Genetic engineering will enable the plant or animal breeder to select the particular gene from one plant and then place the same gene into another plant for it to express its desired character.
Today, genetic engineering is widely employed as a tool in modern crop improvements.
Recombinant DNA technology, popularly termed ‘gene cloning’ or ‘genetic engineering’ offer unlimited opportunities for creating new combination of genes that at the moment do not exist under natural conditions.
Genetic engineering can be defined as the formation of new combinations of heritable material by the insertion of foreign nucleic acid molecule from other sources.
The foreign genes are generally incorporated into a host organism
either through a bacterial plasmid or a virus, which acts as vectors (vehicular traffic). Genes are compared to biological software and are the programs that drive the growth development and functioning of an organism.
By changing the software in a precise and controlled manner, it becomes possible to produce desired changes in the characteristics of the organisms.
eg. E. coli is made to produce human insulin by introduction of human insulin producing gene into bacterial plasmid.
Genetic engineering is a tool used in modern crop improvement
programs. Its objective is to isolate and introduce a gene or genes into a crop plant that normally does not possess them.
Addition of genes or DNA (foreign genes) from one plant or a microbe to another plant is called transgenic plant.
Herbicide resistance, saline resistance, altered flower colour, improved protein quality and protection against viral infection are few examples of recently formed transgenic higher plants by using this technology eg. tobacco, tomato, potato, sunflower and apple.
Improvement of a crop lies in its genetic make up and the environment in which it grows and interacts. An improved variety is one that is superior to other existing varieties in one or few characters. It may show high yield than other varieties, early maturity, disease and pest resistance.
A new improved variety is developed by continuous breeding experiments as described above under various methods. By making use of modern technologies, like biotechnology, tissue culture and conventional breeding methods new improved crops are obtained with desirable characters that suits well to the existing environment without polluting or altering it in any way.
In order to release a newly created variety it takes nearly 12 years involving extensive field trials, naming and multiplication.
Role of biofertilizers
Extensive use of fertilizers and chemical pesticides had resulted in
soil and water pollution. Fossil fuels such as petrol and coal are used in the manufacture of fertilizers and pesticides.
To reduce pollution and over usage of our non-renewable resources like coal, petroleum, etc., an alternative method has been successfully developed to safeguard natural resources.
To maintain soil fertility and soil improvement, fertilizers of biological origin called biofertilizers have been developed. Artificial inoculation of rice and other crop fields with cyanobacteria (Anabaena, Calothrix, Gleocapsa, Lyngbya, Nostoc, Oscillatoria, Scytonema) has attracted much attention to increase fertility in several countries.
The term ‘biofertilizer’ denotes all the nutrient inputs of biological origin for plant growth. Biological origin refers to microbes producing nitrogen compounds. Bacteria and cyanobacteria are known to fix atmospheric nitrogen and are known as biofertilizers.
Nitrogen fixing bacteria like Azotobacter, Bacillus and Rhizobium increased the crop yield to 20%. Pseudomonas striata are used as seed inoculants as biofertilizer coats for cereals.