Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel;
Proc Natl Acad Sci U S A. 2017 Apr 25;114(17):4549-4554. doi: 10.1073/pnas.1618584114. Epub 2017 Mar 27.
Plant roots play a dominant role in shaping the rhizosphere, the environment in which interaction with diverse microorganisms occurs. Tracking the dynamics of root-microbe interactions at high spatial resolution is currently limited because of methodological intricacy. Here, we describe a microfluidics-based approach enabling direct imaging of root-bacteria interactions in real time. The microfluidic device, which we termed tracking root interactions system (TRIS), consists of nine independent chambers that can be monitored in parallel. The principal assay reported here monitors behavior of fluorescently labeled as it colonizes the root of within the TRIS device. Our results show a distinct chemotactic behavior of toward a particular root segment, which we identify as the root elongation zone, followed by rapid colonization of that same segment over the first 6 h of root-bacteria interaction. Using dual inoculation experiments, we further show active exclusion of cells from the root surface after colonization, suggesting a possible protection mechanism against root pathogens. Furthermore, we assembled a double-channel TRIS device that allows simultaneous tracking of two root systems in one chamber and performed real-time monitoring of bacterial preference between WT and mutant root genotypes. Thus, the TRIS microfluidics device provides unique insights into the microscale microbial ecology of the complex root microenvironment and is, therefore, likely to enhance the current rate of discoveries in this momentous field of research.
植物根系在塑造根际环境中起着主导作用，根际是与各种微生物相互作用的环境。由于方法上的复杂性，目前对高空间分辨率下根系-微生物相互作用的动态进行跟踪受到限制。在这里，我们描述了一种基于微流控的方法，能够实时直接成像根系-细菌相互作用。我们称之为跟踪根系相互作用系统（TRIS）的微流控装置由九个独立的腔室组成，可以并行监测。这里报告的主要测定方法监测荧光标记的 在 TRIS 装置内定殖到 根系的过程中的行为。我们的结果表明， 对特定的根段表现出明显的趋化行为，我们将其识别为根伸长区，然后在根-细菌相互作用的前 6 小时内，该段迅速被同一段定殖。通过双接种实验，我们进一步表明， 在 定殖后， 细胞被主动排斥出根表面，这表明可能存在一种针对根病原体的保护机制。此外，我们组装了一个双通道 TRIS 装置，允许在一个腔室中同时跟踪两个根系，并实时监测 WT 和突变根基因型之间的细菌偏好性。因此，TRIS 微流控装置为复杂的根系微环境的微观微生物生态学提供了独特的见解，因此可能会加速这一重要研究领域的发现速度。
