The role of RTNLB3 in endoplasmic reticulum structure and cytokinesis in planta

Reticulons are a large family of ER membrane shaping proteins that are ubiquitous to eukaryotic cells. Plants possess the highest number of different reticulon proteins, which contain a conserved reticulon homology domain that has been associated with their ER curvature inducing properties. Individual reticulon family members are suspected to play other roles in cell function, although most remain unknown. RTNLB3 is a reticulon that has been identified in a plasmodesmatal proteomic screen and could play a role in constricting the ER membrane into the highly curved rod of the desmotubule, forming the core of these structures within plant cell walls. The role of the ER in cytokinesis and the importance of the regulation of ER structure during this process has not been previously investigated in detail. This study demonstrates that RTNLB3 becomes highly concentrated at the cell plate during its formation and that over-expression of a non-functional truncated form of the protein interferes with cell wall formation. Over-expression of truncated RTNLB3 results in an increased proportion of cisternal ER within the ER network. Stable over-expression of the construct proved lethal to BY-2 cell lines and Arabidopsis thaliana plants. Analysis of meristematic root tip cells of Arabidopsis plants stably transformed with an inducible truncated RTNLB3 construct, and subsequent induction prior to analysis, resulted in disruption to cell plate formation. RTNLB3 therefore may play a direct role in the formation of the cell plate; the loss of regulation of ER membrane curvature within the network prevents successful completion of cytokinesis; or a combination of these factors. The lethal phenotypes observed within this study, and the abnormal ultrastructure of cells identified as a result of over-expression of a mutant form of RTNLB3, demonstrate the importance of this ER shaping protein and ER structure in the process of plant cytokinesis.

Grantor dc:publisher

Oxford Brookes University

Year dc:date

2017

Author dc:creator

• Kiviniemi, Petra Marianne

Contributors dc:contributor

• Hawes, Chris
• Osterrieder, Anne

Statement dc:rights

• All rights reserved

Language dc:language

en

DOI dc:identifier

https://doi.org/10.24384/hhds-3c05

OAI identifier oai:identifier

tle:fae37ea6-877e-45b4-95f4-7c1ddcd7ece6:d6bd9758-527a-46cd-bfe2-c433766e8fca:1