Mutation - History Mutation Characters Classification Mutagens - Types Mutation breeding Steps Gamma garden Achievements

1. DEPARTMENT OF GENETICS &
PLANT BREEDING
FACULTY OF AGRICULTURE
ANNAMALAI UNIVERSITY
GPB 502 PRINCIPLES OF PLANT
BREEDING
MUTATION BREEDING
Presentation by
P.KATHIRAVAN
M.Sc.,(Agri) Genetics and Plant Breeding

2. • HISTORY OF MUTATION
• 1929- First proof of induced mutations in plants ; radium ray treatment of
Datura stromanium (Gager and Blakeslee).
• 1927 – H.J.Muller working with Drosophila provides proof of mutation
induced by x-rays, Muller champains induced mutation for animal and
plant breeding and opens a new era in genetics and breeding..

3. • 1928 – Stadler publishes the first result of mutation induction in crop
plants, barley , wheat, maize ,oats etc.,
• 1936- The first induced mutant variety is released ,tobacco variety –
‘chlorina’using x-rays in Indonesia .
• 1944- First reports of chemical induced mutation by Auerbach and Robson.

4. MUTATION
• Mutation is a sudden heritable change in a characteristic of an organism.
• A mutation may be the result of a
 change in a gene,
 a change in chromosome(s)
 that involves several genes or
 a change in a plasma gene/
 genes present in the cytoplasm.
eg., In chloroplasts, mitochondria, etc.,

5. • Mutations have certain general characteristics (RRR)
• Mutations are generally recessive but dominant mutations also occur.
• Mutations are random ie ., they may occur in any gene. However, some
genes show higher mutation rates than others.
• Mutations are recurrent that is, the same mutation may occur again and
again.
• Induced mutations commonly show pleiotropy, often due to mutations in
closely linked genes.

6. • “PLEIOTROPY” refers to the phenomenon in which a single locus affects
two or more apparently unrelated phenotypic traits.

7. • Mutations are generally harmful to the organism. Most of the
mutations have deleterious effects, but a small proportion (Ca0.1%) of
them are beneficial.

8. • CLASSIFICATION OF MUTATION
• I) BASED ON SIZE
• 1.Point Mutation - A point mutation occurs in a genome when a single
base pair is added, deleted or changed (base pair substitution, insertion or
deletion).
• Frame shift mutation – It is due to deletion or insertion of a base
sequence, so that there will be a change in amino acid.

10. 2. Gross Mutation
• Changes involving more than one nucleotide pair, may involve the entire
gene, the entire chromosome, or sets of chromosomes (polyploidy).
• II.) BASED ON QUALITY
• (A) Structural Mutation: Changes in the nucleotide content of the
gene.
• Substitution mutation – Substitution of one nucleotide for another.

11. • a. Transition mutation substitute one purine for another or one pyrimidine
for another.
• b. Transversion mutation substitute a purine for a pyrimidine or vice versa.
• (B) Rearrangement Mutation:
• Changing the location of a gene within the genome often leads to “position
effects”.

12. • 1. Within a gene
• Two mutations within the same functional gene can produce different
effects, depending on whether they occur in the cis or trans position.
• 2. Moving the gene locus
• It may create new phenotypes, especially when the gene is relocated near
heterochromatin.

13. • a. Translocation – movement to a non-homologous chromosome.
• b. Inversion – a portion of the DNA sequence is excised then reinserted at
the same position but in the opposite orientation.
• III. BASED ON ORIGIN
• (A) Spontaneous mutation: Occurs naturally and is of unknown origin. It
is also known as background mutation. It occurs at a frequency of 10-6 .

14. • (B) Genetic control: The mutability of some genes is known to be
influenced by other ‘mutator genes’.
• 1. Specific mutator – It affects one locus.
• 2. Nonspecific mutator – It simultaneously affects many loci.
• (C) Induced mutation: Mutations produced due to the treatment with
either a chemical or a physical agent are called as induced mutation.

15. • The agents capable of inducing mutations are known as mutagens.
• Mutation induction rarely produces new alleles; it produces alleles, which
are already.
• known to occur spontaneously or may be discovered if an extensive search
were made.
• It is reasonable to say that induced mutations are comparable to
spontaneous mutations in their effects and in the variability they produce.

16. • But the induced mutations have a great advantage over the spontaneous
ones; they occur at a relatively higher frequency so that it is practical to
work with them.
• Mutagens
• Agents that induce mutations are known as mutagens.
• Mutagens may be different kinds of radiation (physical mutagens) or
certain chemicals (chemical mutagens).

17. TYPES OF MUTAGENS:
• A. Physical mutagens
(all of them are various kinds of radiation) .
• 1. Ionizing radiation
a. Particulate radiation.
• eg. α – rays (DI), β- rays (SI), fast neutrons* (DI), and thermal
neutrons (DI).

19. b. Non Particulate radiation
(electromagnetic radiation),
• eg., X- rays* (SI), and γ- rays (SI).
• DI - densely ionizing
• SI - sparsely ionizing radiations.
• 2. Non Ionizing radiation.
• eg. UV radiation.

20. • B. Chemical mutagens
• 1. Alkylating agents
• e.g., Sulphur mustard, Nitrogen mustards,
• Epoxides, Imines, (e.g, ethylene imine or EI)*,
• Sulphates and sulphonates, Diazoalkanes,
• Nitroso compounds, e.g., N-methyl-N-nitro-N′-
nitrosoguanidine (MNNG)

22. • 2. Acridine dyes
• e.g., Acriflavine, Proflavine ,
• Acridine orange, Acridine yellow,
• Ethidium bromide.
• 3. Base analogues
• e.g., 5- bromouracil, 5-chlorouracil.

23. • 4.others
• e.g., Nitrous acid, Hydroxyl amine, Sodium azide*.
• (* denotes that these agents are commonly used in mutation breeding).

24. • MUTARION BREEDING
• Inducing desirable mutation and exploiting them for crop improvement.
• It commonly is in self pollinated crops and used to produce traits in crops
such as larger seeds, new colour, greater yields etc.

26. • Important steps to know before mutation breeding are:
• Selection of variety for mutation breeding.
It should be the best variety available in crop and Seed should be pure.
• Parts of plants to be treated .
Seed, pollen grains, vegetative propagules or even complete plant plants
may be used for mutation treatment.

27. • Dose of mutagen :
• Mutagens generally induce a high frequency of chromosomal changes and
meiotic and mitotic irregularities,
• optimum mutagen dose is one, which produces maximum frequency of
mutations and causes the minimum killing.
• LD50 :
• It is the dose of mutagen which kills 50% of the treated individual.
• It varies with crop to crop.

29. MUTATION BREEDING FOR
POLYGENIC TRAITS

31. MUTATION BREEDIG FOR
OLIGOGENIC TRAITS

33. • SCREENING AND SELECTION
• Mainly three types screening /selection techniques are used in M2 and
subsequent generation.
• Visual: most effective and efficient method for identifying mutant
phenotypes.
• Mechanical/Physical: Very efficient for seed size ,shape, weight, density,
etc., using appropriate sieving machinery.

34. • Other methods :
• Low alkaloid content mutants can be selected using colorimetric test
(method of determining the concentration of a chemical element or
chemical compound in a solution with the aid of a colour reagent),
chromatographic or electrophoresis techniques may be used to select
isolate protein varients.

37. GAMMA GARDEN
• Gamma garden or Atomic garden is a concept popularized after the Word
War 2 for the peaceful use of atomic energy (atoms for peace) for the crop
improvement.
• Gamma gardens are first started in Long Island, New York, USA.
• In India Gamma garden was 1st started in Bose Research Institute,
Culcutta in 1959.

38. • Gamma gardens or Atomic gardens are a type of induced mutation
breeding where radioactive sources particularly gamma rays from cobalt -
60 or Caesium-137 are used to induce desirable mutations in crop plants.

39. • Former Atomic Gardening Society President Muriel Howorth shows
popular garden writer Beverley Nichols a two-foot-high peanut plant
grown from an irradiated nut in
her own backyard.

40. • Applications of Mutation Breeding.
• Induction of desirable mutant alleles which may not be available in the
germplasm.
• It is useful in improving specific characteristics of a well adapted high
yielding variety.
• Mutagenesis has been successfully used to improve various quantitative
characters including yield.

41. • F1hybrids genetic variability by inducing mutation and to facilitate
recombination of linked genes.
• Irradiation of interspecific (distant) hybrids has been done to produce
translocations hybrids from intervarietal crosses may be treated with
mutagens in order to increase.

42. • Advantages of mutation breeding:
• Mutation breeding is a cheap and rapid method of developing new
varieties.
• Induced mutagens are used for the induction of CMS (Cytoplasmic male
sterility).
• Ethidium Bromide (EB) has been used for induction of CMS in barley.

43. • Mutation breeding is more effective for the improvement of oligogenic
character (a trait that is influenced by a few genes).
• Mutation breeding is simple, quick and the best way when a new character
is to be induced.

44. • Disadvantages
• The process is generally random on unpredictable.
• Useful mutants are rare and predominantly recessive.
• Health risk: Due to handling of chemical mutagens and physical
mutagens such as radiations fast neutrons treatment
• Most mutants are of no use to breeding even if a large number of mutants
can be produced.

45. • Field trailling and germplasm storage can be expensive and require a lot
of space and careful management if large mutant populations are handled.

46. • Primary research center and Institutes in India that participated in
the development and release of various mutants;
• Indian Agricultural Research Institute ( IARI) - New Delhi
• Baba Atomic Research Center - Mumbai
• Tamil Nadu Agricultural University - Tamil Nadu
• National Botanical Research Institute - Lucknow , UP

47. • Achievements of mutation breeding
• High yield barley (DL 253), Pea (Hans),
• Groundnut (Co 2, TG 17)
• Short stature barley (RDB 1),Rice (Prabhavathi)
• Earliness Rice (IIT 48,IIT 60,Indira, Padmini)
• Stress resistance ,Salt tolerance in Rice (Mohan)
• Bold seed size Groundnut (PB 1,PB 2,Vikram) and Rice (Jagannath).