BOTANY Higher Secondary Second Year - Textbooks Online

Genetic engineering
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.
Improved varieties
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
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