Knockdown of WHIRLY1 Affects Drought Stress-Induced Leaf Senescence and Histone Modifications of the Senescence-Associated Gene HvS40.
Knockdown of WHIRLY1 Affects Drought Stress-Induced Leaf Senescence and Histone Modifications of the Senescence-Associated Gene HvS40.
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DOI：
10.3390/plants5030037
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发表时间：
2016-09-06
期刊：
影响因子：
--
通讯作者：
Humbeck K
中科院分区：
文献类型：
--
作者：
Janack B;Sosoi P;Krupinska K;Humbeck K
质体核定位蛋白 WHIRLY1 被描述为叶片衰老的上游调节因子，与衰老相关基因（如 HvS40）的启动子结合。为了研究 WHIRLY1 对干旱胁迫诱导的早衰的影响，在正常和干旱胁迫条件下培养具有 RNAi 介导的 HvWHIRLY1 基因敲低的转基因大麦植物。通过生理参数和对衰老和干旱胁迫相关基因表达的研究来监测这些品系的叶片衰老过程。干旱处理加速了 WT 植物的叶片衰老，而 WHIRLY 1 敲除系 (RNAi-W1) 显示出保持绿色的表型。转基因植物中衰老相关基因和干旱胁迫响应基因的表达均被延迟。值得注意的是，WRKY 和 NAC 家族转录因子的表达在 WHIRLY1 积累受损的植物中受到影响，这两个家族已知在衰老和胁迫相关信号通路中发挥作用，这表明 WHIRLY1 是干旱胁迫诱导衰老的上游调节因子。为了揭示 WT 和 RNAi-W1 系中干旱诱导衰老开始时 HvS40 的表观遗传索引，通过染色质免疫沉淀分析了 HvS40 启动子和编码序列的组蛋白修饰的应激响应负载，并通过 qRT-PCR 进行定量。在野生型中，HvS40 基因的常染色标记 H3K9ac 在对照条件下较低，并且是响应干旱处理而建立的，表明表观遗传机制响应干旱胁迫的作用。然而，干旱胁迫并未导致 WHIRLY1 积累受损的植物中 H3K9ac 显着增加。结果表明，WHIRLY1 敲低会导致衰老延迟，涉及基因表达的各个方面，包括染色质结构的变化。
The plastid-nucleus located protein WHIRLY1 has been described as an upstream regulator of leaf senescence, binding to the promoter of senescence-associated genes like HvS40. To investigate the impact of WHIRLY1 on drought stress-induced, premature senescence, transgenic barley plants with an RNAi-mediated knockdown of the HvWHIRLY1 gene were grown under normal and drought stress conditions. The course of leaf senescence in these lines was monitored by physiological parameters and studies on the expression of senescence- and drought stress-related genes. Drought treatment accelerated leaf senescence in WT plants, whereas WHIRLY 1 knockdown lines (RNAi-W1) showed a stay-green phenotype. Expression of both senescence-associated and drought stress-responsive genes, was delayed in the transgenic plants. Notably, expression of transcription factors of the WRKY and NAC families, which are known to function in senescence- and stress-related signaling pathways, was affected in plants with impaired accumulation of WHIRLY1, indicating that WHIRLY1 acts as an upstream regulator of drought stress-induced senescence. To reveal the epigenetic indexing of HvS40 at the onset of drought-induced senescence in WT and RNAi-W1 lines, stress-responsive loading with histone modifications of promoter and coding sequences of HvS40 was analyzed by chromatin immunoprecipitation and quantified by qRT-PCR. In the wildtype, the euchromatic mark H3K9ac of the HvS40 gene was low under control conditions and was established in response to drought treatment, indicating the action of epigenetic mechanisms in response to drought stress. However, drought stress caused no significant increase in H3K9ac in plants impaired in accumulation of WHIRLY1. The results show that WHIRLY1 knockdown sets in motion a delay in senescence that involves all aspects of gene expression, including changes in chromatin structure.
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