mutation and its application on crop improvement
Types of mutation
Achievements of mutation breeding
Advantages of mutation
Limitations of mutation breeding
Mutation refers to sudden heritable change in the phenotype of an individual.
Is the change in genetic material : a random change in a gene or chromosome resulting in new trait.
The term mutation breeding was first coined by freisleben and lein (1994).
Father of mutation breeding -Ake gustafson.
It is most commonly used in asexually propagated crop and self pollinated crops.
TYPES OF MUTATION
A. Spontaneous mutations: mutation occur in natural populations.
B .Induced mutations: mutation may be artificially induced by various mutagenic agents.
Induced mutations are two types:
- Macro mutation : mutation with distinct morphological changes in the phenotype.
- Micro-mutations: mutation with invisible phenotypic changes.
- Produce a large phenotypic effect.
2.Oligogenic in nature.
3.Easily identify on individual plant basis.
4.Can be easily selected in m2 generation
1.Produce a small phenotypic effect.
2.Poligenic in nature.
3.Cannot be identify on individual plat basis.
4.Selection delays till m3
Mutagens: physical or chemical agent which greatly enhance the frequency of mutation.
Type of mutagen :-
A) Physical mutagens-
E.g. – lonising radiation :
(a)Particulate radiations: alpha-rays, beta-rays ,fast netrons and thermal netrons.
(b) Non-particulate radiations : x-rays and gamma rays.
2)Non ionising radiation : ultraviolet radiation.
1.Alkylating agents:EMS (ethyl methane sulphonste), MMS , sulphur mustard, nitrogen mustard.
2.Acridine dyes: proflavin, acridine orange, acridine yellow and ethidium bromide.
3.Other mutagens: nitrous acid ,sodium ozide.
Inducing desirable mutation and exploiting them for crop improvement. It is commonly used in self pollinated crops and used to produce traits in crops such as larger seed ,new colour .
Important steps to know before mutation breeding
1) selection of variety for mutation breeding,
It should be the best variety available in crop and seed should be pure.
2) Part of the plant to be treated
3) Dose of the mutagen :- Mutagen generally induce a high frequency of chromosomal change and meiotic and mitotic irregularities, optimum mutagen does is one, which produce maximum frequency of mutation and causes the minimum killing.
- Higher yield barley (DL 253),Pea (Hans),groundnut (Co 2,TG 17).
- Short stature barley (RDB 1),Rice (Prabhawati).
- Earliness rice (IIT 48,IIT 60,Indira,Padmini).
- Stress resistance salt tolerance in rice(Mohan).
- Water logging tolerance in jute (Padma).
- Bold seed size groundnut (PB 1,PB 2, vikram) and Rice (jagannath).
- Sugarcane(S. Officinarum) Co 8152 is a gamma –rays induced mutant from Co527,it gives 40% higher cane yield than the parent variety .
- Low frequency of the desired mutation.Pleiotropic effect(one gene expressing two or more unrelated effects.Most of the mutations are recessive.Identification of micro mutation is very difficult.
Health risks :handling, chemical mutagens, fast neutrons treatments.
Mutants can have strong negative pleiotropic effect on other traits.
- Mutation breeding is a cheap and rapid method of developing new varieties.
- Induction of desirable mutant allele, which is not present in germplasm.
- Limited breeding effort required.
- Novel variation can be produced.
- Mutation breeding is the simple, quick and the best way when a new character is to be induced.
Mutation breeding has long been a beneficial tool in not only the plant breeder’s tool box, but also basic geneticist’s. In crops where diversity for a given trait is low or non-existent, induced mutagenesis provides an avenue of possibility. With a clear objective, efficient mutagenic protocol, and a high throughput and efficient phenotypic screening method, mutagenesis can be of great benefit for the improvement of crop plants.
Plant Breeding- B.D. Singh
Plant Mutation Breeding and Biotechnology- Q.Y. Shu, B.P. Forster, H. Nakagawa
Mutagenesis- Rajnikant Mishra
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