Epigenetic changes induced by chronic and acute chromium stress treatments in Arabidopsis thaliana identified by the MSAP-Seq

Chromium (Cr) metal is highly toxic to plants and causes severe damage to their growth, development, and reproduction. Plant exposure to chronic and acute Cr stress treatments results in significant changes at short time in the gene expression profile and at long time in the genomic DNA methylation profile at a transgenerational level and, consequently, in gene expression. These epigenetic modifications and their implications imposed by the Cr stress in plants are not yet completely known. Herein, were identified the epigenetic changes induced by Cr stress treatments in Arabidopsis thaliana plants using the Methylation Sensitive Amplification Polymorphism approach coupled with next-generation sequencing (MSAP-Seq). Arabidopsis plants kept in hoagland solution were kept under chronic and acute Cr stress treatments (termed F0 plants). For chronic stress, plants were treated through hoagland solution with 2.5 μM Cr during the entire cultivation period until seed harvest. Meanwhile, for acute stress, plants were treated with 5 μM Cr during the first three weeks and returned to unstressful conditions until seed harvest. Seeds from F0 plants were sown and re-submitted to the same Cr stress treatments. The seed germination rate was evaluated for F2 plants under different Cr stress treatments (0, 10, 20, and 40 μM) compared to the unstressful control condition. These data showed significant changes in the germination rate of seeds originating from stressed F1 plants compared with unstressful control plants. Given this data, F1 plants kept under these chronic and acute Cr stress treatments and unstressful control condition were evaluated for the transgenerational epigenetic modifications by the MSAP-Seq approach. The MSAP-Seq data showed that several genes were modified in their methylation status as a consequence of chronic and acute Cr stress treatment to activate the plant defense. In particular, RNA processing, protein translation, photorespiration, energy production, transmembrane transport, DNA transcription, plant development, and plant resilience were the major processes modulated by epigenetic mechanisms identified in F1 plants kept under chronic and acute Cr stress. Therefore, collective data suggested that Arabidopsis plants kept under Cr stress regulate their epigenetic status based on DNA methylation to modulate defense and resilience mechanisms.