LECTURE NOTE PLANT – PATHOGEN INTERACTION The mode of attack of plant by plant pathogens

Plants exist in a world filled with microorganism. They continue to grow in the same location throughout the growing season or for many years, as in the case of perennial plants. Their surfaces are constantly exposed to bacteria, fungi, nematodes, and possibly parasitic plants. They may be inoculated with viruses during feeding by insects or by other vectors. Plant pathogens have made many adaptations to enable them to invade plants, overcome plant defense mechanisms, and colonize plant tissues for growth, survival, and reproduction. Once established inside the plant, they have at least temporarily escaped the intense competition from saprophytic organisms on plant surfaces and in the soil. Therefore, for a pathogen to infect a plant, it must be able to make its way in to and through the plant, obtain nutrients from the plant, and neutralize the defense reactions of the plant.