New auxin analogs with growth-promoting effects in intact plants reveal a chemical strategy to improve hormone delivery
New auxin analogs with growth-promoting effects in intact plants reveal a chemical strategy to improve hormone delivery
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DOI：
10.1073/pnas.0806324105
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发表时间：
2008-09-30
影响因子：
11.1
通讯作者：
Chory, Joanne
中科院分区：
文献类型：
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作者：
Savaldi-Goldstein, Sigal;Baiga, Thomas J.;Chory, Joanne
植物生长依赖于环境信号和植物激素信号通路的整合。在幼苗出苗期间，胚茎（下胚轴）的伸长充当光和光依赖性反应的读出器。我们筛选了10，000种化学物质，这些化学物质是外源提供给光生长的幼苗的，并确定了100种促进下胚轴伸长的化合物。值得注意的是，这些化学品的一个子集与合成的生长素，2，4-二氯苯氧基乙酸（2，4-D）和1-萘乙酸（1-NAA）具有相同的结构特征;然而，传统的生长素（例如，例如，在一个实施例中，吲哚乙酸[IAA]、2，4-D、1-NAA对下胚轴伸长无影响。我们表明，新的化合物作为“proauxins”类似于前药。我们的数据表明，这些化合物有效地扩散到下胚轴，在那里它们以不同的速率进行分裂，释放功能性生长素。为了研究这一原理，我们采用了掩蔽策略，并设计了一个pro-2，4-D。与单独的2，4-D不同，这种pro-2，4-D增强了下胚轴的伸长。我们通过表征几种生长素受体突变体的光生长下胚轴中的生长素反应，进一步证明了生长素原的效用。因此，这些新的化合物提供了一个组织以前无法获得外源性应用生长素的实验访问。我们的研究体现了化学遗传学和生化分析的综合力量，可以发现和精制在特定植物组织中具有选择活性的激素原类似物。除了这些化合物用于解决与生长素和光信号相互作用有关的问题之外，人们可以设想使用这些简单的原理以时间和空间控制的方式研究其他植物激素和小分子反应。
Plant growth depends on the integration of environmental cues and phytohormone-signaling pathways. During seedling emergence, elongation of the embryonic stem (hypocotyl) serves as a readout for light and hormone-dependent responses. We screened 10,000 chemicals provided exogenously to light-grown seedlings and identified 100 compounds that promote hypocotyl elongation. Notably, one subset of these chemicals shares structural characteristics with the synthetic auxins, 2,4-dichlorophenoxyacetic acid (2,4-D), and 1-naphthaleneacetic acid (1-NAA); however, traditional auxins (e. g., indole-3-acetic acid [IAA], 2,4-D, 1-NAA) have no effect on hypocotyl elongation. We show that the new compounds act as "proauxins'' akin to prodrugs. Our data suggest that these compounds diffuse efficiently to the hypocotyls, where they undergo cleavage at varying rates, releasing functional auxins. To investigate this principle, we applied a masking strategy and designed a pro-2,4-D. Unlike 2,4-D alone, this pro-2,4-D enhanced hypocotyl elongation. We further demonstrated the utility of the proauxins by characterizing auxin responses in light-grown hypocotyls of several auxin receptor mutants. These new compounds thus provide experimental access to a tissue previously inaccessible to exogenous application of auxins. Our studies exemplify the combined power of chemical genetics and biochemical analyses for discovering and refining prohormone analogs with selective activity in specific plant tissues. In addition to the utility of these compounds for addressing questions related to auxin and light-signaling interactions, one can envision using these simple principles to study other plant hormone and small molecule responses in temporally and spatially controlled ways.