Influence of ozone treatments on in vitro propagation of Aloe barbadensis in continuous immersion bioreactor

A feasible methodology for commercial production from shoots of Aloe barbadensis Mill. (Liliaceae) was developed in a continuous immersion bioreactor. The values of fresh weight (total and of shoot clusters), growth index, shoots per explants, shoot length and diameter were higher in bioreactor system than in agarized substrate. Bioreactor improved the shoot quality (low FRAP value, MDA and phenol contents) in comparison with shoots grown in agarized substrate. O3 treatments (0, 1, 5, and 15 min per day) were performed to avoid the contaminations in bioreactor and no visible symptoms of hyperhydricity were detected with or without O3 application. Highest values of total fresh weight, growth index and fresh weight of shoot clusters were observed in the control and with 15 min of O3. Levels of APX, FRAP assay, MDA and phenol content were highest in shoots grown under O3 exposure as a direct effect of oxidative stress. Higher concentration of sucrose (60 g l−1) induced a better shoot proliferation and dry matter of explants than with 30 g l−1of sucrose. Also APX, MDA and FRAP assay and total phenolic contents were significantly highest with 60 g l−1 of sucrose. Results provided experimental evidence that the application of continuous immersion bioreactors for the micropropagation of A. barbadensis associated with O3 treatments is a viable and efficient system for automation and large-scale production of quality shoots.