Can Ozone Alter the Terpenoid Composition and Membrane Integrity of in vitro Melissa officinalis Shoots?

Ozone affects volatile organic compounds that protect plants from biotic and abiotic stress. In vitro Melissa officinalis shoots were exposed to ozone (200 ppb, 3 h) in controlled environmental conditions: leaf pigments, membrane integrity and headspace composition were assayed during fumigation and after the recovery period (3 h from the beginning of the exposure, FBE). At the end of the exposure, no injury was observed in untreated and treated shoots, although an evident increase in lipid peroxidation was reported (+38.5 and +37.2% of TBARS levels in comparison with controls, respectively after 1 and 3 h FBE). The levels of total carotenoids significantly rose as a normal response mechanism to oxidative stress. SPME-GS-MS analysis showed that, as a consequence of the fumigation, the trends in non-terpenoid compounds increased after 1 and 3 h FBE. This suggests that the concentration and the duration of the treatment were enough to cause a breakdown of cells (as evidenced by increased TBARS levels) and involves an association between volatile products of the lipoxygenase pathway (LOX products) and membrane degradation