5.7.2.1. Synthetic Seeds. Encapsulated somatic embryos are known assynthetic
seeds. Somatic embryos are typically encapsulated in an alginate matrix, which serves as
an artificial seed coat. The encapsulated somatic embryos can be germinated ex vitro or
in vitro to form plantlets. Synthetic seeds have multiple advantages—they are easy to
handle, they can potentially be stored for a long time, and there is potential for scaleup
and low cost of production. The prospects for automation of the whole production
process is another advantage because the commercial application of somatic embryogenesis
requires high-volume production. Synthetic seeds can be stored at 4 8 C for shorter periods or
cryopreserved in liquid nitrogen for long-term storage (Fang et al. 2004). Production of syn-
thetic seeds and germination of these seeds to plantlets has been accomplished in sandal-
wood, coffee, bamboo, and many other plant species.
5.8 Rooting of Shoots
Efficient rooting of in vitro–grown shoots is a prerequisite for the success of micropropa-
gation. The success of acclimatization of a plantlet greatly depends on root system
production. Rooting of trees and woody species is difficult as compared to herbaceous
species. Rooting of shoots is achieved in vitro or ex vitro.Ex vitro(out of glass) rooting
reduces the cost of production significantly. Ex vitro rooting is carried out by pretreating the
shoots with phenols or auxins and then directly planting them in soil under high-humidity
Figure 5.11.(a) Multiple-bud initiation from cotyledonary nodes; (b,c) multiple buds ofMedicago
truncatulaand cashew, respectively, elongate to form shoots; (d) rooting of elongated shoots of
cashew.
5.8. ROOTING OF SHOOTS 127