The role of cyclic nucleotides in stomatal responses to environmental signals

在过去的40年里进行的实验表明环核苷酸（CNs）在植物细胞信号传导中的作用。然而，负责调节CN水平和响应CN浓度变化的植物信号系统的确切性质尚不清楚。我们确实知道，植物体内的CN信号与哺乳动物体内的典型系统不同，因为没有高等植物基因组被证明含有cAMP激活的蛋白激酶A或由cgmp调节的PKG。然而，植物中确实含有一大家族的碳离子调节离子通道。另一个主要问题是缺乏CN调节磷酸二酯酶（cnPDE）。在最近的一项突破（未发表）中，我们使用先进的生物信息学鉴定了一个拟南芥基因，该基因编码具有cGMP PDE活性的蛋白（AtPDE1）。我们的分析表明，该基因起源于细菌，并在植物基因组中保留为单拷贝基因，但在动物谱系中丢失。这表明动物和植物的CN信号之间存在显著差异。由尼克·斯米尔诺夫教授（埃克塞特大学）和克里·富兰克林教授（布里斯托尔大学）共同监督的这个学生项目的目标是全面描述该基因在保护细胞信号传导中的作用，并确定其在作物水分利用效率中的作用。我们未发表的数据表明它参与了光和ABA介导的气孔反应。学生的工作将包括使用一种新的单细胞cGMP传感器（FlincG）研究cGMP水平是否在保护细胞中响应光ABA和CO2而被调节。该学生还将利用气体交换、生物测定技术和原子力显微镜（与Merv Miles FRS教授一起，物理学）监测突变体的气孔反应，充分表征PDE1基因在拟南芥中的作用。我们将使用转录组学研究参与gmp基因调控网络的其他基因，并使用CRISPR-Cas9（与生物学教授K Edwards和gary Barker合作）来操纵小麦中PDE1的表达，并随后表征其对水分利用效率的影响。学生将在成像、植物细胞和分子生理学、基因操作和用于研究气孔行为的技术方面获得全面的培训。

Experiments conducted over the last 40 years suggest a role for cyclic nucleotides (CNs) in plant cellsignalling. However, the precise nature of the plant signalling system responsible for modulating CNlevels and responding to changes in CN concentration is not clear. We do know that CN signalling inplants is different to the canonical system encountered in mammals because no higher plant genomehas been shown to contain either the cAMP activated protein kinase A or PKG that is modulated bycGMP. However plants do contain a large family on CN-modulated ion channels. Another major issuehas been the lack of a CN modulated phosphodiesterase (cnPDE). In a recent breakthrough(unpublished) we have used advanced bioinformatics to identify an Arabidopsis gene that encodes aprotein with cGMP PDE activity (AtPDE1). Our analyses reveal that this gene originated in bacteriaand has been retained as a single copy gene in plant genomes but has been lost from animal lineages.This suggests that there are significant differences between animal and plant CN signalling.The objective of this studentship, co-supervised by Prof Nick Smirnoff (Exeter) and Prof Kerry Franklin(Bristol) is to fully characterise the role of this gene in guard cell signalling and to determine its role incrop water use efficiency. Our unpublished data suggest that it is involved in light and ABA mediatedstomatal responses. The work in the studentship will involve investigating whether cGMP levels aremodulated in guard cells in response to light ABA and CO2 using a novel single cell cGMP sensor(FlincG). The student will also fully characterise the role of the PDE1 gene in Arabidopsis by using gasexchange, bioassay techniques and atomic force microscopy (with Prof Merv Miles FRS, Physics) tomonitor stomatal responses in the mutant. We will investigate what other genes are involved in thecGMP gene regulatory network using transcriptomics and use CRISPR-Cas9 (with Prof K Edwards andGary Barker, Biology) to manipulate the expression of PDE1 in wheat and subsequently characteriseits effect on water use efficiency. The student will gain a thorough training in imaging, plant cell andmolecular physiology, gene manipulation and techniques used to investigate stomatal behaviour.