Confocal and electron microscopy investigations of the plant endoplasmic reticulum–nuclear envelope interface and meristematic cell divisions

The plant endoplasmic reticulum (ER) and nuclear envelope (NE) are central in the production and transport of proteins, and additionally play vital roles in cell division. However, many structural and functional aspects remain unexplored in plants. The ER is composed of tubules and cisternae, induced by Lunapark (LNP) and reticulon (RTN) proteins respectively, and has so far primarily been studied in the peripheral ER (P-ER). In this thesis, current findings are expanded by demonstrating how LNP1 and RTN6 also modulate the outer nuclear membrane tension through changing perinuclear ER (Pn-ER) structure. This influences NE integrity, nuclear pore development and transport efficiency. Using confocal and electron microscopy, this altered NE tension is established to enhance plant cell viability under osmotic stress, providing new insights into abiotic stress responses. In parallel, this thesis uncovers novel mechanisms of division within the root meristem, an area of significant agricultural relevance yet ambiguity due to its size and location. Through Serial Block-Face Scanning Electron Microscopy, root apical meristem cells are shown to experience closed mitosis with the NE remaining intact throughout division, as opposed to the typical open mitosis observed in plants where the NE breaks down during prophase. Furthermore, these closed divisions lead to the presence of cytoplasmic bridges; structures enabling organelle sharing between cells of the same lineage which suggest a unique form of intercellular communication. Notably, during the asymmetrical divisions of cortex/endoderm initial cells, the presence of three nuclei has been identified, which are observed migrating into daughter cells, pointing to another novel mechanism of closed division.

Grantor dc:publisher

Oxford Brookes University

Author dc:creator

• Field, Nadine

Contributors dc:contributor

• Kriechbaumer, Verena
• Graumann, Katja
• Pain, Charlotte

Statement dc:rights

• All rights reserved

Language dc:language

en

DOI dc:identifier

https://doi.org/10.24384/z6g2-1r63

OAI identifier oai:identifier

tle:ee958020-19dd-44b1-ae60-911509f870c1:d6bd9758-527a-46cd-bfe2-c433766e8fca:1