Volatiles emitted from in vitro grown tomato shoots during abiotic and biotic stress

Different stress factors were applied to in vitro grown tomato shoots (Lycopersicon esculentum Mill. 'Moneymaker') to investigate the volatiles released in the headspace. Solid phase microextraction was used for the experiments with an abiotic stress factor (constant light) and automated dynamic sampling was used for the experiments with a biotic stress factor (Spodoptera littoralis caterpillar). Continuous light as stress factor induced constant emission of the sesquiterpene alpha-copaene. Constant emission was not found with any other sesquiterpene or with monoterpenes. Therefore, we hypothesize that this compound needs light for its biosynthesis and/or emission. An attack by caterpillars caused an immediate higher emission of the constitutive compounds (mono- and sesquiterpenes) and the induced compounds (linalool and indole); the latter were emitted approximately 1 day after the attack and linalool was even emitted 2 days after removal of the caterpillar.