A Short History of Plant Light Microscopy

Abstract

When the microscope was first introduced to scientists in the 17^th century, it started a revolution. Suddenly, a whole new world, invisible to the naked eye, was opened to curious explorers. In response to this realization, Nehemiah Grew, an English plant anatomist and physiologist and one of the early microscopists, noted in 1682 "that Nothing hereof remains further to be known, is a Thought not well Calculated". Since Grew made his observations, the microscope has undergone numerous variations, developing from early compound microscopes-hollow metal tubes with a lens on each end-to the modern, sophisticated, out-of-the-box super-resolution microscopes available to researchers today. In this Overview article, I describe these developments and discuss how each new and improved variant of the microscope led to major breakthroughs in the life sciences, with a focus on the plant field. These advances start with Grew's simple and-at the time-surprising realization that plant cells are as complex as animals cells, and that the different parts of the plant body indeed qualify to be called "organs", then move on to the development of the groundbreaking "cell theory" in the mid-19^th century and the description of eu- and heterochromatin in the early 20^th century, and finish with the precise localization of individual proteins in intact, living cells that we can perform today. Indeed, Grew was right; with ever-increasing resolution, there really does not seem to be an end to what can be explored with a microscope. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC.

Keywords: GFP; cell biology; confocal microscope; light microscopy; microscopy; plant biology; science history.

Figure 1

Robert Hooke's image of ‘cells’ in a piece of cork. From (Hooke, 1665). This work is in the public domain.

Figure 2

Illustration of vine branch, cut transversely and then split halfway down the middle. From (Grew, 1682). This work is in the public domain.

Figure 3

Illustrations of M. polymorpha. From (Brisseau de Mirbel, 1835). This work is in the public domain and was obtained from ETH Zürich Library and used with permission.

Figure 4

Cell division in the algae Cladophora glomerata (shown from left to right). From (von Mohl, 1845). This work is in the public domain.

Figure 5

Microtubules of Nitella, labeled with fluorescein‐labeled sheep tubulin. (A) Treatment with the herbicide oryzalin leads to depolymerization of the microtubule network (B), followed by repolymerization (E). Scale bar = 10 µm. Reproduced with permission from (Wasteneys et al., 1993). Copyright Wiley 1993.

Figure 6

GFP expressed in maize protoplasts. Adapted from (Chiu et al., 1996) with permission. (D) Original GFP from A. Victoria, and (E) codon‐optimized variant. Copyright Elsevier 1996.

Figure 7

Fluorescent microtubules in transformed Fava bean leaf cells labeled with GFP‐MBD. Reproduced from (Marc et al., 1998) with permission. Copyright Oxford University Press 1998.

Figure 8

GFP‐TUBULIN A6–labeled Microtubules in A. thaliana petiole. (A) or cotyledon (B) cells imaged with SIM. Scale bar = 10 µm. Figure from (Komis et al., 2017). CC by license.

Figure 9

AlexaFluor488‐labeled xyloglucan in the cell wall of A. thaliana roots. Images were obtained with the ZEISS LSM780 AiryScan unit (A and B) or on a spinning disc confocal microscope (C‐E). Shown in C‐E are a single frame (C), a 100‐frame average (D) and a SRRF‐deconvolution image of the same 100 frames as in D (E).

Figure 10

STED super‐resolution image of A. thaliana chromosomal DNA, immunolabeled via REC8 (magenta). The immunolabeled (green) ZYP1 filament proteins serve to connect two sister chromatids. As both chromatids are bound by ZYP1, two distinct lines of ZYP1 protein can be seen between the two chromatids in the magnified image at the bottom. Scale bar = 0.5 µm. Figure from (Capilla‐Pérez et al., 2021). CC BY‐NC‐ND 4.0 license.