Figure 1.

Abiotic and biotic stress conditions (a) can change gene expression with and without involving plant stress hormones (b). Transcription changes, or stress factors directly, can affect chromatin via DNA methylation, histone tail modifications, histone variant replacements, or nucleosome loss and chromatin de-condensation (c, d). These changes are largely reversible but can modify metabolic or morphologic plant features under stress conditions. Usually, the new phenotypes are not transmitted to progeny. However, chromatin-associated changes have the potential to be heritable and might result in uniform maintenance of new features or new combination and epigenetic diversity (e).