The use of continuous, temporary immersion bioreactor system and semisolid culture medium for the production of Eucalyptus camaldulensis clones

Abstract

The plant micro-propagation in bioreactor systems is regarded as one way to reduce cost by automation and production scheduling. This research was carried out in order to obtain an efficient procedure for clone production of Eucalyptus camaldulensis on different types of bioreactor including continuous and temporary immersion bioreactor. To do so, the apical meristems (1 mm) and the apical meristems with adjacent tissue (2,5 mm) were used as initial explants. These tissues were cultured, for 60 days, in semisolid culture medium supplemented with 1 mg L-1 indole acetic acid (IAA) and 0.32 mg L-1 benzylaminopurine (BA). After 60 days, the meristems with adjacent tissue were transferred to a continuous immersion bioreactor and maintained in dark or light conditions. In order to verify the effect of the explant source on bioreactor multiplication, the explants subcultured from meristems multiplied in semisolid culture medium and the meristems multiplied in continuous immersion bioreactor were tested and maintained in dark conditions. After establishing this parameters, the multiplication experiments were carried out in continuous and temporary immersion and the multiplied explants were then rooted in MS medium supplemented with 0, 2, 4, 8 and 20 mg L-1 indole butyric acid (IBA) and kept in the dark or under controlled lighting conditions. After that, the rooting the plants were acclimatized in mist chamber. The meristem with adjacent tissue favored a greater number of buds/explants. The continuous immersion bioreactor in the dark provided higher shoots number and multiplication rate. The rooting was better on culture medium without auxin and kept in the dark for 15 days or the culture medium supplemented with auxin and maintained under light with 100% plantlet rooting. The Eucalyptus camaldulensis acclimatization was efficient, with high survival rate (76%). It was possible to establish the procedure for bioreactor micro-propagation of Eucalyptus camaldulensis large-scale clones.