ABSTRACT
Cultivated crop species are susceptible to attack from many phytopathogens, which results in major yield losses and deterioration in fruit quality. Incorporation of resistance to diseases is one of the major challenges faced by the breeders during the development of improved crop cultivars for agricultural use. Since the beginning of domestication of plants for
human use, diseases have caused major yield losses and have impacted the well-being of humans worldwide. Nearly all agricultural crop cultivars currently being used have some form of genetic resistance incorporated involving single or multiple genes that are characterized as having recessive or dominant effects against a number of diseases. Without the incorporation of these resistance genes, crop productivity and yield would be substantially reduced. The incorporation of disease resistance genes into plants has been successfully achieved either by using conventional breeding methods, or using genes of microbial origin effective against phytopathogens (Crute and Pink 1996, Punja 2001).
