Plant plasmodesmata bridges form through ER-dependent incomplete cytokinesis

Area of Science:

• Plant Cell Biology
• Plant Development
• Cellular Communication

Background:

• Plant cells divide incompletely, forming plasmodesmata for intercellular communication, crucial for multicellularity.
• The molecular mechanisms stabilizing plasmodesmata during cell division are not fully understood.

Purpose of the Study:

• To elucidate the molecular events governing the stabilization of plasmodesmata during plant cell division.
• To understand how incomplete cell division facilitates intercellular communication in plants.

Main Methods:

• Utilized electron tomography to visualize the transition from cell plate fenestrae to plasmodesmata.
• Investigated the role of the endoplasmic reticulum (ER) and ER-plasma membrane (PM) tethers in plasmodesmata formation.
• Conducted genetic deletion experiments in *Arabidopsis*.

Main Results:

• Observed endoplasmic reticulum (ER) connecting daughter cells across fenestrae, guiding plasma membrane (PM) molding.
• Demonstrated that ER presence prevents fenestrae fusion, leading to plasmodesmata formation, while its absence causes closure.
• Identified ER-PM protein tethers (MCTP3, MCTP4, MCTP6) as critical for stabilizing nascent plasmodesmata.
• Showed that genetic deletion of these tethers in *Arabidopsis* reduces plasmodesmata formation.

Conclusions:

• The endoplasmic reticulum plays a pivotal role in incomplete plant cell division by guiding plasmodesmata formation.
• ER-PM tethers are essential for stabilizing plasmodesmata during the cell plate maturation process.
• These findings reveal a novel mechanism for promoting intercellular communication in plants through regulated cell division.