PDF(Pubmed)
Abstract：
Plant roots sense many physical and chemical cues in soil, such as gravity, humidity, light, and chemical gradients, and respond by redirecting their growth toward or away from the source of the stimulus. This process is called tropism. While gravitropism is the tendency to follow the gravitational field downwards, electrotropism is the alignment of growth with external electric fields and the induced ionic currents. Although root tropisms are at the core of their ability to explore large volumes of soil in search of water and nutrients, the molecular and physical mechanisms underlying most of them remain poorly understood. We have previously provided a quantitative characterization of root electrotropism in Arabidopsis (Arabidopsis thaliana) primary roots exposed for 5 h to weak electric fields, showing that auxin asymmetric distribution is not necessary for root electrotropism but that cytokinin biosynthesis is. Here, we extend that study showing that long-term electrotropism is characterized by a complex behavior. We describe overshoot and habituation as key traits of long-term root electrotropism in Arabidopsis and provide quantitative data about the role of past exposures in the response to electric fields (hysteresis). On the molecular side, we show that cytokinin, although necessary for root electrotropism, is not asymmetrically distributed during the bending. Overall, the data presented here represent a step forward toward a better understanding of the complexity of root behavior and provide a quantitative platform for future studies on the molecular mechanisms of electrotropism.
摘要：
植物的根感知土壤中的许多物理和化学线索，比如重力，湿度,湿度光,和化学梯度，并通过将他们的增长转向刺激源或远离刺激源做出回应。这个过程被称为向性。虽然引力是跟随引力场向下的趋势，趋电性是生长与外部电场和感应离子电流的对准。尽管根的向性是他们探索大量土壤以寻找水和养分的能力的核心，它们中大多数的分子和物理机制仍然知之甚少。我们以前已经提供了拟南芥（拟南芥）初根暴露于弱电场5小时的根系嗜电的定量表征，表明生长素的不对称分布对于根的电化不是必需的，但是细胞分裂素的生物合成是必需的。这里,我们扩展了这项研究，表明长期的电向性特征是复杂的行为。我们将过冲和习惯性描述为拟南芥长期根系嗜电的关键特征，并提供了有关过去暴露在电场（滞后）响应中的作用的定量数据。在分子方面，我们发现细胞分裂素,虽然是根向电性所必需的，在弯曲过程中不对称分布。总的来说,这里提供的数据代表了朝着更好地理解根行为的复杂性迈出的一步，并为未来研究电子取向的分子机制提供了定量平台。
