Functions of the Whirly 1 protein in chloroplast-nucleus crosstalk

随着世界人口的增长，我们将在未来四十年面临70%的粮食需求增长，很明显，优化植物生产力的需求是我们这个时代最重要的问题之一。植物利用被称为光合作用的过程来获取光能，并将其转化为化学能，用于生长，并产生储存碳水化合物和各种其他化合物。光合作用过程被安置在称为叶绿体的亚细胞隔间中。与移动的动物不同，无根植物没有能力离开不利的环境条件，因此进化出了识别和应对环境变化的广泛能力。叶绿体是这种变化的主要传感器，尤其是光的可用性和质量，它们将信息传递给细胞核，以调节基因表达，以便在广泛的条件下进行适当的调整，以优化光合作用过程。叶绿体到细胞核的信号通路不仅可以实现光合作用的持续驯化，还可以协调调节光合作用、生长和防御功能。虽然叶绿体到细胞核的信号传导现象已经被发现了30多年，但对其所涉及的机制或不同的途径成分知之甚少。在光合作用过程中，光能被用来将水分解成氢和氧的组成部分，释放出电子，然后通过光合作用电子传递链产生固定二氧化碳所需的能量。获得电子的光合成分被描述为还原，失去电子的光合成分被描述为氧化，这些概念一起描述了光合成分的还原/氧化（氧化还原）还原/氧化（氧化还原）状态。目前的概念表明，监测PET链的氧化还原状态是一种重要的传感/信号机制，但我们对如何利用这种机制将信息传递到细胞核缺乏清楚的了解。植物拥有一个叫做WHIRLY的DNA结合蛋白小家族。在模式植物拟南芥（Arabidopsis thaliana）中，两个WHIRLY蛋白（WHIRLY1和3）是针对叶绿体的，但WHIRLY1也存在于细胞核中。大麦也有一个位于叶绿体和细胞核中的WHIRLY1蛋白。该项目将验证以下假设，即WHIRLY1参与叶绿体到细胞核的信号传导，特别是受叶绿体氧化还原信号的调节，特别是光合电子传递途径产生的氧化还原信号，从而改变WHIRLY1的位置及其DNA结合特性，从而调节基因表达。这些研究的愿景是更好地理解叶绿体的传感器作用，特别是WHIRLY1在基因表达调控中的核心作用，以及更深入地了解如何利用这种整合在最佳和逆境条件下最大化植物生产力。

As the world population grows and we are facing a 70% increase of food demand over the next four decades, it is clear that the need to optimize plant productivity is one of the most important issues of our time. Plants use the process called photosynthesis, to harvest light energy and convert it into chemical energy that can be used for growth and to produce storage carbohydrates, and a wide range of other compounds. The photosynthetic processes are housed in sub-cellular compartments called chloroplasts. Unlike mobile animals, sessile plants do not have the capacity to move away from adverse environmental conditions and have therefore evolved an extensive capacity to recognise and respond to environmental changes. Chloroplasts are major sensors of such changes, particularly the availability and quality of light and they this transmit information to the nucleus in order regulate gene expression, so that appropriate adjustments can be made to optimise photosynthetic processes over a wide range of conditions. Chloroplast-to-nucleus signalling pathways not only allow the continuous acclimation of photosynthesis but also the coordinated regulation of photosynthesis, growth and defence functions. While the phenomenon of chloroplast to nucleus signalling has been known for over 30 years, very little is known about the mechanisms involved or the different pathway components. During the process of photosynthesis light energy is used to split water into its component parts of hydrogen and oxygen with the release of electrons which are then passed down the photosynthetic electron transport (PET) chain to generate the power required to fix CO2. A photosynthetic component that gains electrons is described as reduced while one that loses electrons is described as oxidised and together these concepts describe the reduction/oxidation (redox) reduction/oxidation (redox) status of photosynthetic components. Current concepts suggest that monitoring of the redox status of the PET chain is an important sensing/signalling mechanism but we lack a clear understanding of how this mechanism is used to transmit information to the nucleus. Plants possess a small family of DNA binding proteins, called WHIRLY. In the model plant Arabidopsis thaliana, two WHIRLY proteins (WHIRLY1 and 3) are targeted to chloroplasts, but WHIRLY1 is also found in the nucleus. The crop plant barley also has a WHIRLY1 protein that is located in chloroplasts and the nucleus of the same cells. This project will test the hypothesis that WHIRLY1 is involved in chloroplast to nucleus signalling, and specifically that it is regulated by chloroplast redox signals, particularly the ones that are generated by photosynthetic electron transport pathways, in such a way as to alter both the location of WHIRLY1 and its DNA binding properties and thus regulate gene expression. The vision of these studies is to deliver an improved understanding of the sensor role of chloroplasts, particularly the central role of WHIRLY1 in the regulation of gene expression, together with a deeper knowledge of how this integration can be used to maximize plant productivity under optimal and stress conditions.