Epigenetic and chromatin-based mechanisms in environmental stress adaptation and stress memory in plants

Abstract

Plants frequently have to weather both biotic and abiotic stressors, and have evolved sophisticated adaptation and defense mechanisms. In recent years, chromatin modifications, nucleosome positioning, and DNA methylation have been recognized as important components in these adaptations. Given their potential epigenetic nature, such modifications may provide a mechanistic basis for a stress memory, enabling plants to respond more efficiently to recurring stress or even to prepare their offspring for potential future assaults. In this review, we discuss both the involvement of chromatin in stress responses and the current evidence on somatic, intergenerational, and transgenerational stress memory.

Fig. 1

Priming modifies responses to a triggering stress cue. A naϊve plant may be primed by exposure either to stress or to other priming cues such as volatiles. Upon exposure to a triggering stress cue, the response pattern differs markedly in primed and naïve plants. The primed plant may respond to the triggering stress cue faster/earlier or more strongly than a naïve plant. It may also respond in a sensitized fashion so that the response is triggered at a lower threshold. The primed plant may further change its response pattern to regulate a network of genes that differs from that involved in a naïve plant. None of these responses are exclusive and combinations thereof probably occur

Fig. 2

Molecular features of somatic stress memory in response to abiotic stress cues. Somatic priming of plants by an abiotic (hyperosmotic, drought, or heat) stress cue has common features that are displayed in the central box. Other properties have as yet only been implicated in a specific stress. Notably, this apparent specificity is based on current knowledge rather than on explicit exclusion (right boxes, color-coding as indicated on the left). HSF heat shock factor