Introduction Types of somatic embryogenesis Developmental stages Factors affecting somatic embryogenesis Importance Conclusions References The process of regeneration of embryos from somatic cells, tissue or organs is regarded as somatic or asexual embryogenesis. opposite of zygotic or sexual embryogenesis. Embryo-like structures which can develop into whole plants in a way that is similar to zygotic embryos are formed from somatic cells.

1. Plant Tissue Culture
“Somatic Embryogenesis”
By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )

2. Contents
 Introduction
 Types of somatic embryogenesis
 Developmental stages
 Factors affecting somatic embryogenesis
 Importance
 Conclusions
 References

3. Introduction
• The process of regeneration of embryos from somatic
cells, tissue or organs is regarded as somatic or asexual
embryogenesis.
• opposite of zygotic or sexual embryogenesis.
• Embryo-like structures which can develop into whole
plants in a way that is similar to zygotic embryos are
formed from somatic cells.

4. History
• First recognized by Steward et al. (1958) and Reinert
(1958, 1959) in culture of Daucus carota.
In this four different stages are there:-
• Initiation stage
• Proliferation stage
• Maturation stage
• Germination

5. Various terms for non-zygotic embryos
• Adventious embryos – somatic embryos arising
directly from other organs or embryos.
• Parthenogenetic embryos – formed by the
unfertilized egg.
• Androgenetic embryos – formed by the male
gametophyte.

6. Types
1. Direct somatic embryogenesis
2. Indirect somatic embryogenesis
Direct embryogenesis
– Somatic embryos develop directly on excised plant without undergoing
callus formation, it referred to as somatic embryogenesis.
– Direct somatic embryogenesis is generally rare.
– The characteristic features of direct embryogenesis is avoiding the
possibility of introducing somaclonal variation in the propagated plants.

7. Indirect somatic embryogenesis
• In indirect embryogenesis, the cells from explant are made to
proliferate and form callus, from which cell suspension cultures
can be raised.
• Certain cells referred to as induced embryogenic determined
cells from the cell suspension can form somatic embryos.
• Embryogenesis is made possible by the presence of growth
regulators & under suitable environment condition.
• Explant → Callus Embryogenic → Maturation → Germination

8. Indirect somatic embryogenesis in carrot (dauctus carota)
Indirect Somatic
embryogenesis

9. Induction -Auxins required for induction.
– Pro embryogenic masses form.
– 2,4-D most used.
Development
• Auxin must be removed for embryo development.
• Continued use of auxin inhibits embryogenesis.
Maturation
• Require complete maturation with apical meristem, radicle, and
cotyledons.
• Germination
• May only obtain 3-5% germination.
• Sucrose (10%), mannitol (4%) may be required.

10. Development patterns
Torpedo embryo

11. Somatic embryogenesis is influenced by several
factors
Explant
Genotype
Growth regulators
Nitrogen source

12. Explant
 Immature zygotic embryos best explant for recalcitrant
species.
 Petiole section from youngest fully expanded leaves
establishment of embryonic cultures of Alfalfa.
 Development of embryos from somatic cells (epidermis,
parenchymatous cells of petioles, secondary root phloem).

13. Genotype
 Explant genotype has a marked influence on SE regeneration.
 Strong genotypic effects have been shown in many species. e.g.
alfalfa, wheat, maize, rice etc.
 In case of wheat, chromosome 4B is important in regeneration.

14. Growth regulators
 Embryo initiation - auxin in the medium is generally essential.
 2, 4-D 0.5 mg per l. - induces differentiation of localized groups
of meristematic cells called embryogenic clumps.
 Embryo development - auxin free media.
CYTOKININS
• Effective concentration range for kinetin is 0.5-5.0 micro M.
• Also important in somatic embryo maturation and cotyledon
development.
• Required for growth of embryos to plantlets.

15. Nitrogen source
 The form of nitrogen has a marked effect on somatic embryogenesis.
 In carrot NH+4 has a promotive effect on SE regeneration.
 SE development medium containing NO-3 as the sole nitrogen source.
 Addition of reduced nitrogen in the medium helps in both embryo
initiation and maturation.
 Other suppliments
• L-glutamine plays an important role among all the amino acids.
• Another factor is the chelated form of iron in the media.
• In absence of Fe, embryo development fails to pass from the globular
to the heart shaped stage.

16. • Presence of auxin in the medium is generally essential for
embryo initiation.
• Tissues maintained continuously in an auxin free medium do not
form embyos.
• When transferred to low auxin medium embryogenic clumps
develop in to mature embryos.
• Light generally promotes embryogenesis.
• High temp. usually favorable for somatic embryogenesis.
16

17. Importance of somatic embryogenesis
 Raising somaclonal variants
 Synthesis of artificial seeds
 Synthesis of metabolites
 Clonal propagation
 Genetic transformation
 Conservation of genetic resources

18. Disadvantage
 High probability of mutations.
 The method is usually rather difficult.
 Losing regenerative capacity become greater with repeated
subculture.
 Induction of embryogenesis is very difficult with many plant
species.
 A deep dormancy often occurs with somatic embryogenesis.

19. References
• Introduction to plant tissue culture By M. K. Razdan 1st
edition
• Plant biotechnology By H. S. Chawla
internet
• www.plant-molecularbiotechnology.com
• www.wikipedia.com/somaticembryos.html