1. MUTATION BREEDING BY BHANUPRIYA R CLASS NO.212 111 DC BOTANY

2. WHAT IS MUTATION BREEDING?  Mutation is the change in genetic material or a random change in gene or chromosome resulting in a new trait.  Mutation breeding was first initiated by L.J.Stadler in 1928 in plants for the purpose of crop improvement.  Two types of mutation : spontaneous and induced mutations  The utilisation of induced mutation for crop improvement is known as mutation breeding.  Mutation can be induced artificially by a) physical agents :x-rays,uv rays etc. b)chemical agents : nitrous acid,malic hydrazine,EMS etc.  The agents used for producing them are termed as mutagens

3.  Induced mutation are of two types:  Macromutation  Micromutation  A macromutation produces a large phenotypic effect recognizable on individual plants.  In contrast, a micromutation has small phenotypic effect that cannot be recognised on individual plants.

4. TYPES OF MUTATION Based on: DIRECTION - 1)Forward 2)Reverse Mutation TISSUE - 1)Somatic 2)Germinal SITES - 1)Nuclear 2)Cytoplasmic mutations CHARACTER- 1)Morphological 2)Biochemical VISIBILITY - 1)Macromutation 2)Micromutation SOURCE - 1)Spontaneous 2)Induced

5. INDUCED MUTATION BY RADIATIONS  Electromagnetic waves travelling at a high speed through a space is called radiations or rays  The treatment of plant materials with physical radiations to induce mutations is called irradiation.  Irradiation method of plant breeding is also known as radiation breeding.  The radiation used in plant breeding are of two types: - ionizing radiations -Non- ionizing radiations

6. IONISING RADIATION Radiations that on striking, converts the atom into ions are called ionising radiations. Sl. no Type of radiation Main PropertiesMode of action or changes caused 1X-raysPenetrating and non particulate Induce mutation by forming free radicals and ions. cause addition, deletion and transition. 2Gamma raysVery penetrating and non particulate Induce mutations by ejecting atoms from the tissues. cause addition,deletion and transitions 3Alpha particles Particulate,less penetrating and positively charged. Act by ionisation and excitation. Cause chromosomal and gene mutation. 4Fast and thermal neutrons Particulate,neutral particles,highly penetrating. Cause chromosomal breakage and gene mutations. 5UV raysNon ionizing and low penetrating. Cause chromosomal breakage and gene mutations.

7. STEPS IN MUTATION BREEDING  Objectives of programme  Selection of variety  Plant part treated  Dose of mutagen(LD 50)  Giving mutagen treatment: - irradiation- immediately planted to raise M1 -chemicals - seeds are presoaked and exposed to desired mutagen.  Handling of mutagen treated population.  Yield trials  Release of a variety

8. PROCEDURE OF MUTATION BREEDING  Treating a biological material with a mutagen in order to induce mutations is known as mutagenesis. Mutation breeding process consists of following steps : 1)Objective of programme: it should have well defined and clear cut objectives 2)Choice of material: The best adopted variety of a crop should be chosen for mutagenesis, because such variety has all acceptable agronomic features. 3)Plant part to be treated :  seeds,pollen,vegetative propagules, sometimes complete plant as treated with mutagen.  The selection of plant part varies with crop plant.  Seeds are the best part in sexually propagating plants.

9. 4) Dose of mutagen: The mutagen treatment reduces germination,growth rate and fertility of organism. Damages increases with increase in the dose mutagen and duration of exposure. Optimum dose of mutagen is expressed as LD50. LD50 refers to a dose of mutagen that kills 50% of the treated individuals. The dose of treatment depends on the intensity of radiations or concentration of chemical mutagens. An optimum dose is the one which produces the maximum frequency of mutations and cause minimum killing. Dose close to LD50 should be the optimum. 5)GIVING MUTAGEN TRATMENT: - X-ray irradiation is given in X-ray room. - Gamma ray irradiation is given in gamma garden. - Neutron treatment is given from neutron flush coming from generator. - Beta rays treatment is given in the Radioisotope Laboratories.

10. X- ray machine Neutron generator

11. 6) Handling of mutagen treated population Treatment of seeds and vegetative propagules commonly produces chimeras A chimera is an individual with one genotype in some of its parts and another genotype in the others. One or more clonal or sexual generations with selection are necessary for stable mutant phenotype. Mutant alleles are generally recessive.Dominant mutation can occur, however, the chance of dominant mutation is very less.

12. Steps involved in irradiation of plant breeding

13. ADVANTAGES OF MUTATION BREEDING  Artificial mutations induce sufficient variability in plants to induce improved crop varieties.  Mutation breeding takes less time than conventional breeding methods.  It needs minimum land and labour to produce improved varieties.  Mutation breeding can be adopted for self pollinated,cross pollinated and vegetatively propagated crops.  Improve morphological, physiological characters, disease resistance and quantitative characters including yielding ability.

14. LIMINATIONS OF MUTATION BREEDING  Frequency of desirable mutations is very low.  Only a few institutions have the facilities to conduct mutation breeding.  For each and every step of mutation breeding financial assistance of the Government is necessary.  Identification of micro mutation is difficult.  Pleiotropic effect (one gene expressing two or more unrelated effects).

15. REFERENCES  Shukla,R.S., Chandel,P.S. 1974.CYTOGENETICS EVOLUTION AND PLANT BREEDING. S Chand and Company Ltd.  Sasidharan,A., Valsalakumar,N. 1989. A TEXTBOOK OF BOTANY.Vidyarthi mithram press and book dept.Kottayam.  Singh,B.D.1999. PLANT BREEDING PRINCIPLES AND METHODS.kalyani publishers,New delhi.  Kumerasan,V.2014. HORTICULTURE AND PLANT BREEDING.Saras publication.Nagercoil.

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