Perspective on genetic engineering of agricultural crops for resistance to disease

Plant breeding has been the classical means of manipulating the plant genome to develop resistant cultivars for controlling plant diseases. However, genetic engineering provides an entirely new approach. Although, currently, the area planted with crops genetically modified for resistance to disease is small compared with that of crops genetically modified for tolerance to herbicides or resistance to insects, numerous strategies are being pursued to render plants resistant to viruses, fungi, bacteria, and nematodes. Risks associated with the use of transgenic crop plants for agricultural food production may relate to the use of specific transgenes, marker genes, or gene control sequences, whereas other concerns address the entire approach of engineering heterologous genes into plants. Inherent risks can be mitigated by new and innovative strategies, and transgenic plants can be produced within a regulatory framework. If genetically modified plants are to be regulated, it is inevitable that methods will be required to distinguish between transgenic and nontransgenic plants and their products. Analytical laboratory tests may be directed toward novel gene products or the gene construct itself and must take both theoretical and practical detection limits into consideration. With a judicious approach, disease-protected transgenic plants may yet prove to be essential for producing a safe and adequate world food supply without endangering the environment or jeopardizing plant diversity.