Photoprotective isoprenoids as physiological markers for the adaptation of Douglas fir to drought stress and climate change

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The aim of this study is to determine the diversity of isoprenoid-related mechanisms of drought tolerance in Douglas fir. Essential isoprenoids such as carotenoids, absicic acid and xanthophylls are present in all green organisms whereas nonessential isoprenoids are common in numerous but not in all plant species. The latter include volatile compounds such as isoprene, monoterpenes and sesquiterpenes. Besides other functions, non-essential isoprenoids are assumed to possess antioxidative properties, mediating protection against oxidative stress such as drought stress or stress by high temperatures. In this study we will analyse patterns and magnitude of volatile isoprenoid emissions by five Douglas fir provenances and elucidate the production of essential isoprenoids (being downstream of the biosynthetic pathway) in the same trees. By using provenances which have evolutionary adapted to contrasting environments, we will be able to relate isoprenoid emission patterns and formation of essential isoprenoids to provenance specific adaptive mechanisms of drought/high temperature tolerance. For this purpose we will use 50 year old trees in the field from large provenance-trials as well as seedlings derived through controlled selfing from the respective provenances in experiments simulating drought.