Mutagenic agents

The chemical substances and environmental conditions which cause mutations in the organisms are called mutagens or mutagenic agents. There are two kinds of mutagenic agents – physical and chemical mutagenic agents.

Physical mutagenic agents

Electromagnetic radiation, radiations like ultraviolet rays, temperature, etc. are some of the examples for physical mutagens. X-rays and gamma rays are ionizing radiations which induce mutation in seeds. UV rays are nonionizing radiations. Pollen can be treated with UV since pollen has germinal nucleus in which mutation can be caused.

Chemical mutagenic agents

Chemicals can also be used for inducing mutations in the organisms. Such chemicals are called chemical mutagenic agents. eg. Nitrous acid, Methyl methane sulphonate (MMS) and ethyl methane sulphonate (EMS). Ethyl methane sulphonate
has been extensively used for inducing mutations in microorganisms, higher plants and animals.

Significance of mutation

Mutations play an important role in the origin of new species and serves as a tool for evolution.
Induced mutations are useful in agriculture, animal husbandry and biotechnology to produce new strains. For example, mutant strains of Penicillium produces more penicillin.
It is one of the best approaches for improvement of crops.
Induced mutants are reported in paddy, wheat, soyabeans, tomatoes, oats, and barley. Mutant varieties of wheat are early maturing, disease resistance and they are enriched with protein. Mutant varieties of paddy produce many tillers with long grains.
The study of mutant strains of viruses helps us to know the fine structure of gene. The genes are made up of small functional units such as cistron, recon and muton. Cistron is an unit of function, recon is the unit of recombination and muton is the unit of mutation.
Many types of mutations cause heritable diseases and cancer in human beings.