The role of cyclic nucleotides in stomatal responses to environmental signals

过去40年进行的实验表明，环核苷酸在植物细胞信号传导中发挥作用。然而，负责调节氯化萘水平和对氯化萘浓度变化作出反应的植物信号系统的确切性质尚不清楚。我们确实知道，CN信号转导inplants是不同的典型系统中遇到的哺乳动物，因为没有高等植物基因组已被证明含有cAMP激活的蛋白激酶A或PKG的cGMP调制。然而，植物确实包含CN调节离子通道的大家族。另一个主要问题是缺乏氯化萘调节的磷酸二酯酶（cnPDE）。在最近的一项突破性进展中（未发表），我们利用先进的生物信息学鉴定了一个编码具有cGMP PDE活性的蛋白质（AtPDE 1）的拟南芥基因。我们的分析表明，该基因起源于细菌，在植物基因组中以单拷贝基因形式保留，但在动物谱系中丢失。这表明动物和植物CN信号传导之间存在显着差异。由尼克·斯米尔诺夫教授（埃克塞特）和克里·富兰克林教授（布里斯托）共同监督是为了充分阐明该基因在保卫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，它参与光和阿坝介导的气孔反应。本研究的工作将包括使用一种新型的单细胞cGMP传感器（FlincG）来研究保卫细胞中cGMP水平是否在响应光阿坝和CO2时被调节。学生还将通过使用气体交换，生物测定技术和原子力显微镜（与Merv Miles FRS教授，物理学）来监测突变体中的气孔反应，从而充分研究PDE 1基因在拟南芥中的作用。我们将使用转录组学研究GMP基因调控网络中涉及的其他基因，并使用CRISPR-Cas9（与K Edwards教授和Gary Barker，生物学）来操纵小麦中PDE 1的表达，随后表征其对水分利用效率的影响。学生将获得成像，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的全面培训。

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 In a recent breakthrough(unpublished) we have used advanced bioinformatics to identify an Arabidopsis gene that encodes aprotein with cGMP PDE activity (AtPDE1).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 Our unpublished data suggest that it is involved in light and ABA mediatedstomatal responses.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.