Evaluation of ElecTIS bioreactor for the micropropagation of Malus sylvestris (L.) Mill., an important autochthonous species of Albania

Malus sylvestris (L.) Mill., an economically-important fruit tree, is native to Albania and in many parts of Europe. It is cultivated as an ornamental tree, while its fruits are collected for food and a source of antioxidant substances. It is included in The IUCN Red List of Threatened Species. For these reasons, it is very important to optimise a micropropagation protocol, in order to obtain great numbers of clonal plantlets for ex situ conservation and production purposes. A liquid culture in a temporary immersion system (TIS) is a recently-proposed system for large-scale in vitro plant propagation. In this study, lateral buds of M. sylvestris were inoculated in MS medium with BAP (1 mg/L) and NAA (0.1 mg/L). In order to avoid oxidative stress, different antioxidants were previously tested with the culture in a gelled medium, and the combination of ascorbic acid and citric acid (both at 100 mg/L) was selected for the following culture in TIS. Stabilised explants were then cultivated in ElecTIS, an innovative TIS bioreactor, and in a semisolid medium, after which the two culture systems were evaluated. Overall, the ElecTIS showed to be more effective for all the tested parameters.