Somatic hybridization in higher plants
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Transcript of Somatic hybridization in higher plants
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Somatic Hybridization in higher plants
Presented To: CoordinatorPresented By: Maryam RiazRoll No: M15-08Department of BotanyUniversity of The Punjab, Lahore
3Contents 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
4Hybridization• Process of combining different varieties of organisms to create a hybrid• It may be
Interspecific Hybridizatio
n
Intraspecific
Hybridization
Intergeneric
Hybridization
Intrageneric
Hybridization
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Somatic HybridizationTechnique which allows the manipulation of cellular genomes by protoplast fusion.
6Need 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
7Somatic 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 familyo Brassicaceaeo Fabaceaeo Poaceaeo Solanaceaeo Citrus family
8Technique of Somatic hybridization
Fusion of protoplast
Selection of Hybrid
cells
Identification of
hybrid cells
Regeneration of
hybrid plants
9Fusion 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
10Steps of Somatic Fusion
Formation of protoplast
Fusion of nucleus to
form heterokaryo
n
Formation of cell wall by hormones
Formation of somatic hybrids
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Enzyme treatment to dissolve cell wall
Chemical or electrical stimuli
Cell fusion
Cell nucleus fusion
Protoplasts
Plant leaf
Procedure for Protoplast Fusion
12Selection of Hybrids• Much time and effort is required• Based on visual identificationo 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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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
15Family 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.
16Family 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
17Family 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
18Citrus 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
19Importance 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
20Limitations 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
21Work 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
22Conclusion• 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
23References• 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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