A. M. Yáñez-Serrano, L. Fasbender, J. Kreuzwieser, D. Dubbert, S. Haberstroh, R. Lobo-do-Vale, M. C. Caldeira, C. Werner Diterpene and other isoprenoid emissions by Mediterranean Cistaceae shrubs 1 Photo by C. Werner Isoprenoids • Isoprene Biosynthesis Number C Volatility - Isoprenoid metabolic pathway • Monoterpenes - MEP (plastids) - MVA (cytosol) • Sesquiterpenes Roles - Oxidation protection at cell level • Diterpenes - Signalling compounds - Atmospheric impact • Sesterterpenes - Reactivity - SOA formation • Triterpenes • Tetraterpenes • Polyterpenes 2 Choice of plant family: Cistaceae shrubs Mediterranean region • High temperature and radiation • favor BVOC emissions • Climate change preditions • Increased abiotic stresses • Shrub expansion (Caldeira et al., 2015) • Strong influence in atmospheric chemistry (O3 formation) Expansion and contraction of Mediterranean biome Klausmeyer and Shaw, 2009 PLoSONE 3 Halimium halimifolium Cistus ladanifer Objective To investigate the isoprenoid emissions of two characteristic Mediterranean shrub species • BVOC emission measurements (controlled and natural conditions) • Plant material extraction Information on biosynthesis of the 13 • C-pyruvate labelling via transpiration stream emitted compounds 4 Methodological set up Controlled conditions: Natural conditions: Uni Freiburg Alentejo, Portugal Halimium halimifolium Cistus ladanifer PTR-TOF-MS and GC-MS GC-MS 5 We found the diterpene Kaurene !!! PTR-TOF-MS GC-MS 273.2 274.2 6 Diurnal courses of kaurene for H. Halimfolium 7 Diurnal courses of isoprene, monoterpenes and sesquiterpenes for H. Halimfolium Isoprene Monoterpenes Sesquiterpenes 8 Plant material extraction Relation between emissions and pools suggests diterpene emissions come from storage pools 9 Labelling experiment Indication of freshly produced BVOC 13C-pyruvate labelling experiment suggests diterpenes emissions do not come from de novo biosynthesis 10 Natural conditions – temperature dependency 11 Conclusions from this study • Two Cistaceae species emit considerable amount of diterpenes • Strong diversity in emissions magnitude • Diterpene emissions derive from storage pools • Plant extraction • Labelling • Possible temperature dependency – as seen with the natural conditions data 12 Implications • High reactivity of kaurene • Towards ozone 1.2x10-17 cm3 molec-1 s-1 Similar to a-pinene (EPI) • Towards OH 7.2x10-13 cm3 molec-1 s-1 • Unknown role on aerosol formation potential • Missing reactivity • No consideration of this type of compound in any atmospheric chemistry model 13 Acknowledgement • We thank Boris Bonn and Efstratios Bourtsoukidis for fruitful discussions. • ERC grant number: #647008 Thank you for listening Any questions? 14 15 Direct comparison GC-MS vs PTR-ToF-MS 16 Comparison • Diterpenes are emitted by Mediterranean shrub species in similar magnitudes to monoterpeneoids and sesquiterpenoids • H. Halimifloium is not an isoprene emitter consistent with other Cistaceae species Unit This study Matsunaga et al., Jardine et al., Bracho-Nunes et -1 -1 2012 2014 al., 2013 µg gdw h H.Halimifolium Mediterranean C. Ladanifer Japanese ecosystems H.Halimifolium species 0.15 to 5.38 0.01 to 7.1 - - Diterpenes average of 0.53 average of 0.61 Monoterpenoids 0.62 - 0.7 16.18-0.13 Sesquiterpenoids 2.1 - 2.43 0.03-0.63 17.