How does auxin turn on genes?
How does auxin turn on genes?
复制标题
DOI：
10.1104/pp.118.2.341
复制
发表时间：
1998-10-01
期刊：
影响因子：
7.4
通讯作者：
Murfett, J
中科院分区：
文献类型：
--
作者：
Guilfoyle, T;Hagen, G;Murfett, J
植物激素生长素(或IAA)在多种生长发育过程中起着关键作用。在细胞水平上，生长素在植物生命周期中作为分裂、延伸和分化的信号。在全植物水平上，生长素在根的形成、顶端优势、向向性和衰老过程中起着重要作用。问题是，这样一个简单的分子如何调节植物细胞、组织和器官中如此多的反应？这个问题的答案需要了解生长素的感知、信号转导和基因调控。目前，生长素是如何被植物细胞识别为一种激素的，或者是什么受体分子参与了这种识别，人们还知之甚少。虽然已经鉴定和鉴定了几类生长素结合蛋白(见Napier和Venis，1995)，但尚不清楚这些蛋白中的哪一类在信号转导通路中作为受体发挥作用，这些信号转导通路靶向于细胞核并调节生长素反应基因的表达。同样，生长素信号转导途径参与早期生长素调控的基因表达目前仍是一个谜。植物细胞中可能存在一种或几种生长素受体和生长素信号转导途径，而且这些受体和途径在不同细胞类型和组织中的分布并不均匀。多种类型的生长素受体和信号转导途径可以解释不同组织和器官中观察到的以不同方式响应生长素的多样性。无论是哪种生长素受体和信号转导途径，很明显，外源应用生长素可以迅速和特异性地改变不同组织和器官中选定基因的表达。基因表达水平的反应最早可以在生长素应用后2到3分钟被检测到(参见Guilfoyle，1998)，在这一短时间内被激活或抑制的基因被称为初级或早期生长素响应基因，其中许多基因已经被识别和表征。这些基因及其表达已经在最近的综述中讨论过(Abel和Theologis，1996；Guilfoyle，1998)，这里不再详细说明。这一更新集中在顺式作用元件(即赋予启动子生长素响应性的DNA序列)和反式作用因子(即结合顺式作用元件的转录因子)上。
The plant hormone auxin (or IAA) plays a key role in a wide variety of growth and developmental processes. At the cellular level, auxin acts as a signal for division, extension, and differentiation during the course of the plant life cycle. At the whole-plant level, auxin plays an important role in root formation, apical dominance, tropism, and senescence. The question is how does such a simple molecule regulate such a plethora of responses within an assortment of cells, tissues, and organs of plants? The answer to this question requires an understanding of auxin perception, signal transduction, and gene regulation. At this time, little is known about how auxin is recognized as a hormone by plant cells or what receptor molecules are involved in this recognition. Although several classes of auxin-binding proteins have been identified and characterized (for review, see Napier and Venis, 1995), it is not clear which if any of these function as receptors in signal transduction pathways that target the nucleus and regulate auxin-responsive gene expression. Likewise, the auxin signal transduction pathway involved in early auxinregulated gene expression is currently a mystery. It is possible that one or several classes of auxin receptors and auxin signal transduction pathways exist in plant cells, and that these receptors and pathways are not uniformly distributed among different cell types and tissues. Multiple types of auxin receptors and signal transduction pathways could account for some of the diversity observed in different tissues and organs that respond to auxin in a variety of ways.Whatever the auxin receptors and signal transduction pathways, it is clear that exogenously applied auxin can rapidly and specifically alter the expression of selected genes in different tissues and organs. Responses at the gene-expression level can be detected as early as 2 to 3 min after auxin application (for review, see Guilfoyle, 1998), and genes that are activated or repressed in this brief time are referred to as primary or early auxin-responsive genes, a number of which have been identified and characterized. These genes and their expression have been discussed in recent reviews (Abel and Theologis, 1996; Guilfoyle, 1998) and will not be elaborated on here. This Update focuses on cis-acting elements (ie DNA sequences that confer auxin responsiveness to a promoter) and trans-acting factors (ie transcription factors that bind to the cis-acting elements)