A pectin acetyl‐transferase facilitates secondary plasmodesmata formation and RNA silencing movement between plant cells
OPEN ACCESS
Author / Producer
Date
2025-05
Publication Type
Journal Article
ETH Bibliography
yes
Citations
Altmetric
OPEN ACCESS
Data
Rights / License
Abstract
Some silencing small (s)RNAs, comprising micro (mi)RNAs and small-interfering (si)RNAs, move between plant cells to orchestrate gene expression and defense. Besides possible redundancy or embryo lethality, a prevalent challenge in genetic studies of mobile silencing is to discriminate bona fide alterations to sRNA movement from impaired cell-autonomous sRNA activity within silencing-recipient cells. Without such clarifications, cell-to-cell mobility factors are yet to be unequivocally identified. Consequently, known properties of sRNA movement, including contextuality and directionality, remain poorly explained. Circumstantial evidence and synthetic biology pinpoint plasmodesmata (PDs) – the pores traversing plant cell walls (CWs) – as the likely channels involved. Yet, how plants control the number of primary and secondary PDs developing respectively before and after CW formation remains largely unknown. Here, we address these intertwined issues in Arabidopsis using a forward screen for compromised epidermis-to-mesophyll movement of an artificial (a)miRNA. We identify a pectin acetyl-transferase mutation that, we demonstrate, reduces amiRNA physical trafficking but also impedes siRNA, GFP, and viral movement by decreasing the frequency of leaf secondary PDs. sRNA movement at leaf interfaces involving primary PDs remains unaffected, however, as does miRNA and GFP cell-to-cell mobility in roots, hinting at how movement's contextuality and directionality might be achieved. We also show that reducing de-esterified pectin depolymerization decreases leaves' symplasmic connectivity, whereas defective pectin biogenesis increases PD number. Combining genetics with antibody-based pectin probing and atomic force microscopy helps delineate a mechanistically coherent framework whereby pectin esterification and/or abundance impact CW loosening, a process required for CW extension during which secondary PDs form to enable macromolecular trafficking.
Permanent link
Publication status
published
External links
Editor
Book title
Journal / series
Volume
122 (3)
Pages / Article No.
Publisher
Wiley
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
RNA silencing; movement; plasmodesmata; pectin; cell wall
Organisational unit
03876 - Voinnet, Olivier / Voinnet, Olivier
Notes
Funding
153468 - SNF_310030_153468 (SNF)
197832 - Genome-scale, functional and mechanistic investigation of plant microRNA cell-to-cell and vascular movement (SNF)
197832 - Genome-scale, functional and mechanistic investigation of plant microRNA cell-to-cell and vascular movement (SNF)