Shoot regeneration from leaf explants of five strawberry (Fragaria x ananassa) cultivars in temporary immersion bioreactor system

A temporary immersion bioreactor system (TIB system) provides a convenient and efficient way to propagate plant material in vitro while requiring significantly lower labor input than conventional methods. The applicability of a TIB system for adventitious shoot regeneration from strawberry leaf explants was studied. Five commercial cultivars, i.e. Bounty, Jonsok, Korona, Polka, and Zephyr, were propagated in regeneration medium in commercially available TIB bioreactors (RITA((R))) and, for comparison, on the same medium solidified with agar. The TIB system proved to be well suited for shoot propagation and for subsequent subculture of the developing plantlets. Regeneration frequencies were 70 +/- 8 to 94 +/- 2% and 83 +/- 5 to 92 +/- 3% in the TIB system and on semi-solid medium, respectively. The labor time taken by the TIB system was less than half of the time required for handling plant material for cultivation on semi-solid medium. This system thus provides a convenient method that could be adopted for commercial in vitro propagation or for regeneration of transgenic strawberry cultivars.