Mutation breeding

"A sudden heritable change in a traits of an organism is called mutation". The agents inducing the mutation are called mutagens and process is known as mutagenesis. Mutation breeding is the method of improving the crops through inducing mutagenesis.

Mutagens utilized in mutation breeding

A number of physical and chemical mutagens for plants are identified. Among them, γ-rays and X-rays are most commonly utilized physical mutagens. Ethyl methane sulphonate(EMS), ethylene imine (EI) and sodium azide are most common chemical mutagens utilized in plant breeding programs. Plants are treated with γ-rays in Gamma gardens.

Achievements

A number of plant varieties have been developed through mutation breeding at various breeding stations of the globe. Sharbati Sonora of wheat, Jagannath of rice, Co 8152 of sugarcane, etc. are some the crops developed in India through the mutation breeding.

Sharbati sonora

Sharbati sonora is produced by M.S. Swaminathan (Father of Green revolution in India) and his team from the Sonora 64 (a Mexican semi-dwarf variety introduced from Mexico) by γ irradiation.

Gamma garden

Gamma garden is also known as atomic garden, where γ-rays from the Cobalt-60 or Cesium-137 are used for creating the mutation in the plants under controlled condition. Gamma garden are developed for peaceful use of atomic energy, where it is used in plant breeding programs.

Merits

• Creation of new traits:
  Mutation creates new traits in plants.
• Breaking undesirable linkage:
  Mutation breaks the undesirable linked traits.
• Production of haploids:
  Haploid plants are produced by treating the pollen grains or unfertilized eggs with X-rays.

Demerits

• Unpredictability:
  The frequency of desired mutant trait is very low (about 0.1 %). Hence, large population size is required.
• Difficulty in detection:
  Desired qualitative characters (e.g., disease resistance) in mutants are difficult to detect, as it need elaborate test. Further, most of the mutations are recessive, hence are hard to identify in polyploid species.
• Undesirable traits:
  Mutation sometimes result in the expression of undesirable characters, which are remove by back-cross method. This consumes more time and labor.

---

First published on 13-04-2021
Last updated on 06-05-2021