During their lifespan, plants respond to a multitude of stressful factors. Dynamic changes in chromatin and concomitant transcriptional variations control stress response and adaptation, with epigenetic memory mechanisms integrating environmental conditions and appropriate developmental programs over the time. Here we analyzed transcriptome and genome-wide histone modifications of maize plants subjected to a mild and prolonged drought stress just before the flowering transition. Stress was followed by a complete recovery period to evaluate drought memory mechanisms. Three categories of stress-memory genes were identified: i) "transcriptional memory" genes, with stable transcriptional changes persisting after the recovery; ii) "epigenetic memory candidate" genes in which stress-induced chromatin changes persist longer than the stimulus, in absence of transcriptional changes; iii) "delayed memory" genes, not immediately affected by the stress, but perceiving and storing stress signal for a delayed response. This last memory mechanism is described for the first time in drought response. In addition, applied drought stress altered floral patterning, possibly by affecting expression and chromatin of flowering regulatory genes. Altogether, we provided a genome-wide map of the coordination between genes and chromatin marks utilized by plants to adapt to a stressful environment, describing how this serves as a backbone for setting stress memory.

中文翻译：

---

玉米适应干旱和恢复后的胁迫适应和开花调节的表观遗传特征。

在生命周期中，植物对多种压力因素做出反应。染色质的动态变化和伴随的转录变异控制应激反应和适应，表观遗传记忆机制将环境条件和适当的发育程序整合在一起。在这里，我们分析了在开花过渡期之前遭受轻度和长期干旱胁迫的玉米植物的转录组和全基因组组蛋白修饰。紧随其后的是一个完整的恢复期，以评估干旱记忆机制。鉴定了三类应激记忆基因：i）“转录记忆”基因，其在恢复后持续稳定的转录变化；ii）“表观记忆候选者” 在没有转录变化的情况下，应激诱导的染色质变化的基因比刺激持续的时间更长；iii）“延迟记忆”基因，不会立即受到压力的影响，但会感知并存储压力信号以延迟响应。在干旱反应中首次描述了这种最后的记忆机制。另外，施加的干旱胁迫可能通过影响开花调控基因的表达和染色质来改变花型。总而言之，我们提供了基因组和染色质标记之间的协调性的全基因组图，植物利用这些染色体来适应胁迫环境，描述了它如何作为设置胁迫记忆的骨架。但可以感知并存储压力信号，从而延迟响应。在干旱反应中首次描述了这种最后的记忆机制。另外，施加的干旱胁迫可能通过影响开花调控基因的表达和染色质来改变花型。总而言之，我们提供了基因组和染色质标记之间的协调性的全基因组图，植物利用这些染色体来适应胁迫环境，描述了它如何作为设置胁迫记忆的骨架。但可以感知并存储压力信号，从而延迟响应。在干旱反应中首次描述了这种最后的记忆机制。另外，施加的干旱胁迫可能通过影响开花调控基因的表达和染色质来改变花型。总而言之，我们提供了基因组和染色质标记之间的协调性的全基因组图，植物利用这些染色体来适应胁迫环境，描述了它如何作为设置胁迫记忆的骨架。