Natural Genetic Engineering
How Garden Bacteria made the first Genetically Modified Foods
Genetic Engineering is a human-invented technique, right? Wrong. A simple garden bacteria, Agrobacteria first came up with the idea to make genetically modified foods.
Genetic Engineering is a subject of great debate, and is often portrayed as a human-contrived strategy to alter nature. However, the fact is that it was taking place in nature, for the same reasons that humans use it long before it was discovered by us in a simple backyard rose bush.
Genetically Modified (GM) foods are a subject of great contention, and are often seen as human tampering which, admittedly, they are. What is often unknown is that humans didn't invent genetic modification, nor were we the first to apply it to our food supply, we borrowed the idea from a common soil bacteria that also uses genetic engineering to 'tamper' with its food.
Agrobacterium tumefaciens is a bacterium found in just about all soils, and is the cause of crown gall disease on just bout all dicotyledonous plants, but most notably roses. The bacteria live quite happily in the soil, feeding on whatever nutrients they can absorb from their surroundings. That is, until they get a whiff of an injured plant, which they can detect from chemicals leached by damaged plant cells. They follow the breadcrumb trail, or rather the phenol trail, all the way to the damaged plant cell. Once there, they glue themselves to the host, with their extracellular matrix: a gelatinous mix of sugar-proteins. They then pierce the cell with a syringe-like pilus. They use this pilus to inject the plant with genes, which they have cut out of their own genome.
These genes, collectively called transfer DNA, or T-DNA, are sent into the plant cell, coated by proteins that function to navigate to the nucleus, the command centre of the cell. When they get there, the genes are spliced into the plant cell, making a GMO. And remember, this GMO has been created without any human interaction. The T-DNA contains slightly different genes from one bacterial strain to another, but they always serve the same functions.
Firstly, they encode instructions for the plant to manufacture certain amino acids that are the favoured food of the bacteria. These amino acids, called opines, are never naturally produced by the plant, nor are they easily utilized by other organisms. The Agrobacteria, however, are specifically adapted to eat them, and in having the plant manufacture them, the bacteria have created themselves a cozy niche, free from competition.
Secondly, the bacteria send genes that instruct for hormone production, causing the affected cell to multiply rapidly, and indeterminately, very much like cancer. These virulence (vir) genes essentially multiply the effect of the bacteria’s efforts, so that an entire mass of food-supplying GM plant cells can be cultivated. The result is that tumorous growths occur on the affected plants, which we recognize in our garden as galls.
When humans discovered this amazing phenomenon, we soon put it to use, for precisely the purpose for which it was originally invented by bacteria: namely, to make better and more abundant food for ourselves. Today, this method of genetic engineering is used to enrich vitamins, and reduce allergens in our food, as well as to make crops that require less water and fewer pesticides.
