Abstract：
Chromium (Cr) is an highly toxic metal 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 are not yet completely known in plants. Herein, were identified the epigenetic changes induced by chronic and acute Cr stress treatments in Arabidopsis thaliana plants using Methylation Sensitive Amplification Polymorphism coupled with next-generation sequencing (MSAP-Seq). First-generation Arabidopsis plants (termed F0 plants) kept under hoagland solution were subjected to Cr stress treatments. For chronic Cr stress, plants were treated through hoagland solution with 2.5 μM Cr during the entire cultivation period until seed harvest. Meanwhile, for acute Cr stress, plants were treated with 5 μM Cr during the first three weeks and returned to unstressful control condition until seed harvest. Seeds from F0 plants were sown and F1 plants were re-submitted to the same Cr stress treatments. The seed germination rate was evaluated from F-2 seeds harvested of F1 plants kept 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 F-2 seeds originating from stressed F1 plants compared to F-2 seeds harvested from 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 using MSAP-Seq. 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 maintain plant defenses activated. In particular, RNA processing, protein translation, photorespiration, energy production, transmembrane transport, DNA transcription, plant development, and plant resilience were the major biological 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 over generations based on DNA methylation to modulate defense and resilience mechanisms.
摘要：
铬（Cr）金属对植物有剧毒，对植物的生长造成严重破坏，发展,和繁殖。植物暴露于慢性和急性铬胁迫处理导致显著的变化在短时间内的基因表达谱和在长时间的基因组DNA甲基化谱在一个跨代水平，因此,在基因表达中。植物中Cr胁迫施加的这些表观遗传修饰及其含义尚不完全清楚。在这里，使用甲基化敏感扩增多态性方法结合下一代测序（MSAP-Seq）鉴定了拟南芥植物中Cr胁迫处理诱导的表观遗传变化。将保持在hoagland溶液中的拟南芥植物保持在慢性和急性Cr胁迫处理下（称为F0植物）。对于慢性压力，在整个培养期间，用2.5μMCr通过hoagland溶液处理植物，直到种子收获。同时,对于急性压力，在前三周用5μMCr处理植物，并恢复到无压力条件，直到种子收获。播种来自F0植物的种子并重新进行相同的Cr胁迫处理。与无压力对照条件相比，在不同Cr胁迫处理（0、10、20和40μM）下评估了F2植物的种子发芽率。这些数据显示，与无压力的对照植物相比，来自压力F1植物的种子发芽率发生了显着变化。鉴于这些数据,通过MSAP-Seq方法评估了在这些慢性和急性Cr胁迫处理和无压力控制条件下保存的F1植物的跨代表观遗传修饰。MSAP-Seq数据显示，由于慢性和急性Cr胁迫处理以激活植物防御，一些基因的甲基化状态被修饰。特别是,RNA加工，蛋白质翻译，光呼吸,能源生产，跨膜运输，DNA转录，植物发育,和植物恢复力是在慢性和急性Cr胁迫下保持的F1植物中鉴定出的表观遗传机制调节的主要过程。因此,集体数据表明，在Cr胁迫下保持的拟南芥植物基于DNA甲基化调节其表观遗传状态，以调节防御和弹性机制。
