Elucidating the germination transcriptional program using small molecules
Elucidating the germination transcriptional program using small molecules
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DOI：
10.1104/pp.107.110841
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发表时间：
2008-05-01
期刊：
影响因子：
7.4
通讯作者：
Cutler, Sean R.
中科院分区：
文献类型：
--
作者：
Bassel, George W.;Fung, Pauline;Cutler, Sean R.
从种子到幼苗的过渡是由发芽介导的，这是一个复杂的过程，从吸胀开始，到胚根萌发结束。为了深入了解介导萌发的转录程序，之前的研究比较了干燥、休眠和成熟后萌发的拟南芥种子的转录谱。虽然这些方法提供了信息，但它们并没有区分由抑制、代谢变化或休眠打破引起的转录反应和由萌发开始引起的转录反应。在这项研究中，利用小分子筛选方法鉴定了三种机制不同的抑制拟南芥种子萌发的小分子（甲氨蝶呤、2,4 -二硝基苯酚和环己亚胺），并用于探测萌发转录组。萌发应答转录本被定义为在所有抑制处理中与对照萌发种子相比转录本丰度显著改变的转录本，使用的数据来自ATH1微阵列。该分析确定了许多发芽调节因子，包括DELLA蛋白GAI、RGA和RGL3，脱落酸不敏感蛋白ABI4、ABI5、ABI8和FRY1，以及赤霉素受体GID1A。为了帮助可视化这些和其他公开的种子微阵列数据，我们设计了一个使用电子荧光象形文字平台的种子mRNA表达浏览器。在药物抑制的种子中，基因表达的总体下降和统计上被下调的转录本数量增加了5倍，这表明在种子萌发过程中mRNA的降解或周转发挥了作用。在我们的研究中发现的对发芽有反应的基因定义了这一过程中潜在的未被描述的调节因子，并为发芽的拟南芥种子提供了一个精细的转录特征。
The transition from seed to seedling is mediated by germination, a complex process that starts with imbibition and completes with radicle emergence. To gain insight into the transcriptional program mediating germination, previous studies have compared the transcript profiles of dry, dormant, and germinating after-ripened Arabidopsis (Arabidopsis thaliana) seeds. While informative, these approaches did not distinguish the transcriptional responses due to imbibition, shifts in metabolism, or breaking of dormancy from those triggered by the initiation of germination. In this study, three mechanistically distinct small molecules that inhibit Arabidopsis seed germination ( methotrexate, 2, 4-dinitrophenol, and cycloheximide) were identified using a small-molecule screen and used to probe the germination transcriptome. Germination-responsive transcripts were defined as those with significantly altered transcript abundance across all inhibitory treatments with respect to control germinating seeds, using data from ATH1 microarrays. This analysis identified numerous germination regulators as germination responsive, including the DELLA proteins GAI, RGA, and RGL3, the abscisic acid-insensitive proteins ABI4, ABI5, ABI8, and FRY1, and the gibberellin receptor GID1A. To help visualize these and other publicly available seed microarray data, we designed a seed mRNA expression browser using the electronic Fluorescent Pictograph platform. An overall decrease in gene expression and a 5-fold greater number of transcripts identified as statistically down-regulated in drug-inhibited seeds point to a role for mRNA degradation or turnover during seed germination. The genes identified in our study as responsive to germination define potential uncharacterized regulators of this process and provide a refined transcriptional signature for germinating Arabidopsis seeds.