Taxonomic Technology: Electrophoresis & Classification in Agricultural Botany (Part 1)

My second ever work-in-progress seminar at the University of Leeds introduced attendees to the second chapter of my PhD, which examines the use of laboratory machinery and biochemical methods to identify and analyse crop varieties at the National Institute of Agricultural Botany (NIAB) during the 1980s. By the late-twentieth century, classifying agricultural plants was a difficult task. More and more varieties were submitted to NIAB by plant breeders, while the distinguishing characteristics of varieties grew smaller and smaller. Identifying and classifying varieties had traditionally relied upon botanically-trained observers. Yet visual scrutiny of plants’ morphological characteristics was problematic, requiring both considerable expertise and grown specimens.

The problem of classifying of agricultural plants is demonstrated by these images of celery varieties. Each column here represents a distinct variety: the correct classification of these samples by eye would be a near-impossible task for the untrained observer. From G.W. Horgan, M. Talbot and J.C. Davey, ‘Plant variety colour assessment using a still video camera’, Plant Varieties and Seeds (1995) 8: 161-169.

An escape route was provided to NIAB via a form of protein fingerprinting developed in biochemistry: electrophoresis. For historians of biology, electrophoresis is best known for its use by Lewontin and Hubby to break an impasse in population genetics during the 1960s. Electrophoresis was trialed at NIAB during the same period, to little avail. Matters changed during the early years of the 1980s, when staff at NIAB’s Chemistry and Quality Assessment Branch were able to apply electrophoresis to cereal varieties. Electrophoresis works by running an electric current through a gel in which a sample sits. As different proteins carry different charges, they separate into distinct “bands” (see below).

An early image of a completed electrophoresis sample. The darker protein “bands” can be seen once the gel is chemically dyed. From R.P Ellis, ‘The identification of wheat varieties by the electrophoresis of grain proteins’, Journal of the National Institute of Agricultural Botany (1971) 12: 223-235.

Electrophoresis provided a new means of classifying agricultural plants and was promoted in NIAB’s publications as an efficient and modern technique of variety identification. The experience of the Institute during the 1980s chimes with what historians of science have termed the “molecularisation movement” in the life sciences. This movement is usually associated with genetics and the role of DNA and nucleic acids. Yet historians have called for broader studies under the theme of molecularisation, not least because of the broad use of terms such as “molecular biology” by scientists themselves. Financial gain and prestige came from NIAB’s research into electrophoresis; the technique still appears in guidelines issued by international agricultural bodies today, despite the rise of DNA sequencing. Yet electrophoresis was not the only method of classification investigated by NIAB during the 1980s, as future posts will explore…