Stress memory in crops: what we have learned so far

Abiotic stresses are among the primary environmental variables that have consistently posed challenges to agricultural production worldwide. In the last decades, our understanding of how plants sense environmental cues has greatly expanded. This encompasses the mechanisms that convert environmental stress signals into cellular signaling pathways and gene transcription networks. Moreover, emerging evidence indicates that plants have the capacity to retain memories of past stressful experiences and use such capacity to enhance their responses under recurrent stresses. Priming, through prior exposure to a triggering factor, improves plant tolerance to subsequent biotic or abiotic stresses and has been proposed as the basis for plant stress memory. Priming-induced stress memory can persist in the current generation or even in the progeny. The significance of stress memory in enhancing abiotic stress tolerance is well-established in several important crops, and the capacity of plants to retain stress-related memories has been linked to diverse plant mechanisms. In this review, we revisit the recent literature reporting the mechanistic underpinnings of abiotic stress memory in important crops. We outline the underlying processes related to acquisition of stress memory, occurring at molecular, physiological, biochemical, and morphological levels. Here, we addressed the methods for studying plant memory over the last ten years, giving special attention to growth conditions, phenological stages and the techniques for inducing crop memory. Enhancing our comprehension of stress memory-related mechanisms would open up a range of possibilities for developing stress-resistant genotypes through molecular breeding or biotechnological methods or even stress-resistant crop fields due to improved management practices.