# PHR‐Mediated Pi Starvation Response Mobile Messenger RNAs Represent Noncoding Transcripts in Recipient Tissues

## TL;DR

The study shows that certain mRNAs travel long distances in plants under phosphate starvation and function without being translated into proteins in recipient tissues.

## Contribution

The paper identifies PHR-mediated PSR-specific mobile mRNAs as noncoding transcripts in recipient tissues.

## Key findings

- Hundreds of PSR-specific mobile mRNAs are transported long-distance in Arabidopsis.
- PHR function is essential for the mobility of PSR-specific mRNAs.
- PSR-specific mobile mRNAs are not translated in recipient tissues but are in donor tissues.

## Abstract

Nutritional deficiency for phosphate (Pi) or nitrogen triggers long‐distance transport of specific mobile mRNAs, but little is known about the underlying regulation, function, and structural features of these mobile nutrient starvation‐specific mRNAs. Here, heterografting and high‐throughput sequencing are used to explore the landscape of long‐distance mRNA transport in Arabidopsis under normal and Pi‐starvation conditions. Hundreds of Pi starvation response (PSR)–specific mobile mRNAs are discovered, although their abundance is constant between normal and Pi starvation conditions. The mobility of these PSR‐specific mobile mRNAs is largely dependent on PHOSPHATE STARVATION RESPONSE (PHR) function, based on mutant analysis. Notably, translatome analysis and transgenic experiments reveal that these PHR‐mediated PSR‐specific mobile mRNAs are translated in donor tissues, but not in recipient tissues. Further, these mobile mRNAs harbored a more unfolded 5′ UTR than nonmobile mRNAs, non‐PSR‐mobile mRNAs, and nitrogen starvation–response mobile mRNAs. The study reveals that these PSR‐specific mobile mRNAs are transported to recipient tissues to carry out a function independently of their encoded protein.

Mobile messenger RNAs (mRNAs) can travel long distances, serving as systemic signals that participate in plant growth and stress acclimation. This work determines that PHR proteins mediate the Pi starvation response (PSR)‐specific long‐distance transport of mRNAs and that these PSR‐specific mobile mRNAs represent noncoding transcripts in recipient tissues.