Molecular aspects of defence priming

Plants can be primed for more rapid and robust activation of defence to biotic or abiotic stress. Priming follows perception of molecular patterns of microbes or plants, recognition of pathogen-derived effectors or colonisation by beneficial microbes. However the process can also be induced by treatment with some natural or synthetic compounds and wounding. The primed mobilization of defence is often associated with development of immunity and stress tolerance. Although the phenomenon has been known for decades, the molecular basis of priming is poorly understood. Here, I summarize recent progress made in unravelling molecular aspects of defence priming that is the accumulation of dormant mitogen-activated protein kinases, chromatin modifications and alterations of primary metabolism.