CLEM, a universal tool for analyzing structural organization in thylakoid membranes.

Abstract

Chlorophyll (Chl) plays a crucial role in photosynthesis, functioning as a photosensitizer. As an integral component of this process, energy absorbed by this pigment is partly emitted as red fluorescence. This signal can be readily imaged by fluorescence microscopy and provides a visualization of photosynthetic activity. However, due to limited resolution, signals cannot be assigned to specific subcellular/organellar membrane structures. By correlating fluorescence micrographs with transmission electron microscopy, researchers can identify sub-cellular compartments and membranes, enabling the monitoring of Chl distribution within thylakoid membrane substructures in cyanobacteria, algae, and higher plant single cells. Here, we describe a simple and effective protocol for correlative light-electron microscopy (CLEM) based on the autofluorescence of Chl and demonstrate its application to selected photosynthetic model organisms. Our findings illustrate the potential of this technique to identify areas of high Chl concentration and photochemical activity, such as grana regions in vascular plants, by mapping stacked thylakoids.

Plant phenotyping relevance

葉緑素自家蛍光と電子顕微鏡を相関させるCLEMプロトコルを開発・適用し、チラコイド構造内の葉緑素分布と光化学活性を可視化する手法が中心であるため。

Code and data availability

The article describes a CLEM workflow (fluorescence microscopy + TEM of thylakoid membranes) but provides no public repository, dataset, image deposit, or author analysis code. The data availability statement points only to the article's supplementary material (figures) and to the corresponding author upon request, so

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