University of Nebraska Center for Biotechnology and Center for Plant Science Innovation, 1901 Vine Street, Lincoln, NE, 68588, USA.
Plant J. 2014 Jul;79(1):150-61. doi: 10.1111/tpj.12548. Epub 2014 Jun 17.
Plants subjected to a prior dehydration stress were seen to have altered transcriptional responses during a subsequent dehydration stress for up to 5 days after the initial stress. The abscisic acid (ABA) inducible RD29B gene of Arabidopsis thaliana was strongly induced after the first stress and displayed transcriptional memory with transcript levels nine-fold higher during the second dehydration stress. These increased transcript levels were due to an increased rate of transcription and are associated with an altered chromatin template during the recovery interval between the dehydration stresses. Here we use a combination of promoter deletion/substitutions, mutants in the trans-acting transcription factors and their upstream protein kinases, and treatments with exogenous ABA or dehydration stress to advance our understanding of the features required for transcriptional memory of RD29B. ABA Response Elements (ABREs) are sufficient to confer transcriptional memory on a minimal promoter, although there is a context effect from flanking sequences. Different mutations in Snf1 Related Protein Kinase 2 (SnRK2) genes positively and negatively affected the response, suggesting that this effect is important for transcriptional memory. Although exogenous ABA treatments could prime transcriptional memory, a second ABA treatment was not sufficient to activate transcriptional memory. Therefore, we concluded that transcriptional memory requires ABA and an ABA-independent factor that is induced or activated by a subsequent dehydration stress and directly or indirectly results in a more active RD29B chromatin template. These results advance our knowledge of the cis- and trans-acting factors that are required for transcriptional memory of RD29B.
在初次胁迫后经历过先前脱水胁迫的植物，在随后的脱水胁迫中，其转录反应会发生改变，这种改变可持续长达 5 天。拟南芥的 ABA 诱导 RD29B 基因在初次胁迫后强烈诱导，表现出转录记忆，在第二次脱水胁迫时转录水平高出 9 倍。这些转录水平的增加是由于转录率的增加，并且与脱水胁迫之间的恢复间隔期间的染色质模板改变有关。在这里，我们使用启动子缺失/取代、转录因子及其上游蛋白激酶的突变体以及外源 ABA 或脱水胁迫处理的组合，来深入了解 RD29B 转录记忆所需的特征。ABA 反应元件 (ABREs) 足以赋予最小启动子转录记忆，尽管侧翼序列存在上下文效应。Snf1 相关蛋白激酶 2 (SnRK2) 基因的不同突变对该反应具有正向和负向影响，表明该效应对转录记忆很重要。虽然外源 ABA 处理可以启动转录记忆，但第二次 ABA 处理不足以激活转录记忆。因此，我们得出结论，转录记忆需要 ABA 和一种 ABA 非依赖性因子，该因子由随后的脱水胁迫诱导或激活，并直接或间接导致更活跃的 RD29B 染色质模板。这些结果提高了我们对 RD29B 转录记忆所需的顺式和反式作用因子的认识。
