Seed germination control through mitochondrial thiol switches

种子是我们的主要食物来源。对于植物，种子允许长距离和长时间的繁殖，并保护后代免受不利环境的影响，如寒冷或干旱。种子能将预先形成的胚保持在静止状态，并在条件适宜时迅速重新激活胚，这种非凡的能力是高等植物所独有的。在萌发过程中，胚胎依赖于种子内的能量储存。它们快速动员以提供细胞有效萌发所需的ATP，这在很大程度上取决于线粒体。虽然线粒体代谢在静止期必须在很大程度上不活跃以保存资源，但在吸胀时萌发的激活需要急剧而快速的启动。作为这一唤醒的一部分，许多蛋白质巯基开关被快速操作，发芽效率取决于线粒体谷胱甘肽和硫氧还蛋白机制。在这个项目中，我们的目标是解剖的特异性和不同的线粒体巯基开关在控制和支持萌发的拟南芥的调控意义。在完整的种子，胚胎和纯化的线粒体中的亚细胞氧化还原和能量生理学的定制的原位传感设置将允许监测硫醇氧化还原状态的快速转变及其与细胞能量生理学的串扰。感测将告知最先进的定量硫醇氧化还原蛋白质组学，以阐明在内源性热力学和动力学约束下操作的各个靶蛋白硫醇开关的身份和特异性。将使用靶向半胱氨酸诱变、计算机相互作用建模以及呼吸、代谢和蛋白质生化分析来剖析其个体调控意义和特异性。线粒体巯基开关的操作对种子活力和萌发控制的影响将在种子休眠和老化的背景下进行研究。因此，这项工作将阐明线粒体巯基开关作为萌发控制的上游机制的意义。

Seeds are our main food source. For plants, seeds allow propagation over long distances and time periods, and provide protection of progeny from hostile environments, such as cold or drought. The remarkable ability of a seed to preserve a preformed embryo in a quiescent state and to rapidly re-activate it when the conditions are favourable is unique to higher plants. During germination the embryo relies on the energy stores within the seed. Their rapid mobilization to provide the ATP that the cells require for efficient germination is critically dependent on the mitochondria. While mitochondrial metabolism has to be largely inactive during quiescence to preserve resources, activation of germination at imbibition necessitates a sharp and rapid kick-start. As part of this wakeup call, numerous protein thiol switches are rapidly operated and germination efficiency depends on the mitochondrial glutathione and thioredoxin machineries. In this project we aim to dissect the specificity and regulatory significance of different mitochondrial thiol switches in controlling and supporting germination of Arabidopsis thaliana. A tailored in situ sensing setup for subcellular redox and energy physiology in intact seeds, embryos and purified mitochondria will allow to monitor the rapid transition in thiol redox status and its crosstalk with cellular energy physiology. Sensing will inform state-of-the-art quantitative thiol redox proteomics to elucidate the identity and specificity of the individual target protein thiol switches, which are operated under the endogenous thermodynamic and kinetic constraints. Their individual regulatory significance and specificity will be dissected using targeted cysteine mutagenesis, in silico interaction modelling, as well as respiratory, metabolic and protein biochemical analyses. The implications that operation of mitochondrial thiol switches has on seed vigour and germination control will be investigated in the context of seed dormancy and aging. As such this work will elucidate the significance of mitochondrial thiol switching as an upstream mechanism of germination control.