Liquid Culture Systems for in vitro Plant Propagation

206 Elio Jiménez González
weeks in culture. Also the size and weight of the tubers were superior
compared to cultures on solid media.
Akita and Takayama (1994) and Teisson and Alvard (1999) also stressed
on the higher efficiency of TIS for potato microtuber production, not only
because more tubers were produced per plant, but also size and weight of the
tubers were increased.
Jiménez et al. (1999) scaled up a mass production protocol of potato
microtubers in 10-litre twin flasks, with cv. Atlantic (Figure 4). Twelve TIS
units were inoculated containing 150 single nodal cuttings each. An average
of 2.6 tubers per inoculated cutting was obtained, with 1.3 g fresh weight per
microtuber.
Field experiments were conducted to compare direct transplantation of
potato microtubers into the field with plants propagated by in vitro cuttings
(Pérez et al., 2000). Plants from microtubers produced in TIS showed an
increased height and more stems per plant compared with plants from in
vitro cuttings, which resulted in increased fresh weight and diameter of the
tubers with statistical significant differences.
Figure 4: Scale up of potato microtuber production in 10-litre TIS (left) and close view of the
microtuber inside the culture vessel (right).
4. Somatic embryogenesis in TIS
TIS can effectively improve the production and quality of somatic
embryos. Escalant et al. (1994) described an increase in embryo number in
several banana and plantain (Musa sp.) cultivars when comparing the yield
from RITA® with that from cultures on agar medium. Somatic embryos of
other tropical species have been successfully multiplied and/or germinated in
TIS, such as Camellia sinensis, Coffea arabica, Coffea canephora, Citrus
deliciosa, Hevea brasiliensis, Psidium guajava (Akula et al., 2001; Etienne