Stay home or go beyond: deciphering the mechanisms underlying ARGONAUTE1 loading and sRNA movement in plants

Small RNAs (sRNA) are essential regulators of gene expression, controlling development and preserving genome integrity, all across eukaryotic organisms.

To execute their final functions, sRNA are loaded into an ARGONAUTE (AGO) protein to guide through sequence complementarity the regulation of target genes.

In plants, sRNAs are divided into small interfering RNA (siRNA) and microRNA (miRNA), and both can be loaded into AGO1 for cell-autonomous action, or move out of the cell to act non-cell autonomously.

This proposal outlines a series of complementary experiments to mechanistically study the loading of sRNA into AGO1 and to understand how it contributes to the intra- and inter-cellular movement of sRNA in plants.

By combining cell biology, RNA biochemistry, deep-sequencing analysis, nuclear fractionation methods, micrografting and super-resolution microscopy, this project aims at: i) characterize the nuclear and cytoplasmic sRNA loading complexes (LCs), ii) decipher the connection between sRNA biogenesis and LCs and, iii) determine how sRNA loading could affect the sRNA movement.

The results obtained will advance the state of the art in plants in our understanding of AGO1 loading mechanism, the execution of the AGO1 function and sRNA movement.

Studying these pathways goes beyond mere mechanistic knowledge, as sRNA movement is being exploited to modulate plant and pathogen gene expression towards improving crop productivity and enhancing stress/pathogen tolerance, a booming strategy known as Spray-induced gene silencing.

Altogether, this project is expected to create a wealth of original information, providing a meaningful contribution to European excellence and competitiveness in the field.