Diel and seasonal oscillations are two major environmental changes in nature. While organisms cope with the former by the well-characterized mechanism of the circadian clock^1,2, there is limited information on the molecular mechanisms underlying long-term responses to the latter^3,4,5. Histone H3 lysine 27 trimethylation (H3K27me3), a repressive histone modification, imparts stability and plasticity to gene regulation during developmental transitions^6,7,8,9. Here we studied the seasonal and diel dynamics of H3K27me3 at the genome-wide level in a natural population of perennial Arabidopsis halleri and compared these dynamics with those of histone H3 lysine 4 trimethylation (H3K4me3), an active histone modification. Chromatin immunoprecipitation sequencing revealed that H3K27me3 exhibits seasonal plasticity and diel stability. Furthermore, we found that the seasonal H3K27me3 oscillation is delayed in phase relative to the H3K4me3 oscillation, particularly for genes associated with environmental memory. Our findings suggest that H3K27me3 monitors past transcriptional activity to create long-term gene expression trends during organismal responses over weeks in natural fluctuating environments.

狄尔和季节性振荡是自然界的两个主要环境变化。虽然生物通过昼夜节律时钟^1,2的良好表征的机制来应对前者，但有关对后者^3,4,5长期响应的分子机制的信息有限。组蛋白H3赖氨酸27三甲基化（H3K27me3），一种抑制性的组蛋白修饰，在发育过渡^6,7,8,9中为基因调控赋予稳定性和可塑性。在这里，我们研究了多年生拟南芥自然种群中全基因组水平上H3K27me3的季节性和diel动态。并将这些动态与组蛋白H3赖氨酸4三甲基化（H3K4me3）（一种有效的组蛋白修饰）进行了比较。染色质免疫沉淀测序表明，H3K27me3具有季节性可塑性和diel稳定性。此外，我们发现季节性H3K27me3振荡相对于H3K4me3振荡在相位上有所延迟，特别是对于与环境记忆相关的基因。我们的发现表明，H3K27me3可以监视过去的转录活性，以在自然波动的环境中持续数周的生物反应期间创建长期的基因表达趋势。