PHR-Mediated Pi Starvation Response Mobile Messenger RNAs Represent Noncoding Transcripts in Recipient Tissues.

Area of Science:

• Plant molecular biology
• Nutrient signaling
• Gene expression regulation

Background:

• Nutrient deficiency, particularly phosphate (Pi) or nitrogen, induces long-distance mRNA transport.
• The regulation, function, and structural characteristics of these mobile nutrient starvation-specific mRNAs remain largely uncharacterized.

Purpose of the Study:

• To investigate the landscape of long-distance mRNA transport in Arabidopsis under normal and Pi-starvation conditions.
• To identify and characterize Pi starvation response (PSR)-specific mobile mRNAs.

Main Methods:

• Arabidopsis heterografting and high-throughput sequencing were employed.
• Mutant analysis, translatome analysis, and transgenic experiments were conducted.
• Structural analysis of mRNA 5' untranslated regions (UTRs) was performed.

Main Results:

• Hundreds of PSR-specific mobile mRNAs were identified, with constant abundance under normal and Pi-starvation conditions.
• The mobility of these PSR-specific mobile mRNAs is PHOSPHATE STARVATION RESPONSE (PHR) function-dependent.
• These mobile mRNAs are translated in donor tissues but not recipient tissues and possess a more unfolded 5' UTR compared to non-mobile or nitrogen starvation-responsive mRNAs.

Conclusions:

• PSR-specific mobile mRNAs are transported to recipient tissues to perform a function independent of their encoded protein.
• PHR pathway plays a crucial role in the mobility of these PSR-specific mobile mRNAs.
• Structural features, such as unfolded 5' UTRs, may facilitate the transport and function of these mobile mRNAs.