ABSTRACT
Transfer of genes between plant species has played an important role in crop improvement for many decades. Genetic transformation facilitates introduction of only specifically desirable genes without co-transfer of any undesirable genes from donor species which normally occurs by conventional breeding methods. The first generation application of genetic engineering to crop agriculture has been targeted towards the generation of transgenic plants expressing foreign genes that confer resistance to viruses, insects, herbicides or post harvest deterioration and accumulation of useful modified storage products. The chapter discusses various resistance to biotic stresses: insect resistance, viral resistance, and fungal and bacterial disease resistance. Attempts to isolate disease resistance and avirulence genes have gained momentum primarily because of the development of map based cloning and gene tagging strategies. The strategy of genetic engineering hypersensitive cell death in response to fungal pathogen attack at the site of infection has been employed successfully.
