Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Korea.
Department of Functional Genomics, KRIBB School of Bioscience, University of Science and Technology, Daejeon, 34113, Korea.
New Phytol. 2020 Feb;225(3):1285-1296. doi: 10.1111/nph.16076. Epub 2019 Aug 16.
Plants sense mechanical stimuli to recognise nearby obstacles and change their growth patterns to adapt to the surrounding environment. When roots encounter an obstacle, they rapidly bend away from the impenetrable surface and find the edge of the barrier. However, the molecular mechanisms underlying root-obstacle avoidance are largely unknown. Here, we demonstrate that PIN-FORMED (PIN)-mediated polar auxin transport facilitates root bending during obstacle avoidance. We analysed two types of bending after roots touched barriers. In auxin receptor mutants, the rate of root movement during first bending was largely delayed. Gravity-oriented second bending was also disturbed in these mutants. The reporter assays showed that asymmetrical auxin responses occurred in the roots during obstacle avoidance. Pharmacological analysis suggested that polar auxin transport mediates local auxin accumulation. We found that PINs are required for auxin-assisted root bending during obstacle avoidance. We propose that rapid root movement during obstacle avoidance is not just a passive but an active bending completed through polar auxin transport. Our findings suggest that auxin plays a role in thigmotropism during plant-obstacle interactions.
植物能够感知机械刺激，识别附近的障碍物，并改变生长模式以适应周围环境。当根遇到障碍物时，它们会迅速从不可穿透的表面弯曲，并找到障碍物的边缘。然而，根避障的分子机制在很大程度上尚不清楚。在这里，我们证明了 PIN 形成（PIN）介导的极性生长素运输有助于根在避障过程中的弯曲。我们分析了根接触障碍物后的两种弯曲类型。在生长素受体突变体中，第一次弯曲过程中根的移动速度大大延迟。在这些突变体中，重力导向的第二次弯曲也受到干扰。报告基因检测表明，在避障过程中，根中会发生不对称的生长素响应。药理学分析表明，极性生长素运输介导了局部生长素的积累。我们发现，PIN 对于避障过程中生长素辅助的根弯曲是必需的。我们提出，避障过程中快速的根移动不仅是被动的，而且是通过极性生长素运输完成的主动弯曲。我们的研究结果表明，生长素在植物与障碍物相互作用过程中的向触性中发挥作用。
