VOLATILE ORGANIC COMPOUND EMISSIONS FROM QUERCUS GENUS UNDER ABIOTIC STRESSES

Volatile organic compounds (VOC) emitted by the plants constitute a sensitive signal of stress response. Quantitative relationships between volatile emissions and the stress severity have been demonstrated only for a few stresses. Among important stresses, heat stress can particularly significantly influence all the metabolic processes of the deciduous trees. We studied the effects of heat shock treatments on leaf photosynthesis and the emission of the volatile products of lipoxygenase pathway (LOX) and mono- and sesquiterpene emissions in Quercus genus (including here Q. robur, Q. petraea, Q. cerris, and Q. rubra) to gain quantitative insight into temperature stress elicited volatile emissions. Heat stress treatments ranged from mild that only weakly affected foliage photosynthesis to severe that almost completely inhibited photosynthesis. As well it have been demonstrated that all photosynthetic parameters are less affected for the plants which emit isoprenes due to the thermo-protector role of this VOC. Under non-stressed conditions, LOX emissions were close to detection limit, and terpene emissions were low. The emission of all metabolic compounds exhibit “breaking points” which are species specific. We suggest that the quantitative relationships between the stress strength and emissions observed in this study provide an important means to characterize the severity of cold and heat stresses.