Destroying a gene: Increasing its related functionality?*

Hirokazu Kobayashi

CEO, Green Insight Japan, Inc.

Professor Emeritus and Visiting Professor, University of Shizuoka

Usually, when a part of the device is damaged, its functionality decreases, and when it is repaired, its functionality is restored. Genome editing, introduced in 2012, cuts specific genes at specific locations among around the 30,000 genes of individual higher animals and plants, resulting in substitutions, deletions, and insertions when repaired. This results in the loss of function of specific genes. This is called knockout (KO)-type genome editing. This cannot be distinguished from mutations that occur in nature. In other words, from a safety perspective, they are equivalent to agricultural products that have been eaten before. Using this technology, our company aims to produce decaf tea and coffee plants. The principle of this is easy to understand: it destroys the gene and stops caffeine synthesis. On the other hand, the GABA-rich tomato that was announced for sale in December 2020 uses KO-type genome editing to enhance the GABA concentration that relaxes humans. The mechanism behind this is that the enzyme that synthesizes GABA has a part that suppresses its synthesis. This enzyme becomes more active by destroying the genetic information in that part. There is also an example of a thick red sea bream produced by KO-type genome editing. In this case, the gene that prevents excessive muscle growth is missing. Individual phenomena within living organisms often have both positive and negative control systems, and if the negative one is suppressed, the positive one will act more powerfully.

Plants use sunlight to absorb carbon dioxide from the air, synthesize carbohydrates, and extract oxygen gas from water. This process is called "photosynthesis." We have discovered and patented genes that suppress this function. When one of these genes is disrupted, photosynthetic activity increases, more carbohydrates are synthesized, and plants grow even more significantly. We are currently producing such broccoli.