ABSTRACT
Protection by immunization against several fungal and bacterial diseases has been demonstrated under field conditions. Demonstrated that immunization of tobacco plants by stem injection of sporangial suspension of Peronospora tobacina protected the plants against blue mold as well as or better than most effective downy mildew fungicide, metalaxyl. Instead of using plant pathogens directly for immunization, possibility of using chemical elicitors, where known, produced by these pathogens to induce the host defense should be explored. Several terms such as seedling resistance, post-seedling resistance, and adult plant resistance have invariably been used to describe the exact stage of the host growth when it shows resistance. True resistance denotes incompatibility between the host and the parasite. It implies that so long as the incompatibility exists the host should ward off infection by the pathogen. Coat protein gene got integrated with host's genome and was expressed in transgenic plants.
