Genetically Modified Plants

This chapter focuses on genetically modified (GM) plants. A GM plant is defined as a plant that is produced using transgenic methods. These plants are also called transgenic or genetically engineered plants. Transgenic methods are molecular methods that enable the transfer of a gene or potentially a group of genes from an individual of one species to an individual or individuals of a different species. Currently, there are two common methods by which purified genes are introduced into plant cells: one uses the Ti plasmid of Agrobacterium tumefaciens to transfer the gene as a part of the plasmid; the other uses a metal particle or fiber or an electric pulse to pierce the cell wall and carry the gene into the nucleus (also called gene gun or electroporation). All of the insecticidal-transgenic crops currently available are based on cry toxin genes from B. thuringiensis, and a few now under development are based on other toxin-coding genes from B. thuringiensis. The cry genes code for crystalline proteins that are toxic to some insects. Most of transgenic crops under development aim to address one of four broad needs: improved agricultural characteristics, improved post-harvest processing, improved food quality and other novel products for human use, and improved mitigation of environmental pollution. Furthermore, the limitations and potential adverse effects of transgenic or genetically engineered plants are discussed.