Protocols for Micropropagation of Woody Trees and Fruits

342
R.I. IYER
Figure 3. Formation of axillary A) and adventitious B) shoots as well as somatic embryogenesis
in leaves C) of nutmeg. Bars 1 mm.
Formation of adventitious buds in stem explants. Formation of adventitious buds in
stem explants (8 per explant) taken from the apical region was obtained with a
frequency of 20% in medium C2.
Formation of adventitious buds in leaf petioles. Formation of adventitious buds (10
per explant) in leaf petioles (Figure 3B) cultured horizontally was obtained in
medium C3.
Somatic embryogenesis from immature leaf explants. In median segments from
tender leaves formation of globular and elongated somatic embryoids at the margin
on the adaxial surface was obtained after 11 days with a frequency of 90% (Figure
3C) in medium C4.
3. CONCLUSION
A protocol for direct, repetitive somatic embryogenesis and establishment of longterm
embryogenic cultures from zygotic embryos of nutmeg has been developed. In
view of the difficulties of multiplication of this plant by conventional methods the
developed in vitro techniques constitute an important progress, which has a great
potential to generate biomass source for valuable nutmeg compounds with pharmaceutical
values. The extent of the embryogenic response was influenced by the
developmental stage of the zygotic embryos. Activated charcoal and light were
identified as the critical factors for the survival of explants and induction of somatic
embryogenesis. The protocol still needs refinement for the transfer of plantlets to
soil. A protocol for regeneration of single axillary shoots from nodal explants and
somatic embryogenesis from immature leaves has also been described.
Acknowledgements. The author thanks Dr. G. Jayaraman, Reader, Department of Genetics,
University of Madras (Taramani Campus), Chennai-600113 for going through the manuscript
and for his valuable suggestions, Department of Science & Technology, Govt. of India for
financial support in the form of a project under the Women Scientists’ Scheme and Dr. Mohan
Jain for his immensely useful comments.