Mutation breeding

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Mutation breeding:

Mutation breeding By: A.Sri Dhanya DAG 01

Introduction :

Introduction Mutation refers to sudden heritable change in the phenotype of an individual. In the molecular terms, mutation is defined as permanent and relatively rare change in the number or sequence of nucleotides. Mutations arise due to change in DNA bases The change in the nucleotide may involve replacement of one pyramidine by another pyramidine or one purine by another purine known as Transition. Sometimes change in the nucleotides involves substitution of a purine by pyramidine or vise versa called as transversion.

Types of mutations:

Types of mutations Macro mutations Mutations with distinct morphological changes in the phenotypes Found in qualitative characters and also called as oleigenic mutations. Easy to identify. Micro mutations Mutations with invisible phenotypic changes. Found in qualitative characters and are also called as polygenic mutations. Difficult to identify. They are of economic importance in plant breeding They are of two types Spontaneous(occurs in nature) and Induced (artificially induced by various mutagenic agents). Induced mutations are of two types 1. macro mutations and 2. micro mutations

Situations for mutation breeding::

Situations for mutation breeding: When desired variety is not found in cultivated varieties. When a high yielding variety has oliegenic defect. When there is a light linkage between desirable and undesirable characters. When in fruit crop, the improvement has to be made without change in the taste and color of fruits When a particular reaction is to blocked. In those crops, where generation cycle is very long. When attractive flower and foliage to be developed in ornamental plants.

PowerPoint Presentation:

With and with out seeds (after mutation breeding)

Types on mutagens:

Types on mutagens Physical mutagens Chemical mutagens

Physical mutagens:

Physical mutagens X-rays: they are sparsely ionizing and non particulate. Induce mutations by forming free radical and ions. Cause addition, deletions, transitions and transversions. Gamma rays: sparsely ionizing, non particulates and penetrating. Induce mutations by ejecting atoms from the tissues. Cause addition, deletions, transitions and transversions Alpha rays: densely ionizing, particulate less penetrating and positively charged. Act by ionization and excitation. Cause chromosomal and gene mutations.

Physical mutagens:

Physical mutagens Beta rays particles: sparsely inonizing, particulate, more penetrating than alpha particle and negatively charged. Act by ionization and excitation. Cause chromosal and gene mutations. Fast and thermal neutrons: densely ionizing, particulate, neutral particles highly penetrating. Cause chromosomal breakage and gene mutations. Ultra violet rays: non ionizing and low penetrating. Cause chromosomal breakage and gene mutations.

Chemical mutagens:

Chemical mutagens Alkylating agents: ethyl methane sulphonate( AT GC transitions ) , methly methane sulphonate(transitions), ethly ethane sulphonate(GC AT transitions ), ethylene imines(transitions). Base analogues: 5-bromo uracil(AT GC ), 2- amino purine(AT GC ) Acridine dyes: acriflavin and proflavin (deletion, addition and frame shift). Others: nitrous acid(AT GC ), hydroxylamine(GC AT ),sodium azide(transitions).

procedure::

procedure: Choice of mutagen (X rays, gamma rays, UV rays, EMS, MMS, EI, etc) Mutagenic treatment (giving mutation dose to the selected part) Handling treated material (handling mutagen treated material) Choice of material (the crop to be mutated)

PowerPoint Presentation:

Mutation in wheat

Applications in crop improvement::

Applications in crop improvement: Development of improved varieties. Induction of male sterility. Production of haploids. Creation of genetic variability. Over coming self incompatibility. Improvement in adaptation.

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