somatic hybridization is a technique which allows manipulation of cellular genomes by protoplast diffusion...

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2. Presented To: Coordinator
Presented By: Maryam Riaz
Roll No: M15-08
Department of Botany
University of The Punjab, Lahore
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3. Contents
 Hybridization
 Somatic Hybridization
 Need of somatic hybridization
 Somatic hybridization in higher plants
 Technique of somatic hybridization
 Brassicaceae
 Fabaceae
 Poaceae
 Solanaceae
 Citrus Family
 Importance of SH
 Limitations of SH
 Work in Pakistan
 Conclusion
 References
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4. Hybridization
• Process of combining different varieties
of organisms to create a hybrid
• It may be
Interspecific
Hybridization
Intraspecific
Hybridization
Intergeneric
Hybridization
Intrageneric
Hybridization
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5. Somatic
Hybridization
Technique which allows
the manipulation of
cellular genomes by
protoplast fusion.
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6. Need Of Somatic Hybridization
 crossing barriers among plant species and in organelle
genetics and breeding
 Species barriers encountered in sexual hybridization
 transfer of genes from wild species into the genes of crop
plants
 tool for the modification and improvement of polygenic
traits
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7. Somatic Hybridization in Higher Plants
• Diploid protoplast have been used for somatic hybrids
• PEG is commonly used for inducing fusion
• Somatic cells are produced only in early stages
• Recently used in various crops within family
o Brassicaceae
o Fabaceae
o Poaceae
o Solanaceae
o Citrus family
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8. Technique of Somatic hybridization
Fusion of
protoplast
Selection of
Hybrid cells
Identification
of hybrid cells
Regeneration
of hybrid
plants
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9. Fusion of Protoplast
• Also called somatic fusion
• It is a fusion of two distinct forms of plant to form a somatic
hybrid
• It may be achieved by
Spontaneous
fusion
Mechenical
fusion
Induced fusion
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10. Steps of Somatic Fusion
Formation of
protoplast
Fusion of
nucleus to form
heterokaryon
Formation of cell
wall by
hormones
Formation of
somatic hybrids
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11. Enzyme treatment to dissolve cell wall
Chemical or electrical stimuli
Cell fusion
Cell nucleus
fusion
Protoplasts
Plant leaf
Procedure for Protoplast Fusion
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12. Selection of Hybrids
• Much time and effort is required
• Based on visual identification
o Differentially stained protoplasts
Identification Of Hybrids
• By observing morphology
• By using PCR
Regeneration of Hybrid Plants
• Fulfilment of all the conditions and requirements for
organogenesis
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14. Family Brassicaceae
• Model family for somatic hybridization
• Hybridization have been performed in Brassica genus
• Resynthesis of Brassica napus, an intergeneric hybrid
• Intertribal hybrid are also produced e.g., Raphanus x B.napus
Fig: Intertribal hybridization b/w Raphanus and Brassica
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15. Family Fabaceae
• Regeneration of plants was initially
troublesome
• Now achieved in several genera like
Pisum,Trifolium,especially in Medicago
• Flowering hybrids b/w Medicago sativa &
Medicago falcate
• Intergeneric fusion b/w Onobrychis
viciifolia, Sanfoin & Alfalfa
Fig: Flowering hybrids of Medicago spp.
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16. Family Poacae
• Somatic hybridization was initially difficult
• Now several intergenric and intrageneric
have been produced
• e.g., Panicum maximum (+) Pennisetum
americanum, Saccharum officinarum (+)
P. americanum etc
• Much work has been done on
Saccharum spp.
Fig: Somatic plant regeneration of grass
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17. Family Solanaceae
• For disease & insect resistance in eggplant,
Solanum melongena
• To restore the ploidy level and for viral resistance
in potato
• In Tomato, several interspecific hybrid plants have
been produced
• E.g., Tomato + Solanum etuberosum, Tomato +
Nicotiana tabacum, Tomato + S. tuberosum etc
Tomato
Potato
Eggplant
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18. Citrus Family
• Somatic embryogenesis and plant
regeneration are basic processes
• Production of allotetraploid somatic
hybrids is most important
• For the recovery of cybrid plants
Fig: Citrus fruit varieties
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19. Importance of Somatic hybridization
• Introgression of traits from (wild) species into cultivars
• New combinations of nucleus and organelles for the creation of
cytoplasmic male sterility (CMS)
• Provides an alternative approach to colchicine treatment
• Several interspecific and inter-generic hybrids with disease
resistance
• Introduction of genes responsible for the tolerance of cold, frost
and salt
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20. Limitations of somatic hybridization
• Does not always produce plants that give fertile and viable
seeds
• Frequently associated with genetic instability
• Production of viable somatic hybrids is not possible in all
instances
• Limitations in the selection methods of hybrids
• No certainty as regards the expression of any specific
character
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21. Work on Somatic Hybridization in
Pakistan
• Much work has been done in various research institutes and
labs
• In Punjab University, much work on sugarcane
• E.g., the protoplast cultures,
• in vitro callus cultures of sugarcane,
• electrofusion in sugarcane protoplasts
• regeneration of sugarcane embryos
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22. Conclusion
• Somatic Hybridization, a technique for the manipulation of
cellular genomes by protoplast fusuion
• Species barrier in sexual hybridization is encounterd
• Used in various crop production in higher plants
• Produce genetic variability and disease resistance in various
crops
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23. References
• http://www.yourarticlelibrary.com/biology/plants/hybridization-in-plants-types-
procedure-and-consequence-of-hybridization/23340/. 11/11/2016
• P. Aleza, A. Garcia-Lor, J. Juarez and L. Navarro. 2016. Recovery of citrus cybrid
plants with diverse mitochondrial and chloroplastic genome combinations by
protoplast fusion followed by in vitro shoot, root, or embryo micrografting. Plant
Cell Tiss Organ Cult. [Vol.126]: 205–217
• Oluf L. Gamborg, F. Constabel, L. Fowke, K. N. Kao, K. Ohyama, K. Karthaa, and
L. Pelcher. 1974. Protoplast and cell culture methods in Somatic hybridization in
higher plants. Can. J. Genet. Cytol. [Vol.16]: 737-750
• Melchers. G and G. Labib. 1974. Somatic Hybridisation of Plants by Fusion of
Protoplasts. Molec. Gen. Geneg. [Vol.135], 277-294
• Waara. S & K. Glimelius. 1995. The potential of somatic hybridization in crop
breeding. Euphytica [vol.85]: 217-233, 1995
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