Defining the symbiotic calcium channel of legumes

细胞具有识别多种信号分子的能力，这种识别对于多细胞生物体的协调发育至关重要。钙通常用作第二信使，其允许识别信号，例如在细胞表面上，以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一事实意味着钙水平受到严格调节。钙被泵出细胞外或进入细胞内区室，如内质网、液泡和小泡。钙释放到胞质溶胶中以在信号传导中起作用是钙通道的功能，所述钙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中。作为钙通道的蛋白质在动物系统中已被广泛研究，并且许多通道复合物已被证明可调节钙。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表征。负责调节植物细胞中钙的蛋白质才刚刚开始被发现。在这个建议中，我们将定义负责钙振荡发生在共生信号通路的豆类钙通道。这一信号通路负责建立固氮细菌协会以及有益的真菌协会，发生在豆科植物的根。我们已经确定了共生钙通道的一个强有力的候选者，在本提案中，我们将进一步验证该候选钙通道在共生信号传导中的作用，并定义可能存在于核膜上的通道复合物的组分。

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.