Principles of Plant Breeding (2+1)

Introduction

Mutation Breeding

Intrduction
Mutation is a sudden heritable change in a characteristic of an organism. It is the results in gene changes in chromosome or in plasma gene.
Gene or point mutations.


• Mutation produced by changes in the base sequence of genes as a result of transition, transversion, deletion, duplication or inversion etc.

Chromosomal mutation


• Mutation produced by changes in chromosome structures and chromosomal numbers. Cytoplasm mutation is occurs in cytoplasmic genes.

History


• Term mutation was first introduced by Hugo de varies in the year 1900. The discovery of the mutagenic effects of X-rays on the fruit fly (Drosophila) by H. Muller in the 1920. And gamma rays and x-rays by L. J. Stadler, later Muller got Nobel Prize In 1946.
• Spontaneous mutation: Mutations occur in natural population at a 10 6 rate. The frequency of spontaneous mutation is one in 10 lakhs.
• Induced mutation: Mutation may be artificially induced by a treatment with certain physical or chemical agents. The chemicals used for producing them are termed as mutagens. The utilization of induced mutation for crop improvement is known as mutation breeding. Induced mutations are used more often in a supplementary role as a source of new alleles. However, it is still important in breeding vegetatively propagated species, including field crops, ornamentals, fruit and forest species. It is especially useful in ornamental plant breeding

Characteristics of mutation


1. Mutations are generally recessive, but dominant mutations do occur.
2. Mutations are generally harmful to the organism, 0.1 percent are beneficial.
3. Mutations are random that they may occur in any gene.
4. Mutation are recurrent, the same mutation may occur again and again.
5. Induced mutation commonly shows pleotropic, due to linked genes.