ABSTRACT
Genetic improvement of crop plants is not new; we have been modifying plant genomes for thousands of years for our well-being. Development of transgenic crop plants is an outcome of increasing human population and incidence of biotic/abiotic stress determinants. The cost-effective approach of genetic engineering allows for a relatively fast cross-species gene transfer. A number of crop plants have been genetically engineered for resistance to insect pests, fungal and viral pathogens, nematodes etc. using a variety of approaches. Genetically modified crop plants have been developed for tolerance to various abiotic stress conditions such as osmosis, salt, drought, temperature, environmental pollutants and so on. Plants have been engineered for better nutrient utilization as well as enhancement of nutrition quality in food. Crop plants have been engineered for molecular farming in order to generate sufficient antigenic vaccines, antibodies, netraceutical and therapeutic proteins. Recently, plant genomes have also been modified for enhancement in the production of biofuel. It is natural to think about the biosafety aspects of transgenic crop plants especially with respect to health and ecological issues. The cause of concern arises due to the phenomena of various types of gene flow in nature. The selectable markers can be removed from the genetically engineered plants using approaches such as co-transformation, multi-autotransformation, site-specific recombination, Cre/lox recombination system etc. Recently, genome editing technology, which allows plant breeding without introducing a transgene, is expected to generate many new crop varieties with traits that can satisfy various kinds of demands for commercialization genetically improved crop plants.
