Dynamics of the Pollen Sequestrome Defined by Subcellular Coupled Omics

Area of Science:

• Plant reproductive biology
• Molecular biology
• Genomics and proteomics

Background:

• Angiosperm reproduction success hinges on efficient pollen tube growth for fertilization.
• Pollen grains accumulate stored messenger RNAs (mRNAs) for later protein synthesis during tube growth.
• Understanding mRNA storage and translation regulation is key to plant fertility.

Purpose of the Study:

• To investigate the dynamics of stored and translated transcripts in tobacco pollen.
• To characterize the composition and function of different subcellular mRNA-protein complexes.
• To define and analyze the "pollen sequestrome" and its role in translational control.

Main Methods:

• Transcriptomic and proteomic analyses were conducted on tobacco pollen.
• Subcellular compartments including EDTA/puromycin-resistant particles, polysomes, and free ribonuclear particles were isolated.
• Analysis spanned pollen development and in vitro pollen tube growth.

Main Results:

• The composition of mRNA-containing complexes is dynamic, with transcript redistribution during pollen development.
• A novel compartment, the "pollen sequestrome," was defined as a dynamic storage site for translationally repressed transcripts.
• EDTA/puromycin-resistant particles were identified as key mediators of mRNA sequestration, likely representing aggregated monosomes.

Conclusions:

• The pollen sequestrome is a highly dynamic regulatory compartment essential for pollen development and function.
• Dynamic transcript redistribution among complexes is a significant mechanism for translational regulation in pollen.
• The sequestration of mRNAs in specific complexes optimizes rapid and localized protein synthesis in growing pollen tubes.