24 research outputs found
Terpenoid emissions of two mediterranean woody species in response to drought stress
Drought is a major environmental constrain affecting plant performance and survival,
particularly in Mediterranean ecosystems. Terpenoids may play a protective role under
these conditions, however, observations of drought effects on plant terpenoid emissions
are controversial ranging from decreased emissions to unaffected or increased release
of terpenoids. In the present study we investigated terpenoid emissions of cork
oak (Quercus suber) and gum rockrose (Cistus ladanifer) in response to summer
drought stress in 2017. Pre-dawn leaf water potential (9PD) decreased from 0.64
to 1.72 MPa in Q. suber and from 1.69 to 4.05 MPa in C. ladanifer, indicating
a transition from mild to severe drought along summer. Total terpenoid emissions
decreased with drought, but differed significantly between species (p < 0.001) and
in response to 9PD, air temperature and assimilation rates. C. ladanifer emitted a
large variety of >75 compounds comprising monoterpenes, sesquiterpenes and even
diterpenes, which strongly decreased from 1.37 0.23 mg g1 h1 to 0.40 0.08 mg
g1 h1 (p < 0.001) in response to drought. Total emission rates were positively
correlated to air temperature (p < 0.001). C. ladanifer behavior points toward terpenoid
leaf storage depletion and reduced substrate availability for terpenoid synthesis with
increasing drought, most likely accelerated by high air temperatures. Q. suber emitted
mainly monoterpenes and emissions declined significantly from June (0.50 0.08 mg
g1 h1) to August (0.29 0.02 mg g1 h1) (p < 0.01). Emission rates were weakly
correlated with net assimilation rates (R2 = 0.19, p < 0.001), but did not respond strongly
to 9PD and air temperature. Early onset of drought in 2017 most likely reduced plant
metabolism in Q. suber, resulting in diminished, but stable terpenoid fluxes. Calculation
of standard emission factors (at 30 C) revealed contrasting emission patterns of
decreasing, unaffected, or increasing fluxes of single terpenoid compounds. Unaffected
or drought-enhanced emissions of compounds such as a-pinene, camphene or manoyl
oxide may point toward a specific role of these terpenoids in abiotic stress adaptation.
In conclusion, these results suggest a strong negative, but species- and compoundspecific
effect of severe drought on terpenoid fluxes in Mediterranean ecosystemsinfo:eu-repo/semantics/publishedVersio
Volatile diterpene emission by two Mediterranean Cistaceae shrubs
Mediterranean vegetation emits a wide range of biogenic volatile organic compounds (BVOCs) among
which isoprenoids present quantitatively the most important compound class. Here, we investigated
the isoprenoid emission from two Mediterranean Cistaceae shrubs, Halimium halimifolium and Cistus
ladanifer, under controlled and natural conditions, respectively. For the first time, diurnal emission
patterns of the diterpene kaurene were detected in real-time by Proton-Transfer-Reaction-Timeof-
Flight-Mass-Spectrometer. Kaurene emissions were strongly variable among H. halimifolium
plants, ranging from 0.01 ± 0.003 to 0.06 ± 0.01 nmol mâ2 sâ1 in low and high emitting individuals,
respectively. They were in the same order of magnitude as monoterpene (0.01 ± 0.01 to 0.11 ± 0.04
nmol mâ2 sâ1) and sesquiterpene (0.01 ± 0.01 to 0.52 nmol mâ2 sâ1) emission rates. Comparable
range and variability was found for C. ladanifer under natural conditions. Labelling with 13C-pyruvate
suggested that emitted kaurene was not derived from de novo biosynthesis. The high kaurene content
in leaves, the weak relationship with ecophysiological parameters and the tendency of higher emissions
with increasing temperatures in the field indicate an emission from storage pools. This study highlights
significant emissions of kaurene from two Mediterranean shrub species, indicating that the release of
diterpenes into the atmosphere should probably deserve more attention in the futureinfo:eu-repo/semantics/publishedVersio
Distribution of Corbicula fluminea (MĂŒller, 1774) in the invaded range: a geographic approach with notes on species traits variability
Corbicula fluminea is considered one of the
most important non-native invasive species (NIS) in
aquatic systems mainly due to its widespread distribution
and ecological and economic impacts. This species
is known to negatively affect native bivalves, also with
severe effects on biodiversity and ecosystem functioning.
Throughout an exhaustive bibliographic survey and
with the aid of Geographic Information Systems tools,
this study tracks the species dispersion from its native
range, including the description of important physical
and environmental barriers. Additional analyses were
conducted to examine possible influences of latitudinal/
temperature gradients on important traits (e.g. life span,
maximum and mean body length, growth at the end of
first year). Altitude and winter minimum temperature
appear to be delaying the invasion worldwide, but it
seems inevitable that the species will spread across the
globe. Latitude and summer temperature show a
relationship with growth and life span. Overall, the
information gathered in this review may be relevant to
forecast future distribution patterns of this NIS, and to
anticipate the possible implementation of effective
management measures. Moreover, it may constitute a
valuabletool inthe prediction of population responses to
an increasingly changing environment.This research was supported by FCT
(Portuguese Foundation for Science and Technology), through
a PhD grant attributed to D. Crespo (SFRH/BD/80252/2011), a
post-doc grant attributed to S. Leston (SFRH/BPD/91828/2012)
and M Dolbeth (SFRH/BPD/41117/2007) and BIOCHANGED
project (PTDC/MAR/111901/2009), subsidized by the
European Social Fund and MCTES (MinistĂ©rio da CiĂȘncia,
Tecnologia e Ensino Superior) National Funds, through the
POPH (Human Potential Operational Programme), QREN
(National Strategic Reference Framework) and COMPETE
(Programa Operacional Factores de Competitividade).info:eu-repo/semantics/publishedVersio
Plant-specific volatile organic compound emission rates from young and mature leaves of Mediterranean vegetation
International audienc
Root anoxia effects on physiology and emissions of volatile organic compounds (VOC) under short- and long-term inundation of trees from Amazonian floodplains
Volatile organic compound (VOC) emissions are affected by a variety of biotic and abiotic factors such as light intensity, temperature, CO2 and drought. Another stress factor, usually overlooked but very important for the Amazon region, is flooding. We studied the exchange of VOCs in relation to CO2 exchange and transpiration of 8 common tree species from the Amazonian floodplain forest grown up from seeds using a dynamic enclosure system. Analysis of volatile organics was performed by PTR-MS fast online measurements. Our study confirmed emissions of ethanol and acetaldehyde at the beginning of root anoxia after inundation, especially in less anoxia adapted species such as Vatairea guianensis, but not for Hevea spruceana probably due to a better adapted metabolism. In contrast to short-term inundation, long-term flooding of the root system did not result in any emission of ethanol or/and acetaldehyde. Emission of other VOCs, such as isoprenoids, acetone, and methanol exhibited distinct behavior related to the origin (igapó or vårzea type of floodplain) of the tree species. Also physiological activities exhibited different response patterns for trees from igapó or vårzea. In general, isoprenoid emissions increased within the course of some days of short-term flooding. After a long period of waterlogging, VOC emissions decreased considerably, along with photosynthesis, transpiration and stomatal conductance. However, even under long-term testing conditions, two tree species did not show any significant decrease or increase in photosynthesis. In order to understand ecophysiological advantages of the different responses we need field investigations with adult tree species. © 2012 Bracho-Nunez et al.; licensee Springer
Differential accumulation of volatile organic compounds by leaves and roots of two guianese philodendron species, P.fragrantissimum kunth and P.melinonii brongn
Leaf and root essential oils of two closely related but ecologically distant Philodendron species were extracted in natural conditions in French Guiana and analysed by GC/MS to i) describe the blends of volatile organic compounds (VOCs) produced by those species and ii) analyse species and environment-based variations in extracts composition. A total of 135 VOCs were detected with a majority of aliphatic sesquiterpenes. P.fragrantissimum produced mainly -bisabolene (on average 29.12% of the extract) as well as - and -selinene (14.52% and 17.50%, respectively) while in P.melinonii, four aliphatic sesquiterpenes could alternatively be the main component: (E)--farnesene (up to 91.42% of the extract), germacrene-D (73.74%), -caryophyllene (51.63%) and trans--bergamotene (41.26%). A significant effect of species and organs on extracts composition was observed while the environment (sun exposure) only affected the relative proportions of monoterpenes and sesquiterpenes in roots of P.melinonii. These results are discussed in the light of the potential role of leaf and root terpenes in Philodendron species