Genomes are not static.
They change over time. Spontaneously. Unexpectedly.
That is the mechanism of evolution, isn’t it? Genetic change is necessary for organisms to improve and adapt to environmental conditions, that do change too. Because evolution needs variation, it feeds with novelty. Just as much to create a new genetic function at the same pace the environment demands it.
And that is exactly what Nature has been doing on our crops for thousands of years; driving genetic change.
We don’t tend to question this genetic tuning because it is orchestrated by Nature. It is natural. And natural is safe, because it seems untouched, unmodified.
But nothing further from reality; modification and change lie at the very foundation of Nature.
Nature is a Genetic Engineer
Did you know that Nature is an incredibly sophisticated genetic engineer, and has at hand the most creative tools to drive genetic change?
And some of the changes that Nature has written in the genome of our crops during evolution are actually pretty big. Sometimes they even involve the acquisition of new specialized genetic functions through the cloning and doubling of entire existing genes. Gene duplication science calls it.
Whether a duplicate gene is then retained by the plant or silently lost depends on its function, and on how valuable it is to the organism. This awesome mechanism that allows a gene to get copied-and-pasted several times within a genome was key to plant evolution. Without gene duplication, the plasticity of a plant in adapting to changing environments would be severely limited.
A very peculiar and ancestral strategy for the duplication of genes in a genome, particularly abundant among plants, is the so-called retrotransposition.
Yes, I know, science likes tongue twisters.
Retrotransposition is a natural genetic mechanism that involves the copy-paste of entire stretches of DNA, the transposable elements. These DNA stretches, also called jumping genes, are often former viruses which integrated into their host’s genome, and duplicated or modified some host genes in the process.
This viral mistake came in handy, helping evolution to work on additional functions for the new genes — a sort of genetic recycling.
There are many examples of this genetic modification but a very juicy one is found in grapes. It seems that the ancestor seed of grapes was black-skinned in origin. The random insertion of a retrotransposon nearby the gene producing black pigment turned it off giving rise to white grapes. The subsequent random loss of that same retrotransposon generated an additional red-skinned grape variety, and gifted us with the delicious tannin-rich red wine.
Red grape varieties are the result of an ancient natural genetic modification of grape seeds
Transposable elements are widespread and comfortably living in the genome of many organisms, including ourselves.
In order to allow them to stay, evolution has engineered ways to silence their ability to move. These genetic intruders are thus not infectious anymore, and plants — and ourselves, can enjoy the benefits of their ancient insertion.
But evolution did not give rise to white or red grapes just for us to enjoy different flavors of wine.
It was a matter of chance, that random retrotransposition of some DNA stretches happened nearby skin pigment genes. And a matter of luck, that our ancestors transformed those genetic changes in the pigment into something palatable more than 10,000 years ago.
Now scientists try to use those genetic tricks of Nature in order to advance wine and viticulture research.
And well, why not, also to explore new grape varieties, that evolution did not craft.
Let’s raise our wine glasses to that.