Phloem RNA-binding proteins as potential components of the long-distance RNA transport system

Vicente Pallas,Gustavo Gómez

doi:10.3389/fpls.2013.00130

Abstract

RNA-binding proteins (RBPs) govern a myriad of different essential processes in eukaryotic cells. Recent evidence reveals that apart from playing critical roles in RNA metabolism and RNA transport, RBPs perform a key function in plant adaptation to various environmental conditions. Long-distance RNA transport occurs in land plants through the phloem, a conducting tissue that integrates the wide range of signaling pathways required to regulate plant development and response to stress processes. The macromolecules in the phloem pathway vary greatly and include defense proteins, transcription factors, chaperones acting in long-distance trafficking, and RNAs (mRNAs, siRNAs, and miRNAs). How these RNA molecules translocate through the phloem is not well understood, but recent evidence indicates the presence of translocatable RBPs in the phloem, which act as potential components of long-distance RNA transport system. This review updates our knowledge on the characteristics and functions of RBPs present in the phloem.

Highlights

RNA-binding proteins (RBPs) play a critical role in many aspects of post-transcriptional gene regulation (Glisovic et al, 2008), and perform key processes of plant development, stress response, and genome organization (Fedoroff, 2002)
This study provided the first evidence that an RNA-binding phloem protein (CmPP16) can mediate RNA transport through plasmodesmata into the phloem translocation stream by playing a relevant role in the non-cell autonomous regulation of gene expression in plants
The heterografting studies and co-IP experiments performed on phloem sap collected from pumpkin stock, cucumber scion or ungrafted cucumber plants revealed that specific phloem mRNAs are carried through the phloem translocation stream within RBP50 RNP complexes

Summary

Introduction

RNA-binding proteins (RBPs) play a critical role in many aspects of post-transcriptional gene regulation (Glisovic et al, 2008), and perform key processes of plant development, stress response, and genome organization (Fedoroff, 2002). The long-distance transport of certain host non-cell autonomously acting RNAs has been shown to be a key regulator of essential processes such as gene silencing, pathogen defense, development, stress response, and parasitic interactions (Kim et al, 2001; Yoo et al, 2004; Haywood et al, 2005; Banerjee et al, 2009; Dunoyer et al, 2010; Melnyk et al, 2011; LeBlanc et al, 2012; Kang et al, 2013).

Results

Conclusion