Use of the temporary immersion bioreactor system (RITA^®) for production of commercial Eucalyptus clones in Mondi Forests (SA)

Abstract

In order to optimise tissue culture systems and to meet production targets, Mondi Forests’ biotechnology programme has in the last 2 years concentrated efforts on the use of the RITA^® temporary immersion bioreactor system. Protocols have been established for six Eucalyptus clones. Results indicate a four- to six-fold increase in yield, in half the time, with the RITA^® system when compared with axillary bud proliferation on semi-solid media. Furthermore, plants produced from the RITA^® system are hardier and acclimatize better, giving higher yields of hardened-off plants. The establishment of aseptic axillary shoots into the RITA^® system is from shoots in the semi-solid system. Highest multiplication was achieved using 30-second flushes of medium every 10 min, starting with 50 shoots per vessel. The multiplication cycles in RITA^® are between 14 and 18 days, compared with 25–28 days in a semi-solid system. There is minimal callus evident on the leaves and bases of the stems of plants in the RITA^® system and, in addition, cold-tolerant plants have a greater rooting competence when compared with plants coming from the semi-solid system. Ex vitro rooting of RITA^® – derived plantlets is substantially better than the plants from the semi-solid media.