mutation breeding

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WELCOME TO THE PRESENTATION
ON
Mutation Breeding Techniques
for Crop Variety Development
Dr. M. A. Malek
Director (Research)

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Importance of developing new crop
varieties
 To feed the increasing population from the
decreasing cultivable land facing unfavorable
climatic conditions;

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Growing Population
 By 2041, the population of
Bangladesh will reach 220 million,
35% higher than today.
 In order to feed this increasing
population, food production must
increase proportionately.

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 Develop more tolerant varieties
to face drought, salinity, flood,
temperature (high or low) etc.;

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i. Genetic impurity due to poor maintenance of
the varieties,
ii. Becoming susceptible to diseases and insect-
pests due to the development of virulent
races/biotypes of pathogens/insect-pests,
iii. Natural mutations
Varietal deterioration:

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 Germplasm collection;
 Plant introduction;
 Hybridization;
 Induced mutation;
 Polyploidization;
 Creation of somaclonal variation
through tissue culture; and
 Genetic engineering.
Different plant breeding methods for
crop varieties development and mutation
breeding is one of them.
How can we get genetic variation?

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Plant Breeding deals with changing the genotype
of plants to be more useful to humans.
In true sense, plant breeding has been
practiced since near the beginning of
human civilization.
So, any plant breeding program aims to
develop plant varieties superior to existing
ones in yielding ability or any other
desirable traits.

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 Higher yield;
 Early maturity;
 Improved quality for consumers preference;
 Tolerance/resistance to biotic factors to
ensure yield loss;
 Tolerance to abiotic factors to bring non-
cultivable land under cultivation;
 Shattering resistance to reduce yield loss;
Some major objectives of plant variety
development:

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 Synchronous maturity for easier harvest and
lowering the production cost;
 Improving agronomic characteristics like plant
height, branching, erect or trailing habit;
 Lodging resistance to avoid risk of yield loss;
 Photo-insensitivity for growing round the
year;
 Thermo-insensitivity for growing under
low/high temperature;
Contd.

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i. Presence of genetic variation and
ii. Selection
Two basic requirements of Plant Breeding:

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Plant breeding requires genetic variation
of useful traits for crop improvement.
Therefore, in any breeding program,
creation of genetic variation is always
the first step.

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Induced mutation has become a
proven way of creating variations
within a crop variety.

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Selection is the next/second step in crop
improvement.
It involves the identification and isolation of
desirable plants having desirable combinations of
characters depending on breeding objectives.
Selection is mainly based on phenotype and
finally results in an improved line or variety.

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 Mutation can modify an existing gene
in the plant to create a new allele.
 Can produce any trait of interest:
morphotype, yielding, resistance/
tolerance to abiotic and biotic,
nutritional quality,..

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Mutation: Mutation is the changes in genetic
material i.e., a random change in gene or
chromosome resulting in new trait(s).
Mutations: 2 types
Spontaneous mutation: Occurs spontaneously in
nature due to environmental effects.
Induced mutation: Induced artificially.

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When mutations are artificially induced
for crop improvement, the entire
operation of the mutation induction and
isolation of desirable mutants is termed
as mutation breeding.

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In short, mutation breeding is the
process to generate mutants with
desirable trait(s).
And compared to conventional breeding
methods, mutation breeding saves
time to develop a new crop variety.

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From 1930–2015 more than 3,200
mutant varieties have been released
worldwide for commercial use in more
than 210 plant species from over 70
countries.
Bangladesh contributed only 1.4% (as
on 2011).

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Most of the mutant varieties
(89%) have been developed using
physical mutagens and with
gamma rays alone accounting for
the development of 60%.

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1. Objective of the mutation breeding program,
2. Selection of the variety for mutagen treatment,
3. Part of the plant to be treated,
4. Dose of the mutagen,
5. Giving mutagen treatment, and
6. Handling of the mutagen treated population.
PROCEDURE/STEPS FOR MUTATION BREEDING

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A mutation breeding should have a
well defined and clear-cut objective.
1. Objective of the program

Common targets are:
1. To improve one or a few specific traits of a preferred
variety or an elite line;
2. To induce a morphological marker (colour, awns,
bracts, hairiness, etc.) in order to establish distinctness
in a promising line to make it easy to identify and meet
the requirement for variety registration; and/or
3. To induce male sterility or fertility restoration making a
line useful as a component for hybrid variety
production.

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Generally, the variety selected for the
mutagenesis should be the best variety
available in the crop, and has a specific
limitation.
2. Selection of variety for
mutagen treatment

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Mainly seeds are used for
mutagenesis in oilseeds, but pollen
grains, cutting, bulb, rhizome etc.
can also be used.
3. Part of the plant to be treated

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A dose close to LD50 should be the optimum which
produces maximum mutations and causes minimum
killing.
Normally with sparsely ionizing radiation like X-
ray and Gamma ray the selected dose will cause
30-50% reduction in seedling growth in laboratory
test.
LD50 varies with the crop species and with the
mutagen used.
4. Dose of the mutagen

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A preliminary experiment is generally
conducted to determine the suitable
mutagen dose.

14 days-old soybean seedlings from irradiated seeds

14 days-old seedlings from irradiated seeds with gamma rays
BRAGG MTD-451

Seedling from irradiated mustard seeds
by gamma rays after germination

Seedlings from irradiated seeds of
Binasarisha-7 by gamma ray

Seedlings from irradiated seeds of
SAFAL by X-ray

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5. Giving mutagen treatment
The selected plant parts are exposed to the
desired mutagen dose.
In case of irradiation, dry seeds, bud, rhizome,
cutting or sucker are exposed to the desired
radiation dose and then immediately planted to
raise M1 plants.
Irradiated pollen grains are used for pollination.

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- Seeds are presoaked for a few hours to
initiate metabolic activities and
- Then exposed to the desired concentration of
mutagen and
- Then washed in running tap water for about
four hours to remove the mutagen present in
the seeds.
- The treated seeds are immediately planted in
the field to grow M1 generation.
In case of chemical mutagens-

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6. Handling of the mutagen treated population
i. e., selection in subsequent generations

Sowing of M1 seeds
Considering the detrimental effects of mutagens
on seed viability, the M1 must be handled with
more care than untreated controls. The M1
should therefore, be grown:
 Greenhouse conditions;
 Field conditions;
 Time of sowing M1;
 Condition of the treated M1 seeds;
 Density of sowing; and
 Weed control.

Greenhouse conditions
• If possible the M1 should be grown in a greenhouse
where careful attention can be paid with respect to
watering, fertilizer provision, lighting and
temperature, weed, pest and disease control to
maximize plant survival and production of the next
generation. Isolation of the M1 population is also
easier in the greenhouse, thus limiting pollination
from external sources, which could bring in
unwanted (non-mutant) variation.
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Field conditions
• If greenhouse conditions are not available
or are not affordable, then field conditions
can be used.
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Time of sowing M1
• The M1 material will develop optimally if sown during
the season when the climate is best for early
seedling and plant development and weed control is
less of a problem.
• However, slightly later sowing (2 or 3 weeks) may
help reduce tillering and may improve the conditions
for isolation against cross-pollination.
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1. Inhibition or delaying in germination;
2. Reduction in auxin content;
3. Inhibition of mitosis;
4. Reduction in growth of root and shoot;
5. Decreasing in the number of plant
surviving to maturity;
6. Lower pollen fertility as indicated by
lower or no seed set.
The abnormalities observed in M1

Some important characteristics to be considered
during selection
Characteristics for higher seed yield -
 Number of plant accommodation per unit area,
 Number of panicle/pods/capsules per plant,
 Number of seeds/panicle/pods/capsule or pod, and
 1000-seed weight.

Characteristics for drought tolerance:
 Rapid uptake of soil moisture,
 Conservation of water in plant tissues,
 Rapid root growth,
 Extensive,well developed and deep root system,
 High photosynthetic efficiency,
 Sensitive stomata to moisture deficit,
 Maintenance of high turgor pressure and
 Early flowering and early maturity.

Characteristics for salinity tolerant lines
 Less Na uptake in comparison to K
 Less total bio-mass reduction
External symptoms of susceptible lines
 Leaf senescence from top to bottom
 Sterility of flowers
 Reduced root growth

Disease resistance:
Ability of a host strain to restrict or
even prevent the production of diseases
symptom by a pathogen.
Disease tolerance:
Ability of a host strain to avoid or
minimize loss in productivity although it
has been infected by a pathogen.

Figure: Screening for salinity tolerance, in hydroponic nutrient solution, of rice
mutants at four levels of salt (NaCl2) (0, 5, 10 and 15 dS/m) showing
variation in shoot and root growth after 14 days of applied stress
0 dS/m 5 dS/m 10 dS/m 15 dS/m
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Figure: Screening lentil mutants, in hydroponic solution, for drought
tolerance using PEG6000 at four levels of concentrations (A, B, C and
D), respectively: 0, 10, 15 and 20%.
A
D
B
C
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Treating seeds with mutagen
M1
i) Mutagen treated M1 seeds are close-planted
ii) Seeds from individual plant harvested separately
M2
i) Individual plant progenies grown
ii) Plants from rows containing or suspected to contain
the mutant alleles
or
Fertile and normal looking plants harvested separately
M3
i) Selected individual plant progenies grown
ii) Superior lines harvested in bulk, if they are homogenous
iii) In heterogygous progenies, individual plants are selected
lnduced mutation followed by selection

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M4
i) Individual plant progenies from the selected plants grown
ii) Superior homogenous mutant lines harvested in bulk
iii) Segregating lines usually rejected
M5
i) PYT with a suitable check
ii) Superior mutant lines are selected
M6- M8
i) RYT/ ZYT and On-station & On-farm yield trials with a
suitable check at several locations for 2/3 years
ii) Outstanding mutant lines released/registered as varieties

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After completion of the above trials,
application is to be done to the National
Seed Board (NSB) of Ministry of
Agriculture (MoA) for registration as
variety(s) of superior line(s) of non-
notified crops in a prescribed form.

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To
Member secretary,
National Seed Board and Director General (Seed)
Ministry of Agriculture, Bangladesh Secretariat, Dhaka
Name and address of seed dealer (with registration number):
Name of Crop (Botanical name):
Name of crop (English name):
Bengali name of crop:
Name proposed for registration:
Origin of the variety:
Name of breeder:
List the main characteristics of the variety mentioning the
character(s) which make the variety different from other
varieties:
Application form for registration of variety of non-notified crops

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Ecological requirement:
Season:
Soil:
Water:
Any other information:
Cultural requirements:
Method of cultivation:
Seed rate per ha:
Period (in days) from sowing to harvest:
Remarks about susceptibility to disease and insect-
pest:
(a) Results of yield trials:
(b) Yield potential (t/ha):
Signature of Applicant
(Seal)

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Chairman : Additional Director
(Regional office), DAE
Member Secretary: Regional Field Officer
(RFO) of SCA
Members : Representatives of NARS
Institute and DAE
Field Evaluation Team for 5-6 regions

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National Technical Committee
Chairman : Executive Chairman, BARC
Member Secretary : Director, SCA
Members : Representatives of NARS Institute
and DAE

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National Seed Board (NSB)
Chairman : Secretary, MoA
Member Secretary: Director General (Seed),
MoA
Members : DG/Director of NARS
Institutes and DAE and;
Farmer & NGO representatives

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Through transcription : DNA to mRNA
Through translation : mRNA to a polypeptide
chain/protein.
A gene is a segment of DNA & it acts
by synthesizing protein.
HOW?
In mRNA, there are 4 types of nucleotides namely
Uracil (U), Cytosine (C), Adenine (A) & Guanine (G).
Each group of three nucleotides (genetic code) is
responsible for a particular amino acid.

Mutation Result!!!!
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ab¨ev`

mutation breeding

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