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Gravitropic setpoint angle control in higher plants

高等植物中的向重力设定点角度控制

基本信息

批准号：
BB/N010124/1
负责人：
Stefan Kepinski
金额：
$ 61.23万
依托单位：
University of Leeds
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FN010124%2F1
关键词：
Gravitropic setpoint angle control higher

项目摘要

The overall shape of plants, the space they occupy above and below ground, is determined principally by the number, length, and angle of their branches. Interestingly, the angles at which many lateral branches grow out are set and maintained relative to gravity rather than the main root-shoot axis. These angles are known as a gravitropic setpoint angles or GSAs. Despite being a fundamental component of the wonderful variation in plant architecture observed throughout nature until recently the mechanisms underlying GSA regulation were not known. The maintenance of vertical GSAs in the main primary root-shoot axis, otherwise known as gravitropism, is well understood: displacement of the main stem or root is perceived within specialised gravity-sensing cells in roots and shoots. This leads to the active transport of a plant hormone called auxin from these cells and to the lower side of the displaced organ. In roots, auxin inhibits cell elongation, causing bending downwards to the vertical while in the shoot, auxin does the opposite, promoting upward curvature. In our previous work on GSA control we showed that the same underlying gravitropic response occurs in non-vertical root and shoot branches but is counteracted by another growth component, the antigravitropic offset. We showed that branches that are less vertical have a stronger antigravitropic offset and that the magnitude of this offset is also regulated directly within the gravity-sensing cell. We have also shown that like gravitropism, antigravitropism depends on auxin transport but in this case from the upper, rather than the lower side of the gravity-sensing cell. The molecular mechanisms underlying antigravitropic activity and how that activity is restricted to non-vertical branches is not known and is the subject of this study.The project has three parts. In the first, we focus on the regulation auxin transporters called PIN proteins that are responsible for moving auxin out of cells. In gravity-sensing cells, two particular PINs, PIN3 and PIN7, appear to mediate both gravitropic and antigravitropic auxin fluxes. The subcellular localisation and activity of PINs has been shown to be regulated by their phosphorylation. Our preliminary work has shown that a mutated phosphomimic version of PIN3 has less vertical lateral roots while a mutated PIN3 that cannot be phosphorylated has more vertical lateral roots. The simplest interpretation of these data is that unphosphorylated PINs in gravity-sensing cells contribute to downward, gravitropic auxin flux while phosphorylated PIN mediates an upward, antigravitropic flux. Importantly, while the direction of the gravitropic flux out of the gravity-sensing cells can be reset very rapidly if the plant is reorientated, our data indicate that changes in the direction of auxin fluxes that drive antigravitropic activity take much longer to be re-established. Therefore, by tracking the molecular and cell biological events within gravity-sensing cells of lateral roots undergoing simple reorientations we can observe which PINs and PIN phosphoregulators are associated with the faces of the cell that were once transporting auxin to sustain gravitropic or antigravitropic growth and then watch as the new polarities for gravi- and antigravitropic auxin fluxes are re-established.A central feature of gravitropism is that the magnitude of graviresponse increases the further an organ is moved away from the vertical. This phenomenon is crucial for GSA control and so in the second part of the project we use advanced microscopy to understand the biophysical and molecular basis of this response. In the final part of the project we will screen a collection of mutated Arabidopsis plants to look for plants with little or no non-vertical growth in lateral branches. This will allow us to identify the genes that restrict antigravitropic activity to lateral branches and allow us to form a coherent understanding of GSA control in plants.

植物的整体形状，即它们在地上和地下所占据的空间，主要由其树枝的数量、长度和角度决定。有趣的是，许多侧枝生长的角度是相对于重力而不是主根-茎轴设置和保持的。这些角度被称为向重力设定点角度或GSA。尽管GSA是整个自然界中观察到的植物结构奇妙变化的基本组成部分，但直到最近，GSA调节的潜在机制仍不清楚。在主主根-茎轴中垂直GSA的维持，也称为向重力性，是很好理解的：在根和茎中专门的重力感应细胞内感知主茎或根的位移。这导致一种叫做生长素的植物激素从这些细胞中主动运输到移位器官的下侧。在根中，生长素抑制细胞伸长，导致向下弯曲成垂直，而在芽中，生长素则相反，促进向上弯曲。在我们以前的工作GSA控制，我们表明，同样的潜在的向地性反应发生在非垂直的根和枝，但抵消了另一个增长的组成部分，反向地性偏移。我们发现，不太垂直的分支具有更强的反重力偏移，并且这种偏移的大小也直接在重力感应细胞内进行调节。我们还表明，像向重力性，反向重力性依赖于生长素的运输，但在这种情况下，从上方，而不是重力感应细胞的下侧。抗向重力活性的分子机制以及这种活性是如何被限制在非垂直分支的尚不清楚，这是本研究的主题。首先，我们重点关注称为PIN蛋白的生长素转运蛋白的调节，该蛋白负责将生长素移出细胞。在重力感应细胞中，两个特殊的PIN，PIN 3和PIN 7，似乎介导向重力和反向重力生长素通量。PIN的亚细胞定位和活性已被证明受其磷酸化调节。我们的初步工作表明，突变的拟磷酸化形式的PIN 3具有较少的垂直侧根，而不能磷酸化的突变的PIN 3具有更多的垂直侧根。这些数据的最简单的解释是，未磷酸化的PIN在重力感应细胞有助于向下，向重力生长素流量，而磷酸化的PIN介导向上，antigravitropic流量。重要的是，虽然重力感应细胞的向重力通量的方向可以非常迅速地重置，如果植物被重新定位，我们的数据表明，生长素通量的方向的变化，驱动反向重力活动需要更长的时间才能重新建立。因此，我们认为，通过跟踪侧根重力感应细胞内的分子和细胞生物学事件，我们可以观察到哪些PIN和PIN磷酸调节剂与曾经运输生长素以维持向重力或反向重力生长的细胞表面相关，然后观察向重力和反向重力生长素通量的新极性被重新定位。向重力性的一个中心特征是，器官离垂直方向越远，重力反应的幅度就越大。这种现象对于GSA控制至关重要，因此在该项目的第二部分，我们使用先进的显微镜来了解这种反应的生物物理和分子基础。在项目的最后一部分，我们将筛选一批突变的拟南芥植物，以寻找侧枝几乎没有或没有非垂直生长的植物。这将使我们能够确定限制侧枝抗重力活性的基因，并使我们能够对植物中的GSA控制形成一致的理解。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Auxin in Root Development.

DOI：
10.1101/cshperspect.a039933
发表时间：
2021-07
期刊：
Cold Spring Harbor perspectives in biology
影响因子：
7.2
作者：
Suruchi Roychoudhry;S. Kepinski
通讯作者：
Suruchi Roychoudhry;S. Kepinski

The Tetrazole Analogue of the Auxin Indole-3-acetic Acid Binds Preferentially to TIR1 and Not AFB5.

生长素吲哚-3-乙酸的四唑类似物优先与 TIR1 结合，而不与 AFB5 结合。

DOI：
10.1021/acschembio.8b00527
发表时间：
2018
期刊：
ACS chemical biology
影响因子：
4
作者：
Quareshy M
通讯作者：
Quareshy M

Rice actin binding protein RMD controls crown root angle in response to external phosphate.

水稻肌动蛋白结合蛋白 RMD 响应外部磷酸盐控制冠根角度

DOI：
10.1038/s41467-018-04710-x
发表时间：
2018-06-11
期刊：
Nature communications
影响因子：
16.6
作者：
Huang G;Liang W;Sturrock CJ;Pandey BK;Giri J;Mairhofer S;Wang D;Muller L;Tan H;York LM;Yang J;Song Y;Kim YJ;Qiao Y;Xu J;Kepinski S;Bennett MJ;Zhang D
通讯作者：
Zhang D

The developmental and environmental regulation of gravitropic setpoint angle in Arabidopsis and bean.