. Ilex which showed a larger root increment in autumn. Q. faginea showed an earlier root phenological activation in the spring and in late summer compared with Q. Ilex. The effects of environmental drivers across species were similar at daily scales: root-radius increased with air temperature and soil moisture and it decreased with rising vapor pressure deficit. Furthermore, daily root-radius variations for both oak species were maintained after extracting statistically the environmental effects, which points towards a significant role of endogenous drivers. These differences in root-radius change patterns at seasonal to daily scales likely result from the differences in leaf phenology and growth strategy. Q. faginea is deciduous and faster growing rate in spring than the evergreen Q. Ilex, which can grow more in summer.
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Similar diurnal, seasonal and annual rhythms in radial root expansion across two coexisting Mediterranean oak species.
Tree Physiology, 2020Co-Authors: Josu G Alday, Julio J Camarero, Jesus Revilla, Victor Resco De DiosAbstract:Dendrometers are being increasingly used to measure stem radius changes in trees and to unravel the mechanisms underlying stem daily rhythms of radial expansion and contraction. Nevertheless, automated dendrometers have not been often used to measure root radius dynamics, their relationship with environmental variables and the influence of endogenous processes, especially in drought-prone Mediterranean areas. Here, we measured root radius dynamics of two coexisting oak species (the evergreen Quercus Ilex L. and the deciduous Quercus faginea Lam). Our goals were to describe annual, seasonal and diurnal scale root radius patterns and to disentangle the role of different environmental parameters as drivers. Long-term high-resolution measurements (every 15 min over 7 years) were collected with automated point dendrometers on the main tree roots of five individuals per species. Root radius annual change patterns were bimodal and similar for both oak species. Quercus faginea Lam showed three times larger root increment in the spring than Q. Ilex, but the bimodal pattern was stronger in Q. Ilex, which showed a larger root increment in autumn. Quercus faginea Lam showed an earlier root phenological activation in the spring and in late summer compared with Q. Ilex. The effects of environmental drivers across species were similar at daily scales: root radius increased with air temperature and soil moisture, and it decreased with rising vapor pressure deficit. Furthermore, daily root radius variations for both oak species were maintained after extracting statistically the environmental effects, which points toward a significant role of endogenous drivers. These differences in root radius change patterns at seasonal to daily scales likely result from the differences in leaf phenology and growth strategy. Quercus faginea Lam is deciduous and has a faster growing rate in spring than the evergreen Q. Ilex, which can grow more in summer.
Claudia Anesini - One of the best experts on this subject based on the ideXlab platform.
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antifungal activity of the aqueous extract of Ilex paraguariensis against malassezia furfur
Phytotherapy Research, 2010Co-Authors: Rosana Filip, Roberto Davicino, Claudia AnesiniAbstract:Malassezia furfur is a lipodependent, dimorphic and saprophyte fungus which causes pityriasis versicolor, dandruff and seborrheic dermatitis in humans. The drugs available to treat this fungal infection are few. These drugs are highly toxic and are costly when used in prolonged treatments. For these reasons, it is necessary to find new compounds to treat these infections. Ilex paraguariensis St Hilaire is a plant that grows in Argentina, Brazil and Paraguay. The aim of this study was to evaluate the effect of the aqueous extract of Ilex paraguariensis on the growth of M. furfur. High performance liquid chromatography (HPLC) was employed to identify and isolate compounds of I. paraguariensis and the agar-well diffusion method was used to assess the antifungal activity of the extract. The fungicidal/fungistatic effect was evaluated by the modified Thompson assay. The results demonstrated that the aqueous extract of Ilex paraguariensis (1000 mg/ml) possesses inhibitory activity against M. furfur. This antimalassezial activity was equivalent to 2.7 μg/ml of ketoconazole. Therefore, the topical use of Ilex paraguariensis extract as alternative antifungal agent can be suggested. Copyright © 2009 John Wiley & Sons, Ltd.
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Antifungal activity of the aqueous extract of Ilex paraguariensis against Malassezia furfur.
Phytotherapy research : PTR, 2009Co-Authors: Rosana Filip, Roberto Davicino, Claudia AnesiniAbstract:Malassezia furfur is a lipodependent, dimorphic and saprophyte fungus which causes pityriasis versicolor, dandruff and seborrheic dermatitis in humans. The drugs available to treat this fungal infection are few. These drugs are highly toxic and are costly when used in prolonged treatments. For these reasons, it is necessary to find new compounds to treat these infections. Ilex paraguariensis St Hilaire is a plant that grows in Argentina, Brazil and Paraguay. The aim of this study was to evaluate the effect of the aqueous extract of Ilex paraguariensis on the growth of M. furfur. High performance liquid chromatography (HPLC) was employed to identify and isolate compounds of I. paraguariensis and the agar-well diffusion method was used to assess the antifungal activity of the extract. The fungicidal/fungistatic effect was evaluated by the modified Thompson assay. The results demonstrated that the aqueous extract of Ilex paraguariensis (1000 mg/ml) possesses inhibitory activity against M. furfur. This antimalassezial activity was equivalent to 2.7 microg/ml of ketoconazole. Therefore, the topical use of Ilex paraguariensis extract as alternative antifungal agent can be suggested.
Roselyne Lumaret - One of the best experts on this subject based on the ideXlab platform.
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phylogeographical variation of chloroplast dna in holm oak quercus Ilex l
Molecular Ecology, 2008Co-Authors: Roselyne Lumaret, Celine Mir, H Michaud, V RaynalAbstract:Variation in the lengths of restriction fragments (RFLPs) of the whole chloroplast DNA molecule was studied in 174 populations of Quercus Ilex L. sampled over the entire distribution of this evergreen and mainly Mediterranean oak species. By using five endonucleases, 323 distinct fragments were obtained. From the 29 and 17 cpDNA changes identified as site and length mutations, respectively, 25 distinct chlorotypes were distinguished, mapped and treated cladistically with a parsimony analysis, using as an outgroup Q. alnifolia Poech, a closely related evergreen oak species endemic to Cyprus where Q. Ilex does not grow. The predominant role of Q. Ilex as maternal parent in hybridization with other species was reflected by the occurrence of a single very specific lineage of related chlorotypes, the most ancestral and recent ones being located in the southeastern and in the northwestern parts of the species’ geographical distribution, respectively. The lineage was constituted of two clusters of chlorotypes observed in the ‘Ilex’ morphotyped populations of the Balkan and Italian Peninsulas (including the contiguous French Riviera), respectively. A third cluster was divided into two subclusters identified in the ‘rotundifolia’ morphotyped populations of North Africa, and of Iberia and the adjacent French regions, respectively. Postglacial colonization probably started from three distinct southerly refugia located in each of the three European peninsulas, and a contact area between the Italian and the Iberian migration routes was identified in the Rhone valley (France). Chlorotypes identical or related to those of the Iberian cluster were identified in the populations from Catalonia and the French Languedoc region, which showed intermediate morphotypes, and in the French Atlantic populations which possessed the ‘Ilex’ morphotype, suggesting the occurrence of adaptive morphological changes in the northern part of the species’ distribution.
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isoprenoid emissions of quercus spp q suber and q Ilex in mixed stands contrasting in interspecific genetic introgression
New Phytologist, 2004Co-Authors: Michael Staudt, Celine Mir, Richard Joffre, Serge Rambal, Aurelie Bonin, Damien Landais, Roselyne LumaretAbstract:Summary • Among oak species, Quercus Ilex is classified as a monoterpene emitter and Q. suber is mainly known as a nonisoprenoid emitter. The extent and origin of this diversification is unknown. • We examined intra- and interspecific emission variability in two mixed stands which differed in their level of hybridization and reciprocal genetic introgression based on variations in cytoplasmic (chloroplast DNA) and nuclear (allozyme) markers. • At both sites all trees identified as Q. Ilex, or as recent descendants from Q. Ilex × Q. suber hybrids, emitted monoterpenes. Of Q. suber trees (genetically introgressed or not by Q. Ilex), 91% were also monoterpene emitters, and the remainder nonemitters. One tree identified as a Q. canariensis × Q. Ilex hybrid emitted both isoprene and monoterpenes. Compared with Q. Ilex, the standard emission rate of Q. suber was higher in summer and lower in autumn. Both species emitted the same monoterpenes, proportions of which showed significant intra- and interspecific variability. • The results suggest that Q. suber populations in the French Mediterranean intrinsically emit monoterpenes, and that gene flow between oak species contributes to diversification of emission signatures.
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Allozyme characterisation of four Mediterranean evergreen oak species.
Biochemical Systematics and Ecology, 2001Co-Authors: Lamjed Toumi, Roselyne LumaretAbstract:Abstract Polymorphism at 11 enzyme loci was used to compare the four evergreen oak species of the Mediterranean Basin and to establish their taxonomical relationships. As a comparison, two evergreen oak species from Tibet, located in the primary distribution area of evergreen oaks, were analysed at the same loci. Cladistic analyses led to the separation of a cluster of four species, namely the three Mediterranean Q. Ilex, Q. coccifera and Q. alnifolia and the Tibetan Q. aquifolioides. The other Tibetan species, Q. semicarpifolia, and Q. suber, from the Western Mediterranean Basin, were very distinct genetically from the four other species. These results were not consistent with previous taxonomical treatment, based on morphology alone, which classified Q. Ilex and Q. coccifera in “Ilex group” (=subgenus Sclerophyllodrys O. Schwartz), and the other four species in “cerris group” (subgenus Cerris, according to Schwartz). Allozyme variation has thus provided useful information to clarify the taxonomy of evergreen oaks.
