Mutations and its role in plant breeding

Ahmed Shehab Abd-allah

    The term mutation refers to the changes that occur in the genetic material and the process by which this change occurs. The organism that shows a new phenotypic form as a result of a mutation is called a mutant. In other words, a mutation is a sudden, continuous change in the genetic structure of the organism, it is inherited through generations. This definition does not include the new unions resulting from crossing over.

   Mutation is a major source of genetic variations in nature which provides the possibility of evolution for the purposes of adapting to new environmental changes.

On the other hand, increasing the rate of mutation probably resulted in an irregular transmission of genetic information accurately from one generation to another. Mutations can be occurred at the level of chromosomes, then called chromosomal mutations or it can be at the level of genes (at the molecular level) and called genetic mutations. The mutations can be natural or artificial (innovative), the development of short varieties of Sorghum Bicolor is example of the use of natural mutations in plant breeding. Where the old varieties are long and harvested manually, while there are many means that help to create the industrial mutations. Radioactive materials and chemicals are the two important means that can be used to obtain artificial mutations in plants, thus providing plant breeders with genetic differences that can be selected for the purpose of improvement.

   The proceedings taken in the use of different mutations vary according to the species differences, purposes, and parts of the treated plant. Mostly, the use of radiation treatments is usually on the seeds for several reasons, namely the seeds can be treated under more controlled conditions of humidity, temperature, oxygen level and atmospheric pressure, in addition to that large number of seeds can be processed at the same time.

In Iraq, a plan has been drawn up since 1969, aiming primarily at the possibility of benefiting from nuclear energy in the agricultural sector to contribute to the advancement of agricultural production to a level commensurate with the requirements of qualitative transformation. Among the research that is at the forefront is related to radioactive stimulation for the growth, development and production of agricultural crops such as wheat, barley, maize and sunflower under country conditions by treating seeds in relatively low doses with gamma rays since such research gives relatively quick results compared to other research, there are some drawbacks when using this method can be summarized as follows:

1- Most of the mutations that occur in the organism are harmful and a large percentage of them are lethal.

2- The average of beneficial mutations is low, and very large numbers of plants must be cultivated and examined in order to find among its the appropriate mutation.

3- Mutant plants should be selected very carefully.

4- It is not possible to distinguish mutations with a small effect, which may become useful to plant breeders in the long run, and it is known that they do not cause an imbalance in the genetic structure of the plant, such as large mutations.

Benefits of the mutation breeding method:

1- The most important benefits of this method is the production of non-existent differences, so the use of mutations in breeding makes the plant breeder not completely dependent on nature in the preparation of the raw material, and this means that the differences are not the result of recombination as in cross-breeding, but in this case they are authentic and a new creation.

2- When there is no possibility of improvement by the methods used in plant breeding, taking into account the availability of differences, the only alternative as mentioned previously is breeding by using mutations.

3- In some special cases, the use of mutations in breeding may play an important role in breeding and improving crops.

Therefore, it requires the use of mutations for the purposes of breeding by radiation for the purpose of developing varieties of improved crops and important commercial strains that are suitable for the environment, where it is considered one of the best ways to use atomic energy for peaceful purposes.