Analysis of volatiles from Picea abies triggered by below-ground interactions

Information on the volatiles emitted from young trees of e.g., the Norway spruce (Picea abies) is of high ecological interest, since these compounds organize the interaction of the growing plant with the biotic environment. To collect aerial volatiles induced by below-ground factors, cultivation of Picea seedlings on agar was combined with a newly developed volatile collection chamber to allow the separation of below-ground and aerial parts. The aim of this study was to investigate if below-ground root factors, such as mycorrhization or metal contaminated substrates are able to trigger a systemic volatile response of spruce seedlings. Cesium(I), a major contaminant in industrially polluted soils, was used to exert stress, and response was recorded in combination with ectomycorrhiza by the basidomycete Tricholoma vaccinum. The germination rate and growth show a toxic effect of cesium and a positive effect of the fungus on the roots and plant health. A pronounced volatile emission was observed in mycorrhizal seedlings treated with cesium. Without cesium treatment seedlings did not change their volatile emission depending on mycorrhization. However, if seedlings were treated with cesium, those with mycorrhiza emitted tricyclene, alpha- and beta-pinene, camphene, myrcene, limonene, terpinolene, camphor and bornyl acetate. With the newly established volatile collection separated for above-ground and below-ground parts, abiotic and biotic factors can be evaluated with respect to chemodiversity and ecological interactions. (C) 2014 Elsevier B.V. All rights reserved.