Genetics, phosphorus availability, and herbivore-derived induction as sources of phenotypic variation of leaf volatile terpenes in a pine species

Oleoresin produced and stored in pine tree leaves provides direct resistance to herbivores, while leaf volatile terpenes (LVT) in the resin are also powerful airborne infochemicals. Resin concentration and profile show considerable spatial and temporal phenotypic variation within and among pine populations. LVT biochemistry is known to be under genetic control, and although LVT should be plastic to diverse abiotic and biotic environmental factors such as nutrient availability and herbivore attack, little is known about their relative contributions and interactive effects. The aim of this paper was to clarify whether reduced phosphorus availability could increase the LVT concentration and affect the expression of herbivore-derived induced defences, and how plasticity would contribute to the phenotypic variation of LVT. The constitutive and methyl-jasmonate (MeJa) induced LVT concentration and profile were analysed in 17 half-sib Pinus pinaster families growing under two levels of P-availability (complete and P-limited fertilization). Individual terpene concentrations showed large additive genetic variation, which was more pronounced in the control than in MeJa-induced pines. MeJa application did not affect the LVT concentration, but significantly modified the LVT profile by depleting the α-pinene content and reducing the sesquiterpene fraction. Low P-availability strongly reduced plant growth and foliar nutrient concentrations, but did not affect LVT concentration and profile, and did not interact with MeJa-induction. Results indicate a strong homeostasis of LVT concentration to P-availability, and minor changes in the LVT profile due to MeJa-induction. Genetic variation appears to be the main source of phenotypic variation affecting the LVT concentration in this pine species.This work was supported by the Spanish Instituto Nacional de Investigación y Tecnología Agraria y Agroalimentaria (grant number INIA-RTA07-100; and DOC-INIA and PREDOC-INIA fellows for LS and XM, respectively); the Spanish Agency of Science and Technology (grant numbers CGL2006-04025/BOS, CGL2010-17172, and CSD2008- 00040 for JP and JL; and AGL2010-18724 and PSE310000 for RZ and LS); and the Catalonian Government (grant number SGR 2009-1458).Peer reviewe

The handbook for standardized field and laboratory measurements in terrestrial climate change experiments and observational studies (ClimEx)

1. Climate change is a world‐wide threat to biodiversity and ecosystem structure, functioning and services. To understand the underlying drivers and mechanisms, and to predict the consequences for nature and people, we urgently need better understanding of the direction and magnitude of climate change impacts across the soil–plant–atmosphere continuum. An increasing number of climate change studies are creating new opportunities for meaningful and high‐quality generalizations and improved process understanding. However, significant challenges exist related to data availability and/or compatibility across studies, compromising opportunities for data re‐use, synthesis and upscaling. Many of these challenges relate to a lack of an established ‘best practice’ for measuring key impacts and responses. This restrains our current understanding of complex processes and mechanisms in terrestrial ecosystems related to climate change. 2. To overcome these challenges, we collected best‐practice methods emerging from major ecological research networks and experiments, as synthesized by 115 experts from across a wide range of scientific disciplines. Our handbook contains guidance on the selection of response variables for different purposes, protocols for standardized measurements of 66 such response variables and advice on data management. Specifically, we recommend a minimum subset of variables that should be collected in all climate change studies to allow data re‐use and synthesis, and give guidance on additional variables critical for different types of synthesis and upscaling. The goal of this community effort is to facilitate awareness of the importance and broader application of standardized methods to promote data re‐use, availability, compatibility and transparency. We envision improved research practices that will increase returns on investments in individual research projects, facilitate second‐order research outputs and create opportunities for collaboration across scientific communities. Ultimately, this should significantly improve the quality and impact of the science, which is required to fulfil society's needs in a changing world

Contrasting species-specific, compound-specific, seasonal, and interannual responses of foliar isoprenoid emissions to experimental drought in a mediterranean shrubland.

9 páginas, 4 tablas, 2 figuras.We aimed to test the effect of soil drought conditions projected by general circulation models and ecophysiological models for the next few decades on emission rates of isoprenoids by Mediterranean shrublands. We conducted a field experiment in which we generated soil drought (ca. 12%–20% decreased soil moisture) using automatically sliding curtains, and we measured foliar isoprenoid emissions in the three dominant species of the studied shrubland (Erica multiflora L., Globularia alypum L., and Pinus halepensis L.) in two different annual periods. Monoterpene emissions were detected in the three studied species, but isoprene emissions were significantly detected only in E. multiflora. Main volatile terpenes emitted by the three species were α‐pinene, β‐myrcene, limonene, and Δ3‐carene. In general, maximum isoprenoid emission rates were found in the hottest periods, and minimum emission rates were found in winter. Isoprene emissions in E. multiflora ranged between practically 0 μg g−1 (dry matter) h−1 in winter 2005 and 57 μg g−1 (dry matter) h−1 in summer 2003. Isoprene emissions were 75% lower during the dry second annual period, 2004–2005, than during the first year, 2003–2004. In E. multiflora, there was an overall decrease of 19% in isoprene emissions in response to soil drought. Conversely, monoterpene emissions increased by 26.4% in drought treatment. In G. alypum, there was an overall increase of 75% in terpene emissions in response to soil drought. In P. halepensis, drought treatment increased terpene emission rates by 156%. Drought treatment affected the emissions mainly in the hottest seasons, spring and summer. There were strong compound‐specific, species‐specific, interannual, and seasonal changes in the emission rates and in their response to the treatments. These data might help to improve prediction algorithms, inventories, and modeling of isoprenoid emissions and of their response to climate change (decreased isoprene emissions and increased monoterpene emissions under moderate or short‐term drought and decreased emissions under severe or long‐term drought), but the great variability highlights the difficulty of the task.Our research was partly supported by ISONET (Marie Curie network contract MC‐RTN‐CT‐2003 504720) from the European Union, grants CGL2004‐01402/BOS and CGL2006‐04025/BOS from the Spanish government, a 2004 grant from the Fundación BBVA, a European Union grant (ALARM contract 506675), and a SGR2005‐00312 grant from the Catalan government.Peer reviewe

Terpenoid emissions from Quercus robur. A case study of Galicia (NW Spain).

8 páginas, 3 tablas, 3 figuras.Isoprene and monoterpenes emission fluxes emitted by Quercus robur seedlings were measured at a leaf scale in the field. Isoprene emissions were always predominant over the monoterpene ones, a-pinene, b-pinene and camphene being the most abundant emitted monoterpenes. Emission fluxes were normalised at standard conditions of temperature and photosynthetically active radiation, PAR, (30 C and 1000 mmol m 2 s 1 respectively) using temperature and light dependent algorithms. The standardised emission fluxes ranged from 43 to 73 mg gDM 1 h 1 for isoprene and from 0.04 to 2.95 mg gDM 1 h 1 for the monoterpenes. The values reported in the literature are within our experimental intervals. These standardised fluxes were used to estimate the Quercus robur emissions in Galicia (NW Spain). This region is characterised by its abundant forest extensions where Quercus robur occupies the second place in species abundance with a total of 195029 ha of Quercus robur pure stands. To estimate the region emission fluxes, both the extension and distribution of the forest areas and the regional climatic conditions over five years (2002–2006) were taken into account. The averaged annual fluxes regarding the forest extension were 0.04 t ha 1 yr 1 for isoprene and 0.52 kg ha 1 yr 1 for monoterpenes. This means averaged annual fluxes of 9730 t yr 1 and 114 t yr 1 for isoprene and monoterpenes, respectively. These values place Galicia as an important isoprene emitter power in Spain as a consequence of the extension of its forests more than of the climatic conditionJP acknowledges funding from grants from the Catalan Government (SGR2005-00312), and the Spanish Ministry of Education and Science (CGL2006-04025/BOS and Consolider Montes CSD2008-00040).Peer reviewe

Sensivity of terpene emissions to drought and fertilization in terpene-storing Pinus halepensis and non-storing Quercus ilex.

15 páginas, 8 figuras, 3 tablas.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 α-pinene, β-pinene, β-myrcene and Δ3-carene. P. halepensis emission rates (average 31.45 μg g−1 DM h−1) were similar to those of Q. ilex (average 31.71 μg 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.Our research was partly supported by the European Union’s ecological and physiological functions of biogenic isoprenoids and their impact on the environment (ISONET) (Marie Curie network contract MC-RTN-CT-2003 504720), by grants CGL2004-01402/BOS and CGL2006-04025/BOS from the Spanish Government, by a 2004 grant from the Fundación Banco Bilbao Vizcaya Argentaria (BBVA), by the Catalan Government project (SGR2005/00312) and by the European Union project Assessing Large Scale Risks for Biodiversity with tested Methods (ALARM) (Contract 506675).Peer reviewe

Instantaneous and historical temperature effects on α-pinene emissions in Pinus halepensis and Quercus ilex.

6 páginas,4 figuras.We compared the role of instantaneous temperature and temperature history in the determination of α-pinene emissions in Mediterranean conifer Pinus halepensis that stores monoterpenes in resin ducts, and in Mediterranean broad-leaved evergreen Quercus ilex that lacks such specialized storage structures. In both species, α-pinene emission rates (E) exhibited a significant exponential correlation with leaf temperature and the rates of photosynthetic electron transport (JCO 2 +O 2 ) started to decrease after an optimum at approximately 35 o C. However, there was a higher dependence of E on mean temperature of previous days than on mean temperature of current day for P. halepensis but not for Q. ilex. JCO 2 +O 2 showed a maximum relationship to mean temperature of previous 3 and 5 days for P. halepensis and Q. ilex respectively. We conclude that although the best correlation of emission rates were found for instantaneous foliar temperatures, the effect of accumulated previous temperature conOur research on volatile compound emissions has been supported by the funding from the European Science Foundation (Programme VOCBAS), the European Commission Marie Curie research training network ISONET (MC-RTN-CT-2003 504720), the Spanish Government (CGL2006-04025/BOS and ConsoliderIngenio Montes CSD 2008-00040), the Catalan Government (SGR 2009-458), the Spanish National Research council (CSIC-PIF08- 006-3), the Estonian Science Foundation (grant 7645) and the Estonian Ministry of Education and Science (SF1090065s07)Peer reviewe

Changes in monoterpene emission rates of quercus ilex infested by aphids tended by native or invasive lasius ant species

10 páginas, 1 tabla, 2 figuras.The emission of volatile organic compounds (VOCs) depends on temperature and light. Other factors such as insect herbivory also may modify VOC emission. In particular, aphid feeding promotes the release of new compounds and changes the composition of plant volatile blends. Given that some aphids are tended by ants, we investigated whether ants change the emission of VOCs indirectly through attendance on aphids. The effect of Lachnus roboris aphids and two different tending ant species on terpene emission rates of 4-year-old holm oak (Quercus ilex) saplings was investigated during a field experiment. There were five treatments: saplings alone (T1), saplings infested with L. roboris aphids (T2), saplings infested with aphids tended by the local ant Lasius grandis (T3), those tended by small colonies of the invasive ant Lasius neglectus (T4), and those tended by large colonies of the same invasive ant species (T5). The infestation by L. roboris elicited the emission of Δ 3 -carene and increased the emission of myrcene and γ-terpinene. Terpene emissions were modified depending on the tending ant species. Attendance by the local ant L. grandis increased α and β- pinene and sabinene. Attendance by the invasive ant L. neglectus only decreased significantly the emission of myrcene, one of the major compounds of the Q. ilex blend. Aphid abundance decreased with time for all treatments, but there was no difference in aphid abundance among treatments. Total terpene emission rates were not correlated with aphid abundance. These results highlight that aphids and tending ants may change terpene emission rates, depending on the ant species.Funding was provided by MEC/FEDER CGL 2004-05240-CO2/01 and CGL2007-64080-C02-01. Additional funding was provided by grants from the Catalan Government (SGR2009- 458) and the Spanish Government (CGL2006-04025/BOS and Consolider project Montes CSD2008-00040).Peer reviewe

Fuerte control genético y débil modulación ambiental del contenido de terpenos foliares constitutivos e inducidos por metil jasmonato en plántulas de Pinus pinaster

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A deficiency in salicylic acid alters isoprenoid accumulation in water-stressed NahG transgenic Arabidopsis plants

7 páginas, 6 figurasPrevious studies have shown that salicylic acid is an essential component of the plant resistance to pathogens and participates in the plant response to adverse environmental conditions. The present study was aimed at better understanding the response of salicylic acid-deficient transgenic NahG Arabidopsis plants to water deficit conditions, with an especial emphasis on the effects of salicylic acid on isoprenoid accumulation. Total monoterpene contents, chlorophylls and a-tocopherol (which contain a diterpene phytyl moiety in their molecule) and the tetraterpenes, carotenoids, were measured in wild type and NahG Arabidopsis plants exposed to 2 weeks of water deficit. The results show that a salicylic acid deficiency in NahG tansgenic lines suppressed the water stress-induced loss of chlorophylls and carotenoids observed in the wild type. a-Tocopherol accumulation was also affected in NahG plants, which showed lower levels of this antioxidant both under irrigated and water stress conditions. In addition, accumulation of monoterpenes was suppressed in NahG plants both under irrigated and water stress conditions, although the effects were more apparent under stress and, as this was more severe.We conclude that salicylic acid affects isoprenoid accumulation in leaves specially under water stress conditions.This research was supported by REN2003-04871, CGL2004-01402/BOS, CGL2006-04025/BOS and BFU2006- 01127 grants from the Spanish Government, grant ISONET (Marie Curie network contract MC-RTN-CT-2003 504720) from the European Union, a 2004 grant from the Fundacio´n BBVA, and by a SGR2005-00312 grant from Catalan Government.Peer reviewe