Articles | Volume 16, issue 12
https://doi.org/10.5194/acp-16-7813-2016
https://doi.org/10.5194/acp-16-7813-2016
Research article
 | 
24 Jun 2016
Research article |  | 24 Jun 2016

Role of needle surface waxes in dynamic exchange of mono- and sesquiterpenes

Johanna Joensuu, Nuria Altimir, Hannele Hakola, Michael Rostás, Maarit Raivonen, Mika Vestenius, Hermanni Aaltonen, Markus Riederer, and Jaana Bäck

Abstract. Biogenic volatile organic compounds (BVOCs) produced by plants have a major role in atmospheric chemistry. The different physicochemical properties of BVOCs affect their transport within and out of the plant as well as their reactions along the way. Some of these compounds may accumulate in or on the waxy surface layer of conifer needles and participate in chemical reactions on or near the foliage surface. The aim of this work was to determine whether terpenes, a key category of BVOCs produced by trees, can be found on the epicuticles of Scots pine (Pinus sylvestris L.) and, if so, how they compare with the terpenes found in shoot emissions of the same tree. We measured shoot-level emissions of pine seedlings at a remote outdoor location in central Finland and subsequently analysed the needle surface waxes for the same compounds. Both emissions and wax extracts were clearly dominated by monoterpenes, but the proportion of sesquiterpenes was higher in the wax extracts. There were also differences in the terpene spectra of the emissions and the wax extracts. The results, therefore, support the existence of BVOC associated to the epicuticular waxes. We briefly discuss the different pathways for terpenes to reach the needle surfaces and the implications for air chemistry.

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Short summary
Plants produce volatile compounds (BVOCs) that have a major role in atmospheric chemistry. Our aim was to see if terpenes, a key group of BVOCs, can be found on surfaces of pine needles and, if so, how they compare with the emissions of the same tree. Both emissions and wax extracts were clearly dominated by monoterpenes, but there were also differences in the emission and wax spectra. The results support the existence of BVOCs on needle surfaces, with possible implications for air chemistry.
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