Stress-induced signaling: intraspecific plants communication mediated by volatile organic compounds (VOC)

The ph. D work is based on the investigation about the functions that volatile organic compounds (VOC) play in plant resistance to stress factors (mainly water stress and aphids) and as signal compounds in plant-plant and plant-insect interactions. A new VOC collection chamber was built to calibrate volatile organic compounds emitted from tomato plants by using the headspace-solid phase microextraction (HS-SPME) technical approach. This technique allowed to quantify for the first time dimethyl sulphonio propionate (DMSP), and, thus, dimethyl sulphide (DMS) potential emission in relation to the stress physiology of higher plants. Subsequently, HS-SPME was applied, in a different experiment, leading to the identification of C6 aldehyde (E)-2-hexenal as an induced VOC involved in water stress tolerance mechanisms of pomegranate plants. Then, an experiment was designed to investigate the signal functions of VOCs in plant-plant and tri-trophic interactions. The main result obtained is that methyl salicylate, released by stressed plants, acted as an airborne signal both attracting natural enemies of insect and inducing the up-regulation of genes controlling the defense responses in unstressed neighboring plants.