Chapter 10
Utilizing Potato Virus X to Monitor RNA Movement
Zhiming Yu, Sung Ki Cho, Pengcheng Zhang, Yiguo Hong,
and David J. Hannapel
Abstract
Mobility assays coupled with RNA profiling have revealed the presence of hundreds of full-length non-cellautonomous messenger RNAs that move through the whole plant via the phloem cell system. Monitoring
the movement of these RNA signals can be difficult and time consuming. Here we describe a simple, virusbased system for surveying RNA movement by replacing specific sequences within the viral RNA genome of
potato virus X (PVX) that are critical for movement with other sequences that facilitate movement. PVX is a
RNA virus dependent on three small proteins that facilitate cell-to-cell transport and a coat protein
(CP) required for long-distance spread of PVX. Deletion of the CP blocks movement, whereas replacing
the CP with phloem-mobile RNA sequences reinstates mobility. Two experimental models validating this
assay system are discussed. One involves the movement of the flowering locus T RNA that regulates floral
induction and the second involves movement of StBEL5, a long-distance RNA signal that regulates tuber
formation in potato.
Key words Potato virus X, RNA mobility assay, FT, BEL5
1 Introduction
Plants have evolved a unique long-distance signaling system that
utilizes cell-to-cell plasmodesmatal connections and a specialized
phloem cell network. In addition to its function in the transport of
sugars from source to sink organs, the phloem is an important
conduit for moving signals that mediate responses to stress and
processes of development [1]. Phloem sap profiling has now confirmed that the phloem functions in a dynamic process to deliver
signals that respond to internal and environmental cues. Numerous
full-length mRNAs have been identified in the sieve element system
of several plant species [2–6]. Using heterografts and movement
assays, several mRNAs have been identified that are transported
through the vascular system. It is now clear that RNA trafficking
plays an important role in systemic signaling that controls plant
development and defense [7]. Using a heterograft system between
Manfred Heinlein (ed.), RNA Tagging: Methods and Protocols, Methods in Molecular Biology, vol. 2166,
https://doi.org/10.1007/978-1-0716-0712-1_10, © Springer Science+Business Media, LLC, part of Springer Nature 2020
181
Utilizing Potato Virus X to Monitor RNA Movement
Zhiming Yu, Sung Ki Cho, Pengcheng Zhang, Yiguo Hong,
and David J. Hannapel
Abstract
Mobility assays coupled with RNA profiling have revealed the presence of hundreds of full-length non-cellautonomous messenger RNAs that move through the whole plant via the phloem cell system. Monitoring
the movement of these RNA signals can be difficult and time consuming. Here we describe a simple, virusbased system for surveying RNA movement by replacing specific sequences within the viral RNA genome of
potato virus X (PVX) that are critical for movement with other sequences that facilitate movement. PVX is a
RNA virus dependent on three small proteins that facilitate cell-to-cell transport and a coat protein
(CP) required for long-distance spread of PVX. Deletion of the CP blocks movement, whereas replacing
the CP with phloem-mobile RNA sequences reinstates mobility. Two experimental models validating this
assay system are discussed. One involves the movement of the flowering locus T RNA that regulates floral
induction and the second involves movement of StBEL5, a long-distance RNA signal that regulates tuber
formation in potato.
Key words Potato virus X, RNA mobility assay, FT, BEL5
1 Introduction
Plants have evolved a unique long-distance signaling system that
utilizes cell-to-cell plasmodesmatal connections and a specialized
phloem cell network. In addition to its function in the transport of
sugars from source to sink organs, the phloem is an important
conduit for moving signals that mediate responses to stress and
processes of development [1]. Phloem sap profiling has now confirmed that the phloem functions in a dynamic process to deliver
signals that respond to internal and environmental cues. Numerous
full-length mRNAs have been identified in the sieve element system
of several plant species [2–6]. Using heterografts and movement
assays, several mRNAs have been identified that are transported
through the vascular system. It is now clear that RNA trafficking
plays an important role in systemic signaling that controls plant
development and defense [7]. Using a heterograft system between
Manfred Heinlein (ed.), RNA Tagging: Methods and Protocols, Methods in Molecular Biology, vol. 2166,
https://doi.org/10.1007/978-1-0716-0712-1_10, © Springer Science+Business Media, LLC, part of Springer Nature 2020
181