Seed germination in presence and absence of histone deaceatylase inhibitor, Trichostain A (TSA).

Histone acetylation is involved in the regulation of gene expression in plants and eukaryotes. Histone deacetylases (HDACs) are enzymes that catalyze the removal of acetyl groups from histones, which is associated with the repression of gene expression. To study the role of histone acetylation in the regulation of gene expression during seed germination, trichostatin A (TSA), a specific inhibitor of histone deacetylase, was used to treat imbibing Arabidopsis thaliana seeds. GeneChip arrays were used to show that TSA induces up-regulation of 45 genes and down-regulation of 27 genes during seed germination. Eight TSA-up-regulated genes were selected for further analysis - RAB18, RD29B, ATEM1, HSP70 and four late embryogenesis abundant protein genes (LEA). A gene expression time course shows that these eight genes are expressed at high levels in the dry seed and repressed upon seed imbibition at an exponential rate. In the presence of TSA, the onset of repression of the eight genes is not affected but the final level of repressed expression is elevated. Chromatin immunoprecipitation and HDAC assays show that there is a transient histone deacetylation event during seed germination at one day after imbibition, which serves as a key developmental signal that affects the repression of the eight genes. Keywords: histone deacetylase inbibition, developmental effects Three samples: Unimbibed seeds, untreated imbibed seeds, TSA-treated imbibed seeds.

组蛋白乙酰化（Histone acetylation）参与植物及真核生物的基因表达调控。组蛋白去乙酰化酶（Histone deacetylases, HDACs）是一类催化组蛋白乙酰基移除的酶，其功能与基因表达的抑制相关。为探究组蛋白乙酰化在种子萌发过程中基因表达调控的作用，本研究使用组蛋白去乙酰化酶特异性抑制剂曲古抑菌素A（trichostatin A, TSA）处理吸胀状态的拟南芥（Arabidopsis thaliana）种子。通过基因芯片（GeneChip）阵列分析发现，在种子萌发阶段，TSA可诱导45个基因上调表达、27个基因下调表达。研究选取了8个受TSA上调的基因进行后续分析：RAB18、RD29B、ATEM1、HSP70以及4个胚胎发育晚期丰富蛋白基因（late embryogenesis abundant protein genes, LEA）。基因表达时序分析结果显示，这8个基因在干燥种子中呈高表达状态，且在种子吸胀过程中以指数速率被抑制表达。在TSA处理条件下，这8个基因的表达抑制起始时间未受影响，但最终的抑制表达水平有所升高。染色质免疫共沉淀（Chromatin immunoprecipitation）及组蛋白去乙酰化酶活性检测结果显示，在种子吸胀后1天的萌发阶段存在一过性的组蛋白去乙酰化事件，该事件作为关键发育信号参与调控上述8个基因的表达抑制。关键词：组蛋白去乙酰化酶抑制、发育调控效应 共设置3组样本：未吸胀种子、未处理吸胀种子、TSA处理吸胀种子。