somaclonal variation

2. TOPIC :- SOMACLONAL VARIATION AND
IT,S CAUSES IN CROP
Ranjeet mauurya

3. Somaclonal Variation
Somaclonal variation refers to genetic variation that arises
in plants regenerated from tissue culture. Tissue culture
involves taking small pieces of plant tissue, such as leaf or
stem, and growing them on a nutrient medium under
controlled conditions to generate whole plants.
Term given by :- Larkin & Scowkraft in 1981

4. Basic Features of Somaclonal Variations
i. Variations in number and structure of chromosomes are
commonly observed.
ii. Regenerated plants with altered chromosomal changes often show
changes in leaf shape and colour, growth rate and habit, and sexual
fertility.
iii. It is generally heritable mutations and persist in plant population
even after plantation into the field.

5. Steps involved in induction and selection of
somaclonal variation
Callus Tissue
Organogenesis
Regenerated Plant
Hardening and Selfing
Somaclonal Variation

6. Causes of Somaclonal
Variation
Physiological
Causes
Genetic Causes
Biochemical
Causes

7.  Physiological Cause
•Exposure of culture to plant growth
regulators.
• Culture conditions

8. •Aneuploidy
•Polyploidy
•Translocation
•Inversion
•Deletion
•Inversion
•Duplication
•Translocation

9. •Transition
•Transversion
•Insertion
• Deletion
iv. Plasmagene Mutation
v. Transposable element activation

10. Biochemical Cause
•Lack of photosynthetic ability due to
alteration in carbon metabolism
•Biosynthesis of starch via carotenoid
pathway
•Nitrogen metabolism
•Antibiotic resistance.

11. 1. Analysis of morphological characters
2. Variant detection by cytological Studies
3. Detection of disease resistance variant.
4. Detection of herbicide resistance
variant.
5. Variant detection by DNA contents
6. Variant detection by gel electrophoresis
7. Detection of environmental stress
tolerant variant

12. Wheat Varieties:'Cham1' (Cham1al): Developed
in Australia
Rice Varieties: 'IR64‘BRRI dhan29'
Maize (Corn) Varieties: Pioneer® Brand Hybrid
Corn Varieties
Tomato Varieties:'UC82B'
The release variety of somaclonal variation

13. Improvement of existing clonal cultures
sugarcane-selections for higher yield & disease
resistance
potatoes-yield & disease resistance
Improved geraniums (esp. scented varieties)
woody ornamentals (e.g., Paulownia-selection

14. Help in crop improvement
Creation of additional genetic variations
Increased and improved production of
secondary metabolites
Selection of plants resistant to various toxins,
herbicides, high salt concentration and mineral
toxicity
Suitable for breeding of tree species

15. • A serious disadvantage occurs in operations which require
clonal uniformity, as in the horticulture and forestry industries
where tissue culture is employed for rapid propagation of elite
genotypes
•Sometime leads to undesirable results
•Selected variants are random and genetically unstable
•Require extensive and extended field trials
•Not suitable for complex agronomic traits like yield, quality etc.
•May develop variants with pleiotropic effects which are not true