Influence of ozone treatments on in vitro propagation of Lilium in bioreactor

The aim of this study was to provide a feasible methodology for the commercial production of lily in a continuous immersion bioreactor, using ozone (O₃) to reduce the risk of contaminations in liquid medium caused by the presence of bacteria within the plant tissues. The effects of different O₃ treatments (5, 10 or 15 min day^1-, flow rate of 1.0-2.0 L min^-1) on growth and some physiological and biochemical parameters of Lilium shoots were investigated. The values of fresh weight (total and of shoot clusters), growth index, shoots per explants, and shoot diameter were higher with 5 min than with 10 and 15 min of O₃. Levels of ascorbate peroxidase activity, FRAP assay, and H₂O₂ content were lower in shoot grown under 5 min of O₃ exposure as a direct sign of minor oxidative stress. No differences were observed for other antioxidant enzymes (catalase, guaiacol peroxidase), malonyldialdehyde (MDA) and chlorophyll pigments respect to O₃ treatments. Results provide experimental evidence that the application of continuous immersion bioreactors for the micropropagation of lily associated with O₃ treatments is a viable and efficient model for automation and large-scale production of quality shoots.