Poster: Secondary Metabolism

Abs # 307: Silver birch clones are capable of emitting high amounts of terpenes under stress

Presenter:	Vuorinen, Terhi , terhi.vuorinen@uku.fi
Authors	Vuorinen, Terhi  (A)   Manninen, Anne-Marja  (A)   Vapaavuori, Elina  (B)   Holopainen, Jarmo K (A)
Affiliations:	(A): University of Kuopio, Department of Ecology and Environmental Science, Finland (B): Finnish Forest Research Institution

Emission of volatile organic compounds (VOCs) were analyzed from two clones of Betula pendula trees exposed three years to CO₂ and O₃, singly and in combination, in open-top chamber system. VOC measurements were performed in early July and in late August. Both clones of silver birch emitted similar profile of VOCs. The emission in July was dominated by sesquiterpenes germacrene D, (E,E)-a-farnesene, a-copaene, b-bourbonene and aromadendrene. The main monoterpenes emitted in July were (E)-b-ocimene and (Z)-ocimene. The emission in August was dominated by monoterpenes (E)-b-ocimene and (Z)-ocimene, and the main sesquiterpenes were (E,E)-a-farnesene, a-copaene, b-bourbonene and b-caryophyllene. The emission rate of total monoterpenes, total sesquiterpenes, and total VOCs from both silver birch clones was higher in July than in August. Elevated CO₂ treatment slightly decreased total monoterpene emission from silver birch trees in July, while in August the total monoterpene emission was enhanced by CO₂ exposure. Also, total VOC emission increased significantly in August in elevated CO₂ concentration. O₃-exposure or O₃/CO₂-exposure did not have any effect on total monoterpene, sesquiterpene or VOC emissions. The effects of elevated CO₂ on leaf area index and total VOC emission is discussed.