It has long been recognized that a plant's ability to resist infection by a particular pathogen is an inherited characteristic. Furthermore, it is also the first example of an insect-resistance gene in a family of plant genes whose members confer resistance to other plant pests by recognizing the protein product of a corresponding gene in the pest. Superficially, these pests bear little resemblance to each other, but a closer examination show there are similarities in feeding between aphids and nematode worms.
Aphids suck sap from leaf veins and worms suck plant fluids from roots.
The picture that is emerging is that as plant and pathogen come face to face, the plant defence response is initiated by the plant's recognition of specific signal molecules produced by the pathogen, which set off a cascade of signalling events that culminate to form the plant defence response. The researchers suggest that the ability of the pathogen to defeat crop plant resistance is due to avoiding the recognition event between plant and pathogen rather than a breakdown in the late signalling events. The researchers go on to demonstrate that inserting Mi genes into tomato plants that are vulnerable to aphid attack, makes these plants resistant to certain populations of aphids but not to others. Thus diseases caused by the more specialized pathogens, such as cereal rusts, late blight of potato and many other potentially devastating diseases, resistance triggered by early recognition would lead to an efficient and nearly protective response with obvious benefits to growers and consumers alike.