somatic embryogenesis is used to produce direct embryo from somatic cells

1. Mrs. Praveen Garg
VITS College, Satna

2.  Somatic embryogenesis is an artificial process in which a plant
or embryo is derived from a single somatic cell.
 Somatic embryos are formed from plant cells that are not
normally involved in the development of embryos, i.e. ordinary
plant tissue.
 No endosperm or seed coat is formed around a somatic embryo.
 It is defined as the development of an embryo, derived from
somatic cells (cells of the embryo sac or the cells surrounding it,
other than gametes) under an appropriate artificial environment
(in-vitro).
 It’s a significant process of tissue culture, as it offers a rapid large-
scale propagation system that is useful for many industries.

4.  The process of fertilization triggers the formation of an
embryo and this mechanistic process is called embryogenesis.
 But fertilization is not the only process of embryo
development?
 Because parthenogenesis is defined as the growth and
development of an embryo without fertilization of the female
gamete.
 In nature, it is observed that tissues that are part of the
embryo sac, or those that surround it, can also develop into an
embryo.
 However, particular environmental conditions, which exist
inside the embryo, will be required for the process. This idea
led to the concept of somatic embryogenesis.

5. J. Reinert (1958-59):
 Reported his first observations of in vitro somatic embryogenesis
in Daucus carota.
F. C. Steward, M. O. Mapes and K. Mears (1958):
 Also reported the somatic embryogenesis in carrot from freely
suspended cells and emphasized the importance of coconut milk
for in vitro somatic embryogenesis
N. S. Rangaswamy (1961):
 Studied in detail the somatic embryogenesis in Citrus sp.
R. N. Konar and K. Nataraja (1969):
 Studied the somatic embryogenesis of Ranunculus sceleratus
using various floral parts (including anthers) as well as somatic
tissues in culture.

6. There are two type of embryogenesis.
 Primary somatic embryogenesis: In this type, the
embryogenesis can only be induced by using the explants.
 Secondary somatic embryogenesis: In this phenomenon, the
development of the embryo is induced through existing
somatic embryos.
 The process of somatic embryogenesis involves four key steps
which are, induction, maintenance, development, and
regeneration.

7. The two ways of inducing somatic embryogenesis include:
 Direct somatic embryogenesis: In this process, the embryo is
developed without any intermediate callus stage. The embryo
can be developed by directly inducing the explant for the
genesis.
 Indirect somatic embryogenesis: In this process, the
development of an embryo occurs with an intermediate callus
stage. So, it is a multistep process.

10.  The first study of somatic embryogenesis was reported in 1958 in
the carrot (Daucus carota).
 However, now more than 300 studies are available for somatic
embryogenesis in various plants.
 In Ranunculus sceleratus, floral tissues are used for
embryogenesis. The medium used to induce the process is 10%
coconut milk with or without IAA and it takes 3 weeks for the
embryo development.
 The somatic embryogenesis is induced in the explants of leaf and
shoot apex of Eucalyptus globulus using media containing 40 μm
Piclogram.
 The formation of the somatic embryo, in the East Indian
sandalwood tree, is induced by using nodal explant on the culture
media, with 2.5 mg/L 2,4-D (Auxin) and 3 mg/L kinetin.

11.  It is a preferred in-vitro propagation method for woody plants.
 It plays a critical role in clonal propagation, synthetic seed
production, germplasm conservation, and cryopreservation.
 It is used for rapid large-scale propagation of plants for the
production of secondary compounds and drugs.
 It is an ideal system for the basic studies of plant cell biology
and embryo development.
 It also provides a better system for the understanding of the
differentiation and mechanism of totipotency expression in
plant cells.

12.  Explant:The choice of explant depends on the species of plant
to be induced for embryogenesis.
 Genotype: The genotypic variation between the plants
also affects the process of embryogenesis.
 Growth Regulators: Auxin, Cytokinin
 Nitrogen Source
 Polyamines
