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By employing rDNA technology to modify an organism's genes and produce desired features, genetic engineering involves changing an organism's genotype. The most widely used method of genetic engineering entails introducing foreign DNA via recombinant DNA vectors made through molecular cloning.

The development of genetically modified organisms has contributed to the development of desirable features like disease, pesticide, and herbicide resistance, as well as improved nutritional value and shelf life. Before the advent of contemporary biotechnology techniques, farmers had already devised methods for choosing plant types with desirable features.

Gene targeting is the use of rDNA vectors to change the expression of a particular gene, by introducing mutations into the gene, or eliminating the expression of a particular gene by removing part or all of the gene sequence from the organism's genome.