A Nuclear Factor Regulates Abscisic Acid Responses in Arabidopsis
A Nuclear Factor Regulates Abscisic Acid Responses in Arabidopsis
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DOI：
10.1104/pp.109.144766
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发表时间：
2009-11-01
期刊：
影响因子：
7.4
通讯作者：
Schachtman, Daniel P.
中科院分区：
文献类型：
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作者：
Kim, Min Jung;Shin, Ryoung;Schachtman, Daniel P.
脱落酸（阿坝）是一种植物激素，调节植物生长以及胁迫反应。在这项研究中，我们确定并表征了一个新的拟南芥（拟南芥）蛋白，核蛋白X1（NPX 1），这是上调的压力和外源阿坝处理。气孔关闭，种子萌发和主根生长是众所周知的阿坝反应，在NPX 1过表达植物中对阿坝不太敏感。NPX 1过表达的植物更干旱敏感，响应干旱的变化是由于改变了转基因植物中的保卫细胞对阿坝的敏感性，而不是缺乏阿坝的生产。NPX 1的核定位与阿坝生物合成和阿坝信号转导相关基因的表达变化相关。为了了解NPX 1的功能，我们寻找相互作用的蛋白质，发现ABA诱导的NAC转录因子TIP与NPX 1相互作用。基于整个植物的表型，我们假设NPX 1作为一个转录抑制因子，这在酵母中得到了证实，我们发现TIP被NPX 1抑制。我们的研究结果表明，以前未知的蛋白NPX 1作为一个负调节器在植物响应环境条件的变化，通过控制ABA调节基因的表达。该因子的表征增强了我们对保卫细胞功能和植物在干旱条件下用于调节叶片失水的机制的理解。
Abscisic acid (ABA) is a plant hormone that regulates plant growth as well as stress responses. In this study, we identified and characterized a new Arabidopsis (Arabidopsis thaliana) protein, Nuclear Protein X1 (NPX1), which was up-regulated by stress and treatment with exogenous ABA. Stomatal closure, seed germination, and primary root growth are well-known ABA responses that were less sensitive to ABA in NPX1-overexpressing plants. NPX1-overexpressing plants were more drought sensitive, and the changes in response to drought were due to the altered guard cell sensitivity to ABA in transgenic plants and not to a lack of ABA production. The nuclear localization of NPX1 correlated with changes in the expression of genes involved in ABA biosynthesis and ABA signal transduction. To understand the function of NPX1, we searched for interacting proteins and found that an ABA-inducible NAC transcription factor, TIP, interacted with NPX1. Based on the whole plant phenotypes, we hypothesized that NPX1 acts as a transcriptional repressor, and this was demonstrated in yeast, where we showed that TIP was repressed by NPX1. Our results indicate that the previously unknown protein NPX1 acts as a negative regulator in plant response to changes in environmental conditions through the control of ABA-regulated gene expression. The characterization of this factor enhances our understanding of guard cell function and the mechanisms that plants use to modulate water loss from leaves under drought conditions.