背景回顾：Plants are constantly adapting to ambient fluctuations through spatial and temporal transcriptional responses. 

主要研究：Here, we implemented the latest-generation RNA imaging system and combined it with microfluidics to visualize transcriptional regulation in living Arabidopsis plants. This enabled quantitative measurements of the transcriptional activity of single loci in single cells, in real time and under changing environmental conditions. 

结果1-磷酸盐响应基因：Using phosphate-responsive genes as a model, we found that active genes displayed high transcription initiation rates (one initiation event every ~3 s) and frequently clustered together in endoreplicated cells. 

结果2-单个细胞基因表达异质性：We observed gene bursting and large allelic differences in single cells, revealing that at steady state, intrinsic noise dominated extrinsic variations. 

结果3-转录抑制：Moreover, we established that transcriptional repression triggered in roots by phosphate, a crucial macronutrient limiting plant development, occurred with unexpectedly fast kinetics (on the order of minutes) and striking heterogeneity between neighbouring cells.

结论：Access to single-cell RNA polymerase II dynamics in live plants will benefit future studies of signalling processes.

 摘 要 

植物通过时空转录响应，一直在适应周边环境的波动。本文中，作者应用最新一代的RNA成像系统，将其与微流体技术相结合，来可视化拟南芥活株中的转录调控。这使得作者能够实时地在不断变化的环境条件下，定量测量单个细胞中单个基因座的转录活性。以磷酸盐响应基因为模型，作者发现激活基因表现出较高的转录起始率（大概每3s一次起始事件），并且经常在核内复制的细胞中发生聚集。作者在单个细胞中观察到了基因的爆发和巨大的等位基因差异，说明了在稳定状态下，内在噪音主导了外在变异。此外，作者还发现，作者限制植物发育的关键大量营养素，磷酸在植物根中引发的转录抑制响应时间以分钟为单位，并且相邻细胞之间的存在显著的异质性。在活体植物中获得单细胞层面上的RNA聚合酶II动态将有助于未来对于植物信号传导的研究。