Fig. 4.

Model summarizing a putative epigenetic mechanism preventing the transmission of “stress memory” to progeny. Schematic illustration on a possible chromatin states upon heat stress. Although heterochromatic loci are transcriptionally activated by temperature stress in WT and mom1 mutants, they are rapidly resilenced after stress is removed. Stress-induced transcription is hyper-activated and persists longer in ddm1 mutants than in WT and mom1; however, the altered transcriptional status is not transmitted to the progeny. In contrast, stress-induced transcriptional activation in ddm1 mom1 double mutants is transgenerationally inherited. The transcriptional activation in ddm1 mom1 could persist due to altered positioning of nucleosome or other modifications of chromatin properties.