Hybridization

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1. HYBRIDIZATIONHYBRIDIZATION

2. DefinitionDefinition
When a plant or animal is bred with a
plant or animal from different stock, the
process is known as hybridization

3. Types of Hybridization
on the basis of cell type involve in crossing over
2.SomaticHybridization1.Hybridization in sex cell

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. 1.Intervarietal 1.Intervarietal
HybridizationHybridization
The parents involved in hybridization The parents involved in hybridization
belong to the same species. In crop belong to the same species. In crop
improvement programme this type of improvement programme this type of
hybridization is commonly used hybridization is commonly used
e. g crossing of two varieties of wheat or e. g crossing of two varieties of wheat or
other crops..other crops..

6. a) INTRASPECIFIC
HYBRIDISATION
Crosses are made between two Crosses are made between two
individuals of same species.individuals of same species.
such as between the Bengal tiger and such as between the Bengal tiger and
Siberian tigerSiberian tiger
This crosses are done to improve self This crosses are done to improve self
pollinated crops producing.pollinated crops producing.

7. b)INTERSPECIFIC
HYBRIDISATION:
Crosses are made between Crosses are made between
individual of different varieties of the individual 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 improve This crosses are made to improve
self pollinated and certain cross self pollinated and certain cross
pollinated crops.pollinated crops.

8. MuleMule
HorseHorse
++
DonkeyDonkey

9. 2) Distant 2) Distant
Hybridization:Hybridization:
The parents involved belong to the The parents involved belong to the
different species of the same genus or of different species of the same genus or of
different genera. different genera.
TypesTypes
I.I.IntragenericIntrageneric
II.II.IntergenericIntergeneric

10. a)INTRAGENERIC a)INTRAGENERIC
HYBRIDISATION:HYBRIDISATION:
Crosses are made between two Crosses are made between two
individuals of different species belonging to individuals 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 varieties it is used to produce resistance varieties
from diseases ,frost or drought.from diseases ,frost or drought.

11. BeefaloBeefalo
CowCow
++
BisonBison

12. b)INTERGENERIC b)INTERGENERIC
HYBRIDISATION:HYBRIDISATION:
Crosses are made between two Crosses are made between two
individuals of different genera belonging individuals of different genera belonging
to same family. to same family.
It produces resistance varieties as well It produces resistance varieties as well
as desirable combination of all as desirable combination of all
characters.characters.
Eg:Brassica X Raphanus
Raphanusbrassica

13. TriticaleTriticale
WheatWheat
++
RyeRye

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. SOMATIC HYBRIDIZATIONSOMATIC HYBRIDIZATION

16. Development of hybrid plants through Development of hybrid plants through
the fusion of somatic protoplasts of two the fusion of somatic protoplasts of two
different plant species/varieties is called different plant species/varieties is called
somatic hybridizationsomatic hybridization

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 plants 5. Regeneration of hybrid plants

18. 1.Isolation of Protoplast
(Separartion of protoplasts from plant tissue))
1. Mechanical Method
2. Enzymatic Method

19. 1. Mechanical Method
Plant Tissue
Collection of protoplasm
Cells Plasmolysis
Microscope Observation of cells
Cutting cell wall with knife
Release of protoplasm

20. 1. Mechanical Method
Used for vacuolated cells like onion bulb Used 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. 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. 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. 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. 1.Spontaneous Fusion
Protoplast fuse spontaneously during Protoplast fuse spontaneously during
isolation process mainly due to physical isolation process mainly due to physical
contactcontact
a)a)Intraspecific produce homokaryonesIntraspecific produce homokaryones
b)b)Intergeneric have no importanceIntergeneric have no importance

25. 2. Induced Fusion
a)a)Chemofusion- fusion induced by chemicalsChemofusion- fusion induced by chemicals
•Types of fusogensTypes of fusogens
•PEGPEG
•NaNoNaNo
33
•Ca Ca
2+2+
ions ions
•Polyvinyl alcohalPolyvinyl alcohal

26. Induced Fusion
b) b) Mechanical FusionMechanical Fusion
Physical fusion of protoplasts under Physical fusion of protoplasts under
microscope by using micromanipulator and microscope by using micromanipulator and
perfusion micropipetteperfusion micropipette
c)c)ElectrofusionElectrofusion
Fusion induced by electrical stimulationFusion induced by electrical stimulation

27. 4. 4. Identification and Selection Identification and Selection
of somatic hybrid cellsof somatic hybrid cells
Hybrid identification- Based on difference Hybrid identification- Based on difference
between the parental cells and hybrid cell between the parental cells and hybrid cell

28. Hybrid SelectionHybrid Selection
(Several markers are used )(Several markers are used )
•Genetic complementationGenetic complementation
•Phytotoxins Phytotoxins
•Specific amino acidSpecific amino acid
•Auxin autotrophyAuxin autotrophy
•AntibioticsAntibiotics
•Auxotrophic and metabolic mutantsAuxotrophic and metabolic mutants
•Chromosomal analysisChromosomal analysis
•HerbicidesHerbicides

29. 5. Culture of the hybrid 5. Culture of the hybrid
cellscells
Hybrid cells are cultured on Hybrid cells are cultured on
suitable medium provided with suitable medium provided with
the appropriate culture the appropriate culture
conditions.conditions.

30. 6. Regeneration of hybrid 6. Regeneration of hybrid
plantsplants
Plants are induced to regenerate from Plants are induced to regenerate from
hybrid cell hybrid cell
These hybrid plants must be at least These hybrid plants must be at least
partially fertile, in addition to having partially fertile, in addition to having
some useful property, to be of any use some useful property, to be of any use
in breeding schemes. in breeding schemes.

31. Advantages of somatic Advantages of somatic
hybridizationhybridization
Production of novel interspecific and Production of novel interspecific and
intergenic hybridintergenic hybrid
 Pomato (Hybrid of potato and tomato)Pomato (Hybrid of potato and tomato)
Production of fertile diploids and polypoids Production of fertile diploids and polypoids
from sexually sterile haploids, triploids and from sexually sterile haploids, triploids and
aneuploidsaneuploids
Transfer gene for disease resistance, Transfer gene for disease resistance,
abiotic stress resistance, herbicide abiotic stress resistance, herbicide
resistance and many other quality resistance and many other quality
characterscharacters

32. Advantages of somatic Advantages of somatic
hybridizationhybridization
Production of heterozygous lines in the Production of heterozygous lines in the
single species which cannot be single 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 nucleus Production of unique hybrids of nucleus
and cytoplasmand cytoplasm

33. Limitations of Somatic Limitations 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 for Lack of an efficient method for
selection of hybridsselection of hybrids
No confirmation of expression of No confirmation of expression of
particular trait in somatic hybridsparticular trait in somatic hybrids