Sudden, stable discontinuous and inheritable variations which appear in organism due to permanent change in their genotype.
Mutations which occur naturally, i.e., both germinal and somatic.
Mutations produced in response to a treatment with a mutagen. They were first produced by Muller (1927) with the help of X-rays on Drosophila and by Stadler in maize.
Rate of mutations is increased by means of certain factors and chemicals called mutagens. 2 types:
(i) Chemical mutagens:
A variety of chemicals like ethylmethane sulphonate (EMS) and sodium azide which induce mutations.
(ii) Physical mutagens:
Various kinds of radiations e.g., X-rays, gamma rays, ultraviolet rays etc.
Mutation can arise due to a change in any of the following:
(i) Chromosome structure
(ii) Chromosome number
(iii) Base sequence of the concerned gene.
The use of induced mutations in plant breeding to develop improved varieties. In such breeding usually seeds are treated with a suitable mutagen. The treated seeds are grown in the field and self-pollinated. Progeny from these plants are grown during the next crop season.
These plants are carefully observed to identify and select mutations of interest. In the end, a desirable mutant line may be obtained which may be good enough to be released as a new variety. Over 200 varieties have been produced from mutation breeding in India.