Plants seem to take up exogenous RNA that was artificially designed to target specific genes, followed by activation of the RNA interference (RNAi) machinery. It is, however, not known whether plants use RNAs themselves as signalling molecules in plant-to-plant communication, other than evidence that an exchange of small RNAs occurs between parasitic plants and their hosts. Exogenous RNAs from the environment, if taken up by some living organisms, can indeed induce RNAi. This phenomenon has been observed in nematodes and insects, and host Arabidopsis cells secrete exosome-like extracellular vesicles to deliver plant small RNAs into Botrytis cinerea. Here we show that micro-RNAs (miRNAs) produced by plants act as signalling molecules affecting gene expression in other, nearby plants. Exogenous miRNAs, such as miR156 and miR399, trigger RNAi via a mechanism requiring both AGO1 and RDR6. This emphasizes that the production of secondary small interfering RNAs is required. This evidence highlights the existence of a mechanism in which miRNAs represent signalling molecules that enable communication between plants.

植物似乎吸收了人工设计用于靶向特定基因的外源 RNA，随后激活了 RNA 干扰 (RNAi) 机制。然而，除了有证据表明寄生植物与其宿主之间发生小 RNA 交换外，植物是否使用 RNA 本身作为植物间通讯的信号分子尚不清楚。来自环境的外源性 RNA，如果被一些生物体吸收，确实可以诱导 RNAi。这种现象已在线虫和昆虫中观察到，宿主拟南芥细胞分泌外泌体样细胞外囊泡，将植物小 RNA 输送到灰葡萄孢中. 在这里，我们表明植物产生的微小 RNA (miRNA) 作为信号分子影响附近其他植物的基因表达。外源性 miRNA，例如miR156和miR399，通过需要 AGO1 和 RDR6 的机制触发 RNAi。这强调需要产生二级小干扰 RNA。这一证据强调了一种机制的存在，在该机制中，miRNA 代表能够实现植物间通信的信号分子。