MAJOR UNANSWERED QUESTIONS AND FUTURE DIRECTIONS
Today's “Holy Grail” is to define the molecular basis of disease resistance specificity. We also need to elucidate the biochemical functions of pathogen avirulence proteins and plant R proteins. Moreover, we must focus on better understanding what controls the defense signal transduction pathways in the host leading to the expression of resistance. During the course of this work we expect to uncover the answer to the question: Do resistance proteins bind directly or indirectly to pathogen avirulence proteins or are there protein complexes that form that contain several yet to be identified proteins in addition to R and Avr proteins? The answer to this question is expected to come in the next few years as we begin to define the precise mechanisms involved in plant disease resistance. The major advances in this field up until this time have been shaped by genetic approaches, but it is also quite clear that a concomitant biochemical and cell biological effort will also be necessary to unravel the molecular complexities to understand the mechanisms involved in plant disease resistance.
A major future goal is to be able to understand the molecular basis of disease resistance in enough detail to make precise predictions about engineering plants to express resistance proteins that can recognize pathogen molecules essential for pathogenicity. In this manner it is anticipated that biotechnological approaches can engineer durable disease resistance in agricultural crops.