MUTATION BREEDING IN CROP IMPROVEMENT

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MUTATION BREEDING IN CROP IMPROVEMENT DISCLAIMER: Copyright of some of the figures used from internet and different web sites is duly acknowledged. The copyright stands with its original developer. The information has been gathered here for educational purpose and not for any kind of commercial purpose.

Introduction : 

Introduction Mutation is a sudden heritable change in a characteristic of an organism Gene/Point mutation :- Mutation produced by changes in base sequence of genes . DISCLAIMER: Copyright of some of the figures used from internet and different web sites is duly acknowledged. The copyright stands with its original developer. The information has been gathered here for educational purpose and not for any kind of commercial purpose.

Introduction : 

Introduction Chromosomal mutation :- Mutation may be produced by changes in chromosome structure or even in chromosome number.

Mutation : 

Mutation If the mutation occurs in the junk DNA then it may have no consequence. If it occurs in the promotor region of a gene it may alter the regulation of the expression of that gene. If it occurs in the coding region of a gene it may affect the protein sequence. "junk" DNA is a provisional label for the portions of the DNA sequence of a chromosome or a genome for which no function has yet been identified. Scientists fully expect to find functions for some, but definitely not all, of this provisionally classified collection. About 80-90% of the human genome has been designated as "junk", including most sequences within introns and most intergenic DNA. While much of this sequence may be an evolutionary artifact that serves no present-day purpose, some is believed to function in ways that are not currently understood. DISCLAIMER: Copyright of some of the figures used from internet and different web sites is duly acknowledged. The copyright stands with its original developer. The information has been gathered here for educational purpose and not for any kind of commercial purpose.

Mutation : 

Mutation DISCLAIMER: Copyright of some of the figures used from internet and different web sites is duly acknowledged. The copyright stands with its original developer. The information has been gathered here for educational purpose and not for any kind of commercial purpose.

Point mutation : 

Point mutation No effect if the mutated codon -still codes for the same amino acid (see next slide) It can result in the protein having one different amino acid. The effect on protein function can vary from no effect to devastating diseases such as cycstic fibrosis. (see next slide) It can truncate the protein if the mutation results in a formation of a Stop codon (see next slide) Point mutations in the coding region of DNA can have one of three consequences:

Point mutations : 

Point mutations Three effects of point mutation Three effects of deletion and insertion

Mutant tomato harvested in kyoto : 

Mutant tomato harvested in kyoto A mutant tomato with a face resembling a Chinese lion mask was harvested from a field in the city of Yahata in Kyoto prefecture. The tomato is 3 times the normal size, measuring 10 cm in diameter and weighing 150 grams. The unusually long rainy season is believed to have caused the fruit to absorb too much moisture. The surprised farmer, who has been raising tomatoes for more than 30 years, says, “It’s the first time I’ve ever seen a tomato with a fully formed face.” DISCLAIMER: Copyright of some of the figures used from internet and different web sites is duly acknowledged. The copyright stands with its original developer. The information has been gathered here for educational purpose and not for any kind of commercial purpose.

Chromosomal mutant lion : 

Chromosomal mutant lion Veterinarians are engrossed in conducting an operation on a white lion at a pet veterinary hospital in Hangzhou, capital of east China's Zhejiang Province, Feb. 28, 2006. The 1.5-year-old male white lion with a weight of over 100 kilograms belongs to a rare species out of chromosome mutation, and was bred by the Hangzhou Wild Animals World. The veterinarians succeeded in taking out a tumor from the lion's front left leg's elbow during the operation. DISCLAIMER: Copyright of some of the figures used from internet and different web sites is duly acknowledged. The copyright stands with its original developer. The information has been gathered here for educational purpose and not for any kind of commercial purpose.

Effects Of Mutation : 

Effects Of Mutation Lethal :- They kill each & every individual that carry them in appropriate genotype . Dominant lethal : It can’t survive. Recessive lethal : kill in homozygous state. Sub Lethal & Sub Vital :- Both mutation reduce viability but don’t kill all the individual carrying them in appropriate genotype. Sub Lethal : Kill more then 50%. Sub Vital : Kill less then 50%. Vital :- a) Don’t reduce the viability. b) Crop improvement can utilize only such mutations. Lethal , Sub lethal & Sub vital mutations have no value in crop improvement.

MUTAGENS : 

MUTAGENS

Procedure for mutation breeding : 

Procedure for mutation breeding Mutagenesis :- Treating a biological material with a mutagen in order to induce mutation. Irradiation :- Exposure of biological material to one of the radiation(X-rays, gamma rays etc.). When mutations are induced for crop improvement, the entire operation of the induction & isolation etc. of mutants is termed as mutation breeding.

Selection of the variety for mutagen treatment : 

Selection of the variety for mutagen treatment Generally the variety selected for mutagenesis should be the best variety available in the crop. Note : In certain situations, it may be desirable to isolate in varieties other than the best one, ex. Dwarf & semi dwarf mutants would have to be isolated from tall varieties in cereal crops (wheat, rice etc.)

Part of the plant to be treated : 

Part of the plant to be treated Seeds, pollen grains, buds/cuttings or complete plant can be used for mutagenesis. It depends on whether the crop is sexually or asexually propagated & on the mutagen to be used. Sexually propagated crops : Seeds are commonly used because seed can tolerate extreme environmental conditions.

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Pollen grains are also infrequently used because :- They are difficult to collect in large quantities . Hand pollination(with treated pollens) is rather difficult. Survival percentage of pollens is relatively low. Note:- Pollen grains are the only plant part which can be treated with ultra violet rays.

Dose of the mutagen : 

Dose of the mutagen Clonal crops : Buds/cuttings are used for mutagenesis. The usefulness of a mutagen and its efficiency depends on the mutagenic agent employed as well as on specific characteristics of the biological system to be treated. An optimum dose is the one which produce the maximum frequency of mutation causes minimum killing. LD50 dose should be optimum.

Giving mutagen treatment : 

Giving mutagen treatment The plant part is exposed to the desired mutagen dose. In irradiation the plant parts are immediately planted to raise M1 plants from them. In case of chemical mutagens seeds are usually soaked for few hours to initiate metabolic activities. Then they are washed under running tap water. After this they are planted in the field to raise M1 generation.

Handling of mutagenic population : 

Handling of mutagenic population Treatment of seeds & vegetative propagules commonly produce chimeras. Shoot tip meristem has three layers :- L1 :- Give rise to epidermis. L2 :- Part of leaf mesophyll & gametes. L3 :- Yield the rest of plant. Periclinal chimera :- When the whole of L1 , L2 or L3 layer is affected. Sectorial chimera :- When only a part of L1 , L2 or L3 layer is affected .

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In sexually reproducing species L2 chimera will be transmitted to the next generation. In sexually reproducing crops mutation breeding utilize both recessive & dominant mutations.

Application of mutation breeding : 

Application of mutation breeding Induction of desirable mutant alleles which may not be present in the germplasm available to the breeder. In improving specific characteristics of well adapted high yielding variety . Mutagenesis has been successfully used to improve various quantitative characters including yield.

Limitations : 

Limitations The frequency of desirable mutants is very low. Desirable mutations are commonly associated with undesirable side effects. There may be problems in the registrations of a mutant variety. Mutations in quantitative traits are usually in the direction away from the selection history of the parent variety. Most of the mutations are recessive.

List of some varieties developed in india through mutation breeding : 

List of some varieties developed in india through mutation breeding

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DISCLAIMER: Copyright of some of the figures used from internet and different web sites is duly acknowledged. The copyright stands with its original developer. The information has been gathered here for educational purpose and not for any kind of commercial purpose.

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DISCLAIMER: Copyright of some of the figures used from internet and different web sites is duly acknowledged. The copyright stands with its original developer. The information has been gathered here for educational purpose and not for any kind of commercial purpose.

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DISCLAIMER: Copyright of some of the figures used from internet and different web sites is duly acknowledged. The copyright stands with its original developer. The information has been gathered here for educational purpose and not for any kind of commercial purpose.

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THANKS