The plant vascular system plays a central role in coordinating physiological and developmental events through delivery of both essential nutrients and long-distance signaling agents. The enucleate phloem sieve tube system of the angiosperms contains a broad spectrum of RNA species. Grafting and transcriptomics studies have indicated that several thousand mRNAs move long distances from source organs to meristematic sink tissues. Ribonucleoprotein complexes play a pivotal role as stable RNA-delivery systems for systemic translocation of cargo RNA. In this review, we assess recent progress in the characterization of phloem and plasmodesmal transport as an integrated local and systemic communication network. We discuss the roles of phloem-mobile small RNAs in epigenetic events, including meristem development and genome stability, and the delivery of mRNAs to specific tissues in response to environmental inputs. A large body of evidence now supports a model in which phloem-mobile RNAs act as critical components of gene regulatory networks involved in plant growth, defense, and crop yield at the whole-plant level.

中文翻译：

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韧皮部-移动 RNA 作为系统信号传导剂

植物维管系统通过传递必需营养素和长距离信号因子，在协调生理和发育事件方面发挥着核心作用。被子植物的去核韧皮部筛管系统包含广谱的 RNA 种类。嫁接和转录组学研究表明，数千个 mRNA 从源器官长距离移动到分生组织汇组织。核糖核蛋白复合物作为稳定的 RNA 递送系统在货物 RNA 的系统性易位中发挥着关键作用。在这篇综述中，我们评估了韧皮部和质结节运输作为一个综合的局部和系统通信网络的表征的最新进展。我们讨论韧皮部移动的小 RNA 在表观遗传事件中的作用，包括分生组织发育和基因组稳定性，以及响应环境输入将 mRNA 递送到特定组织。现在，大量证据支持一个模型，其中韧皮部移动 RNA 作为基因调控网络的关键组成部分，涉及植物生长、防御和全植物水平的作物产量。