Nuclear calcium regulation of plant development

钙信号对于植物和动物的生长和发育都是必不可少的。在动物中，核钙释放是神经元基因表达和细胞增殖的有效调节剂。核钙信号也被认为是必不可少的豆科植物，以促进协会与固氮细菌和磷酸盐提供丛枝菌根真菌。豆类是世界上最重要的农业粮食作物之一，有益于全世界数十亿农民和消费者，并提供了有机氮化合物天然土壤富集的重要方面。植物核钙信号的机制知之甚少。在我的工作中，我使用了豆科植物中的共生协会作为一个平台来剖析植物核钙信号。使用广泛的方法，我发现了一些离子通道位于核膜负责共生核钙释放。其中，本人首次定义了植物核相关的环核苷酸门控钙通道（CNGC 15）。CNCG 15位于核膜上，与钾离子渗透通道（DMI 1）形成复合物，也是共生核钙信号产生所必需的。有趣的是，CNGC 15和DMI 1在所有陆地植物中都是保守的，包括非共生物种，这强烈表明它们在植物发育过程中具有其他功能。与此一致，我发现了许多缺陷，在拟南芥品系突变CNGC 15和DMI 1，其中包括根发育缺陷。我认为我在豆类植物中的研究揭示了参与调节细胞核钙释放的一般植物机制。通过研究调节核钙释放的成分，我将能够了解何时何地核钙信号是重要的。我的建议将集中在核钙信号在根发育过程中的作用，根生长和共生微生物的协会。与CNGC 15和DMI 1在根发育中的功能一致，我观察到拟南芥根分生组织细胞对植物激素生长素和细胞分裂素的反应过程中的核钙反应。这些钙的反应是机械不同的细胞核中观察到的豆类钙信号在共生协会。我的研究整合了分子生物学，遗传学，细胞生物学，化学，电生理学和数学建模，以研究CNGC 15-DMI 1如何调节核钙释放，从而导致植物发育过程。它将使用大量的拟南芥突变体和转基因株系，我已经产生了，与一个面板的核钙传感器允许检测核钙信号在拟南芥突变体阵列。我的工作将剖析核钙信号在根发育过程中发挥的作用，以及如何不同的核钙信号编码。最后，通过转录组学和突变体筛选相结合，我将独特地准备破译与根发育过程中的核钙信号相关的下游信号成分。

Calcium signalling is essential for growth and development, in both plants and animals. In animals nuclear calcium release is a potent regulator of neuronal gene expression and of cell proliferation. Nuclear calcium signalling is also known to be essential in legumes to promote associations with nitrogen fixing bacteria and phosphate delivering arbuscular mycorrhizal fungi. Legumes are among the world's most important agricultural food crops that are beneficial to billions of farmers and consumers worldwide and provide an essential aspect of natural soil enrichment of organic nitrogen compounds. The mechanisms of plant nuclear calcium signalling were poorly understood. During my work I have used the symbiotic associations in legumes as a platform to dissect plant nuclear calcium signalling. Using a wide range of approaches, I discovered a number of ion channels located at the nuclear envelope that are responsible for symbiotic nuclear calcium release. Among them, I defined the first plant nuclear-associated calcium channels encoded by cyclic nucleotide gated channels (CNGC15s). The CNCG15s sit at the nuclear envelope in a complex with a potassium permeable channel (DMI1), also required for the generation of the symbiotic nuclear calcium signals. Interestingly, CNGC15s and DMI1 are conserved across all land plants, including non-symbiotic species, strongly suggesting that they have other functions during plant development. Consistent with this I have found a number of defects in Arabidopsis lines mutated in CNGC15 and DMI1, that include root developmental defects. I propose that my research in legumes has revealed the generic plant machinery involved in the regulation of nuclear calcium release. By studying the components that regulate nuclear calcium release I will be able to understand when and where nuclear calcium signalling is important. My proposal will focus on the role of nuclear calcium signalling during root development, both root growth and associations with symbiotic microorganisms. Consistent with a function for CNGC15 and DMI1 in root development I have observed nuclear calcium responses in Arabidopsis root meristematic cells during their response to the phytohormones auxin and cytokinin. These calcium responses are mechanistically different from the nuclear calcium signals observed in legumes during symbiotic associations. My proposed research integrates molecular biology, genetics, cell biology, chemistry, electrophysiology and mathematical modelling to investigate how CNGC15-DMI1 regulates nuclear calcium release leading to plant developmental processes. It will use a large collection of Arabidopsis mutant and transgenic lines, that I have already generated, with a panel of nuclear calcium sensors allowing detection of nuclear calcium signals in an array of Arabidopsis mutants. My work will dissect the functions that nuclear calcium signalling plays in root developmental processes and how diverse nuclear calcium signals are encoded. Finally, through a combination of transcriptomics and mutant screens, I will be uniquely poised to decipher the downstream signalling components associated with nuclear calcium signalling during root development.