The Arabidopsis DNA methylome is relatively impervious to abiotic stress

Improving plant stress response holds great agricultural potential. One promising, yet speculative, possibility is the formation of plant stress memory facilitating enhanced responses to recurring stress. One possibility is the involvement of environmentally-induced variation in reversible chromatin marks, such as DNA methylation, leading to the altered regulation of underlying genetic elements that promote enhanced stress tolerance. Such potential has spurred numerous investigations yielding conflicting results, thus it remains unclear whether robust stress-induced chromatin variation can encode plant stress memory conveying enhanced stress tolerance. Herein we investigate for the possibility of stress-induced alterations in DNA methylation to convey stress memory, both on mitotic and transgenerational timescales, such that previously stressed plants show improved stress tolerance with correlated alterations in DNA methylation at stress-responsive loci. We find that although the experience of stress may be stored mitotically, it does not appear to be transmitted meiotically and is independent of DNA methylation changes. Overall, the DNA methylome appears to be robust against stress-induced variation and is unlikely to contribute to any form of stress memory. Overall design: Whole genome bisulfite sequencing was performed on plants exposed to a nine day drought stress ('mitotic drought', 3 biological replicates), repeated excess light stress over 1 week (1xWLRS, 3 biological replicates) and on progeny of 5th generation plants ('G5', 6 biological replicates per treatment) from independent lineages that were propagated by single seed descent under control conditions ('Watered') or with a recurring drought stress ('Drought') every generation.