Experience of transient environmental stress can prepare (“prime”) the phenotype of an organism for improved responses to impending stress. Successful priming of a stress response by a past environmental cue requires memory of the past experience. While ample knowledge is available on memory processes in animals, we need a deeper understanding of how organisms lacking a nervous system store an environmental experience, how they retrieve the memory and how it affects the response to impending stress. In addition to these mechanistic “how”-questions, scarce knowledge is available on the ecological traits that determine the benefit of remembering a past stress. The Collaborative Research Centre (CRC) 973 focuses on studies of (1) the mechanisms of priming and memory of stress responses in organisms without nervous systems and (2) the ecological conditions favouring priming and memory. The CRC 973 projects investigate priming and memory of stress responses especially in plants, but also in bacteria and fungi. Hence, organisms with different life strategies are studied, i.e. r-selected species with a high reproduction rate and short life time, and K-selected ones with a lower reproduction rate and longer life time. The stressors applied include abiotic (cold, heat, light) and biotic (antimicrobial peptides, phytopathogens, herbivorous insects) stimuli, thus allowing for comparative analysis of priming processes with regard to the type of stressor.

In phase II, CRC 973 intends to further pursue its strategic aim, namely to more tightly link research in molecular biology and biochemistry with ecology. Reaching this aim will be supported by a CRC-implemented programme for PhD students; this Integrated Research Training Group (IRTG) programme offers teaching in the various biological disciplines covered by CRC 973, ranging from molecular biology and biochemistry to ecology.

CRC 973 will place special research emphasis on the temporal and spatial aspects of the priming process. We intend to investigate (i) which factors determine the temporal course of priming and the persistence of memory and which ones regulate “forgetting” of information, i.e. resetting the primed state to the non-primed one, and (ii) how priming information is spatially transmitted within a plant from seeds, meristems or fully developed tissue to later developing tissue. The latter question will be addressed by analysing epigenetic information transfer via mitosis and the functional relevance of transcription factors and phytohormones. Furthermore, we will study – in addition to the role of the organism´s life strategy – some further ecological factors that may shape priming and memory processes, i.e. the impact of the age of the primed target organism and the role of the presence of competitors and predatory species. Field studies will investigate the ecological relevance of priming under natural conditions. In addition, a project working with bacteria will investigate the evolution of phenotypic primability for improved stress resistance.