Defining the symbiotic calcium channel of legumes

细胞有能力识别一系列广泛的信号分子，这种识别对于多细胞生物体的协调发展至关重要。钙通常被用作第二信使，允许识别信号，例如在细胞表面，将其传递到细胞的其他区域，例如发生基因调控的细胞核。钙作为信号分子的效力，以及细胞质中持续的钙水平是有毒的，这意味着钙水平受到严格的调控。钙要么被泵出细胞外，要么被泵入细胞内的隔室，如内质网、液泡和小泡。钙离子释放到胞浆中起信号作用的是钙离子通道的功能，这些钙离子通道位于这些隔室的膜上，并允许钙以其浓度梯度流入细胞质或核质。作为钙通道的蛋白质在动物系统中已被广泛研究，许多通道复合体已被证明调节钙。许多动物钙通道在植物中不存在，这阻碍了植物系统中钙信号的特征。负责调节植物细胞中钙的蛋白质才刚刚开始被发现。在这项提案中，我们将定义在豆科植物共生信号通路中发生钙振荡的钙通道。这一信号通路负责建立固氮细菌协会以及豆科植物根部发生的有益真菌协会。我们已经确定了共生钙通道的有力候选者，在本提案中，我们将进一步验证该候选钙通道在共生信号中的作用，并定义可能驻留在核膜上的通道复合体的成分。

Cells have the capacity to recognise a wide array of signalling molecules and such recognition is essential to allow coordinated development in multicellular organisms. Calcium is commonly used as a secondary messenger that allows the recognition of a signal, for instance on the cell surface, to be transmitted to other regions of the cell, for instance the nucleus where gene regulation occurs. The potency of calcium as a signalling molecule and the fact that sustained calcium levels in the cytoplasm are toxic, means that calcium levels are tightly regulated. Calcium is either pumped outside the cell or into intracellular compartments such as the endoplasmic reticulum, the vacuole and vesicles. The release of calcium into the cytosol to act in signalling is the function of calcium channels that reside on the membranes of these compartments and allow the flow of calcium with its concentration gradient into the cytoplasm or nucleoplasm. Proteins that function as calcium channels have been extensively studied in animal systems and a number of channel complexes have been shown to regulate calcium. Many of the animal calcium channels are absent in plants and this has hindered the characterisation of calcium signalling in plant systems. The proteins responsible for regulation of calcium in plant cells are only just beginning to be discovered. In this proposal we will define the calcium channels responsible for calcium oscillations that occur in the symbiosis signalling pathway of legumes. This signalling pathway is responsible for the establishment of nitrogen-fixing bacterial associations as well as beneficial fungal associations that occur in legume roots. We have already identified a strong candidate for the symbiotic calcium channel and in this proposal we will further validate the role of this candidate calcium channel in symbiosis signalling, as well as define the components of the channel complex that is likely to reside on the nuclear membranes.