Ultrastructural Studies in Plant Disease Resistance

Abstract

Over the past two decades, a number of different approaches have been considered by plant pathologists toward enhancing plant disease resistance. Among these, the use of non-specific resistance elicitors as part of an integrated disease control strategy offers exciting opportunities. However, it is clear that unequivocal answers to key questions, including the stability and persistence of the induced host response, the efficiency of such agents, products and/or molecules under commercial conditions, and their suitability in an integrated crop protection system, need to be answered before elicitors can be considered as powerful crop protectants. In spite of these limitations, the recent advances in our fundamental understanding of the nature of microbially- and chitosan-mediated induced resistance in plants highlights the great potential of induced resistance in plant protection. The demonstration that pathogen growth and development were restricted or even halted and that structural and biochemical barriers were elaborated in plant tissues underlying areas of pathogen penetration gives reason to believe that induced resistance may be active against a wide array of pathogens and even insects, thereby increasing the level of resistance. It is clear that exploiting plant induced resistance as an alternative strategy of disease and pest management clearly meets with the current needs toward sustainable agriculture at a lower environmental cost. However, coordinated research efforts are still needed to develop programmes dealing with molecular genetic analyses, formulation studies, and large-scale experiments.