How Plants Are Named

Part 2

by Mary Francis, Fairfax Master Gardener Intern
In the 20th century, plant names began changing very rapidly due to the convergence of three extraordinary advances in science. These revolutionary findings have far reaching implications in taxonomy, now and even more so in the future. Their impact cannot be underestimated in myriad disciplines beyond taxonomy.

In a 1936 paper, Alan Turing described what he called an “automatic machine” that could solve any computing problem described as a sequence of mathematical steps. He also showed that one machine could stimulate another machine and that a machine could hold both data and code. In 1938 Turing worked with the British government where he famously cracked the codes used by the Germans in World War II by deciphering their “Enigma” machine. Thus began the computer age.

In 1953, James Watson and Francis Crick published a stunning one-page article in the journal “Nature”. They described the structure of deoxyribonucleic acid (DNA) as a three-dimensional double stranded helix (a spiral chain), a twisted-ladder structure. with four nucleotides (also called nucleic acids). The nucleotides link together (polymerize) always in pairs to form the building blocks of DNA. Watson and Crick recognized that DNA contains the genetic code of living things.

In 1983, Kary B. Mullis formulated a revolutionary way to make copies of DNA molecules. The polymerase chain reaction (PCR) enabled the replication of portions of DNA in large quantities in a laboratory.

James Watson, Francis Crick and Kary Mullis were each rewarded the Nobel Prize. The work of Alan Turing remained classified long after World War II. Since the Nobel Prize is not awarded posthumously, Turing did not receive a Nobel Prize for his discoveries.

Testing methods to sequence DNA began as slow, painstaking, manual techniques. The same was true for PCR tests. Now, PCR and DNA sequencing are automated tests with results often available in hours once the purified nuclear material is produced. These tests have moved far beyond the university and research settings from which they began.

Computer advances are simply astonishing. Our cell phones have more computing power than the computers used to send Apollo 11 to the moon. Artificial intelligence is a reality.

With relatively easy to perform tests and the aid of advanced computers, scientists can rapidly and reliably elucidate the genetic information of plants and analyze the data in a sophisticated manner. Now, unprecedented knowledge of the relationships of plants to one another on a genetic level forces a reorganization of the classification and naming of plants. Scientists are more able to determine relationships on an evolutionary scale by studying the similarities and divergences in the DNA of plants.

The genetic material of plasmids is often analyzed. At their most basic level, plasmids are small circular pieces of DNA that replicate independently from the host’s chromosomal DNA. Scientists worldwide are rapidly building large databases of plant DNA, both from plasmids and from the cell nucleus.

The nomenclature and classification of plants will continue to confound gardeners and scientists for years to come. The potential changes brought about by our new knowledge are just beginning. For scientists, this is an adventure at least on par with the profound change in understanding living things following the acceptance of the theory of evolution.

References
• Molecular Structure of Nucleic Acids, a Structure for Deoxyribose Nucleic Acid, James D. Watson,
   Francis H.C. Crick, Nature, April 1953
• The Francis Crick Papers, U.S. National Library of Medicine Profiles in Science
• Turing’s Enduring Importance, Simson Garfinkel, Massachusetts Institute of Technology (MIT) Technology
   Review, 2012
• The Discovery of PCR, Deana Namuth-Covert, University of Nebraska Lincoln
• Chemical Components of PCR, Deana Namuth-Covert, University of Nebraska Lincoln