Plant defense priming in the field: a review

Plant defense priming is a form of plant immunological “memory” in which an external stimulus is perceived by the plant as a warning signal that leads to a minor activation of induced defense mechanisms. This challenge is memorized and leads to a faster and/or stronger defense response upon subsequent attack by a pest or pathogen. The external stimulus in question can be chemical, biotic (a pest, pathogen, or beneficial microbe), or abiotic (an environmental stressor). This review focuses on chemical priming agents, that is, small compounds and macromolecules with priming activity.Although priming has been extensively studied in the lab, comparatively few priming agents have made the transition to commercial use in agriculture and horticulture. The principal objective of this review is to summarize the available literature on the efficacy of priming agents in field conditions. In addition, the effect of priming on interactions with beneficial organisms and the integration of priming agents into broader integrated pest management programs will be discussed.