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
Mutation is a sudden heritable change in a characteristic of an
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
Mutations are random i.e ., 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
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
II.) BASED ON QUALITY
(A) Structural Mutation: Changes in the nucleotide
content of the gene.
Substitution mutation – Substitution of one nucleotide for
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
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
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
• 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
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.
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
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′-
e.g., Nitrous acid, Hydroxyl amine, Sodium azide*.
(* denotes that these agents are commonly used in mutation
24. 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,
• In India Gamma garden was 1st started in Bose Research
Institute, Culcutta in 1959.
25. 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.
26. 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.
27. Primary research center and Institutes in India that
participated in the development and release of various
Indian Agricultural Research Institute ( IARI) - New Delhi
Baba Atomic Research Center - Mumbai
Tamil Nadu Agricultural University - Tamil Nadu
National Botanical Research Institute - Lucknow , UP