ABSTRACT
Plant diseases caused by fungal, viral, and bacterial pathogens are responsible for most heavy crop losses encountered in agriculture. Large stands of monoculture crops are especially susceptible to diseases that are difficult to control by conventional breeding or other means. Resistance genes currently present in the germplasm may be inadequate for certain diseases. In addition, new races of pathogens that overcome resistance genes may arise in a short period. Historically, heavy applications of chemical fungicides have often been required to minimize the crop losses. However, since chemical fungicides have potentially deleterious environmental and health consequences, it is desirable to enhance the plant’s ability to combat diseases. Genetic engineering methods provide an attractive alternative to other more conventional approaches.
