Evans Matthew J, Morris Richard J
Computational and Systems Biology, Crop Genetics, John Innes Centre, Colney Lane, Norwich, NR4 7UH, UK.
Plant J. 2017 Sep;91(6):1029-1037. doi: 10.1111/tpj.13624. Epub 2017 Aug 10.
Long-distance signalling is important for coordinating plant responses to the environment. Variation potentials (VPs) are a type of long-distance electrical signal that are generated in plants in response to wounding or flaming. Unlike self-propagating action potentials, VPs can be measured beyond regions of dead or chemically treated tissue that block signal generation, suggesting a different mode of propagation. Two alternative propagation mechanisms have been proposed: movement of a chemical agent and a pressure wave through the vasculature. Variants of these two signalling mechanisms have been suggested. Here, we use simple models of the underlying physical processes to evaluate and compare these predictions against independent data. Our models suggest that chemical diffusion and pressure waves are unlikely to capture existing data with parameters that are known from other sources. The previously discarded hypothesis of mass flow in the xylem transporting a chemical agent, however, is able to reproduce experimental propagation speeds for VPs. We therefore suggest that chemical agents transported by mass flow within the xylem are more likely than a pressure wave or chemical diffusion as a VP propagation mechanism. Understanding this mode of long-distance signalling within plants is important for unravelling how plants coordinate physiological responses via cell-to-cell communication.
长距离信号传导对于协调植物对环境的反应至关重要。变异电位（VPs）是一种长距离电信号，植物在受到创伤或火烧时会产生这种信号。与自我传播的动作电位不同，变异电位可以在死亡或经过化学处理的组织区域之外进行测量，这些区域会阻止信号产生，这表明其传播方式不同。已经提出了两种替代的传播机制：一种化学物质的移动以及通过脉管系统的压力波。这两种信号传导机制的变体也已被提出。在这里，我们使用基础物理过程的简单模型来评估这些预测，并将其与独立数据进行比较。我们的模型表明，化学扩散和压力波不太可能用从其他来源已知的参数来解释现有数据。然而，先前被摒弃的关于木质部中物质流运输化学物质的假设，能够重现变异电位的实验传播速度。因此，我们认为，通过木质部内物质流运输的化学物质作为变异电位传播机制比压力波或化学扩散更有可能。了解植物体内这种长距离信号传导模式对于揭示植物如何通过细胞间通讯协调生理反应至关重要。
