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Hybridization

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Hybridization

  1. 1. HYBRIDIZATIONHYBRIDIZATION
  2. 2. DefinitionDefinition  When a plant or animal is bred with a plant or animal from different stock, the process is known as hybridization
  3. 3. Types of Hybridization on the basis of cell type involve in crossing over 2.SomaticHybridization1.Hybridization in sex cell
  4. 4. Types of Hybridization on the taxonomic relationship of the two parents, hybridization classified into two broad groups. 1.Intervarietal Hybridization 2.Distant Hybridization INTRASPECIFIC INTERSPECIFIC Intra generic Inter generic
  5. 5. 1.Intervarietal1.Intervarietal HybridizationHybridization  The parents involved in hybridizationThe parents involved in hybridization belong to the same species. In cropbelong to the same species. In crop improvement programme this type ofimprovement programme this type of hybridization is commonly usedhybridization is commonly used  e. g crossing of two varieties of wheat ore. g crossing of two varieties of wheat or other crops..other crops..
  6. 6. a) INTRASPECIFIC HYBRIDISATION  Crosses are made between twoCrosses are made between two individuals of same species.individuals of same species.  such as between the Bengal tiger andsuch as between the Bengal tiger and Siberian tigerSiberian tiger  This crosses are done to improve selfThis crosses are done to improve self pollinated crops producing.pollinated crops producing.
  7. 7. b)INTERSPECIFIC HYBRIDISATION:  Crosses are made betweenCrosses are made between individual of different varieties of theindividual of different varieties of the same species.same species.  such as between lion and tigerssuch as between lion and tigers  This crosses are made to improveThis crosses are made to improve self pollinated and certain crossself pollinated and certain cross pollinated crops.pollinated crops.
  8. 8. MuleMule HorseHorse ++ DonkeyDonkey
  9. 9. 2) Distant2) Distant Hybridization:Hybridization:  The parents involved belong to theThe parents involved belong to the different species of the same genus or ofdifferent species of the same genus or of different genera.different genera.  TypesTypes I.I. IntragenericIntrageneric II.II.IntergenericIntergeneric
  10. 10. a)INTRAGENERICa)INTRAGENERIC HYBRIDISATION:HYBRIDISATION: Crosses are made between twoCrosses are made between two individuals of different species belonging toindividuals of different species belonging to same genera.same genera. such as between bison and cow.such as between bison and cow. it is used to produce resistance varietiesit is used to produce resistance varieties from diseases ,frost or drought.from diseases ,frost or drought.
  11. 11. BeefaloBeefalo CowCow ++ BisonBison
  12. 12. b)INTERGENERICb)INTERGENERIC HYBRIDISATION:HYBRIDISATION:  Crosses are made between twoCrosses are made between two individuals of different genera belongingindividuals of different genera belonging to same family.to same family.  It produces resistance varieties as wellIt produces resistance varieties as well as desirable combination of allas desirable combination of all characters.characters.  Eg:Brassica X Raphanus Raphanusbrassica
  13. 13. TriticaleTriticale WheatWheat ++ RyeRye
  14. 14. Example of hybrid organismExample of hybrid organism An ornamental lily hybrid known as Lilium 'Citronella' A "Zonkey", a zebra/donkey hybrid A sterile Trillium hybrid between Trillium cernuum and Trillium grandiflorum
  15. 15. SOMATIC HYBRIDIZATIONSOMATIC HYBRIDIZATION
  16. 16. Development of hybrid plants throughDevelopment of hybrid plants through the fusion of somatic protoplasts of twothe fusion of somatic protoplasts of two different plant species/varieties is calleddifferent plant species/varieties is called somatic hybridizationsomatic hybridization
  17. 17. Somatic hybridization technique 1. isolation of protoplast1. isolation of protoplast 2. Fusion of the protoplasts of desired species/varieties2. Fusion of the protoplasts of desired species/varieties 3. Identification and Selection of somatic hybrid cells3. Identification and Selection of somatic hybrid cells 4. Culture of the hybrid cells4. Culture of the hybrid cells 5. Regeneration of hybrid plants5. Regeneration of hybrid plants
  18. 18. 1.Isolation of Protoplast (Separartion of protoplasts from plant tissue)) 1. Mechanical Method 2. Enzymatic Method
  19. 19. 1. Mechanical Method Plant Tissue Collection of protoplasm Cells Plasmolysis Microscope Observation of cells Cutting cell wall with knife Release of protoplasm
  20. 20. 1. Mechanical Method  Used for vacuolated cells like onion bulbUsed for vacuolated cells like onion bulb scale, radish etc.scale, radish etc.  Low yield of protoplastLow yield of protoplast  Laborious and tedious processLaborious and tedious process  Low protoplast viabilityLow protoplast viability
  21. 21. Enzymatic Method Leaf sterlization, removal of epidermis Plasmolysed cells Plasmolysed cells Pectinase +cellulase Pectinase Protoplasm released Release of isolated cells cellulase Protoplasm released Isolated Protoplasm
  22. 22. Enzymatic Method  Used for variety of tissues and organs including leaves, petioles, fruits, roots, ,stem, shoot apices, embryo microspores  Mesophyll tissue - most suitable source  High yield of protoplast  Easy to perform  More protoplast viability
  23. 23. 2.Protoplast Fusion2.Protoplast Fusion (Fusion of protoplasts of two different genomes)(Fusion of protoplasts of two different genomes) 1. Spontaneous Fusion 2. Induced Fusion Intraspecific Intergeneric Electrofusion Mechanical Fusion Chemofusion
  24. 24. 1. Spontaneous Fusion  Protoplast fuse spontaneously duringProtoplast fuse spontaneously during isolation process mainly due to physicalisolation process mainly due to physical contactcontact a)a) Intraspecific produce homokaryonesIntraspecific produce homokaryones b)b) Intergeneric have no importanceIntergeneric have no importance
  25. 25. 2. Induced Fusion a)a) Chemofusion- fusion induced by chemicalsChemofusion- fusion induced by chemicals • Types of fusogensTypes of fusogens • PEGPEG • NaNoNaNo33 • CaCa 2+2+ ionsions • Polyvinyl alcohalPolyvinyl alcohal
  26. 26. Induced Fusion b)b) Mechanical FusionMechanical Fusion Physical fusion of protoplasts underPhysical fusion of protoplasts under microscope by using micromanipulator andmicroscope by using micromanipulator and perfusion micropipetteperfusion micropipette c)c)ElectrofusionElectrofusion Fusion induced by electrical stimulationFusion induced by electrical stimulation
  27. 27. 4.4. Identification and SelectionIdentification and Selection of somatic hybrid cellsof somatic hybrid cells  Hybrid identification- Based on differenceHybrid identification- Based on difference between the parental cells and hybrid cellbetween the parental cells and hybrid cell
  28. 28. Hybrid SelectionHybrid Selection (Several markers are used )(Several markers are used ) • Genetic complementationGenetic complementation • PhytotoxinsPhytotoxins • Specific amino acidSpecific amino acid • Auxin autotrophyAuxin autotrophy • AntibioticsAntibiotics • Auxotrophic and metabolic mutantsAuxotrophic and metabolic mutants • Chromosomal analysisChromosomal analysis • HerbicidesHerbicides
  29. 29. 5. Culture of the hybrid5. Culture of the hybrid cellscells Hybrid cells are cultured onHybrid cells are cultured on suitable medium provided withsuitable medium provided with the appropriate culturethe appropriate culture conditions.conditions.
  30. 30. 6. Regeneration of hybrid6. Regeneration of hybrid plantsplants  Plants are induced to regenerate fromPlants are induced to regenerate from hybrid cellhybrid cell  These hybrid plants must be at leastThese hybrid plants must be at least partially fertile, in addition to havingpartially fertile, in addition to having some useful property, to be of any usesome useful property, to be of any use in breeding schemes.in breeding schemes.
  31. 31. Advantages of somaticAdvantages of somatic hybridizationhybridization  Production of novel interspecific andProduction of novel interspecific and intergenic hybridintergenic hybrid  Pomato (Hybrid of potato and tomato)Pomato (Hybrid of potato and tomato)  Production of fertile diploids and polypoidsProduction of fertile diploids and polypoids from sexually sterile haploids, triploids andfrom sexually sterile haploids, triploids and aneuploidsaneuploids  Transfer gene for disease resistance,Transfer gene for disease resistance, abiotic stress resistance, herbicideabiotic stress resistance, herbicide resistance and many other qualityresistance and many other quality characterscharacters
  32. 32. Advantages of somaticAdvantages of somatic hybridizationhybridization  Production of heterozygous lines in theProduction of heterozygous lines in the single species which cannot besingle species which cannot be propagated by vegetative meanspropagated by vegetative means  Studies on the fate of plasma genesStudies on the fate of plasma genes  Production of unique hybrids of nucleusProduction of unique hybrids of nucleus and cytoplasmand cytoplasm
  33. 33. Limitations of SomaticLimitations of Somatic hybridizationhybridization  Poor regeneration of hybrid plantsPoor regeneration of hybrid plants  Non-viability of fused productsNon-viability of fused products  Not successful in all plants.Not successful in all plants.  Production of unfavorable hybridsProduction of unfavorable hybrids  Lack of an efficient method forLack of an efficient method for selection of hybridsselection of hybrids  No confirmation of expression ofNo confirmation of expression of particular trait in somatic hybridsparticular trait in somatic hybrids

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