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Rice Genomics and Genetics 2013, Vol. 4, No. 4, 14-27
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24
using traditional seed technology practices.
7. Genetic variability: Genetic variability for
regeneration via somatic embryogenesis has been
documented. Genetic control of regeneration capacity
is largely additive and highly heritable.
8. Coating material may limit synthetic seed
production: The coating materials may also limit
success of synthetic seed technology. The hydrated
capsules are more difficult to store because of the
requirement of embryo respiration. A second problem
is that capsules dry out quickly unless kept in a humid
environment or coated with a hydrophobic membrane.
Calcium alginate capsules are also difficult to handle,
because they are very wet and tend to stick together
slightly. In addition, calcium alginate capsules lose
water rapidly and dry down to a hard pellet within a
few hours when exposed to the ambient atmosphere.
The coating material should be non-damaging to the
embryo, mild enough to protocol the embryo and
allow germination and be sufficiently durable for
rough handling during manufacture,
storage,
transportation and planting.
8 Conclusion
The synthetic seed production technology is
constrained due to several major problems, which
hinder its commercialization. The first requirement for
the practical application of synthetic seed technology
is large-scale production of high quality
micropropagules, which is at present a limiting factor.
The second limiting factor is the survival and
germination of the encapsulated somatic embryos are
low. Poor germination of synthetic seeds may be due
to lack of nutrient and/or oxygen supply, microbial
infection and mechanical damage of the embryo. The
conversion of desiccated somatic embryos to plantlets
is low. The desiccation process, which damages the
embryos, and other problems associated with
desiccated synthetic seeds need regulation. Third
major obstacle in synthetic seed technology is
reduction in viability on storage. Most of the research
efforts reflect on short-term storage only. Further
research is needed for prolong maintenance viability
somatic embryos. Either hydrated calcium alginate
based or desiccated polyoxyethylene glycol based
artificial seeds might be used, but it is likely that some
degree of drying before cryopresevation would be
beneficial. Occurrence of somaclonal variation in
tissue culture is another aspect to be considered which
recommending the use of synthetic seeds for clonal
propagation. In nutshell, somatic seed remains a poor
analog of natural seed in terms of viability, handling
and storage. More basic comparative biochemical and
physiological research is needed to understand the
differences in response between zygotic and somatic
seed, so as to determine whether or not somatic
embryo is behaving like recalcitrant seed and/or like
an isolated zygotic embryo in vitro. Synthetic seed
technology provides a rich analog of natural seed in
terms of clonal propagation, handling in national and
international exchange of seeds for genetic
improvement and germplasm conservation.
Author contributions
The first author developed the concept, guided the
second author for collection of referenced articles and
both have contribution in compilation and correction
of this review article in the present shape. Both
authors read and approved the final manuscript.
References
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