Wild plants can edit their genomes the same way we create GM crops – and it could be key to evolution


Sheffield, October 10 (The Conversation) Genetically modified (GM) crops may be controversial, but similar processes occur naturally with wild plants. However, scientists have long been puzzled about how these processes occur. Our recent study may help researchers solve the mystery.

People often use the “tree of life” as a metaphor to describe the evolutionary relationships between organisms. The more closely related the species are, the closer they appear in the tree.

However this is a bit misleading, as the reality is more complex.

Species are not always isolated from other branches on their own evolutionary path. In fact, in some groups of organisms, the relationships between branches are so common that we may need to abandon the concept of the tree of life altogether.

This is especially true for bacteria, where evolutionary relationships look more like a tangled web than a tree. Crosstalk between branches occurs due to the movement of genetic information.

Horizontal gene transfer (also known as lateral gene transfer) is the process by which DNA fragments (such as genes) move between organisms outside the common parent-to-offspring pathway. This allows genetic information to be shared between distant branches of the tree of life without sexual reproduction, and is responsible for the rapid spread of traits such as antibiotic resistance among bacteria.

Originally scientists thought this phenomenon was limited to microorganisms, but we now know it also occurs in a wide range of plants, animals, and fungi, where it can spread the genetic recipe for traits that have evolutionary advantages. .

Horizontal gene transfer in grasses Grasses are one of the most important groups of plants and include crops such as rice, wheat, and maize. They cover about 40 percent of the Earth’s landmass and make up the majority of human calorie intake.

Horizontal gene transfer between grass species has been found in wild and cultivated species alike. While we know that these transfers occur through marks left in the species’ genome (the complete set of DNA instructions in a cell), we still don’t know the mechanism behind it. Nor do we know how often this happens – our recent study published in New Phytologist aims to address this.

Understanding the speed of horizontal gene transfer will allow us to assess its impact on the planet and plant evolution and how quickly it can help plants adapt to changes. For example, is it so common that plants may already be using it in response to climate change? We sequenced multiple genomes for the tropical grass Alloteropsis semiolata to estimate the frequency of gene transfer in this species. Our study traced the evolutionary history of each gene in the genome, identified genes that were of foreign origin, and determined when and where they were transferred.

Our findings show that genes were acquired continuously throughout the evolutionary history of this species, with the introduction of a foreign gene approximately every 35,000 years.

However, this is a dramatically underestimate of the actual rate of transfer within the species because it does not show gene transfer that may have subsequently been lost. Most transferred genes are unlikely to provide any benefit to the recipient – ​​and may even have negative consequences for the plant if they disrupt essential parts of the recipient’s genetic code. Genes that provide no benefit to the recipient are often lost. This type of transient gene is very difficult for scientists to detect.

The genes that are retained are generally those that provide an evolutionary advantage to the recipient. For example, many of the horizontally transferred genes found in grasses confer increased disease resistance, stress tolerance, and energy production. These genes may have adapted to the genome of the donor species over millions of years. Horizontal gene transfer allows the recipient to skip this lengthy purification process.

GM technology Ultimately horizontal gene transfer and GM crops have the same result: a gene of foreign origin is inserted into the genome of the recipient.

Our study provided information about how often horizontal transfers are occurring. But we still don’t know how genes are moving between distantly related species. There are many theories but we think a mechanism called reproductive contamination is the most likely. This mirrors some of the methods used to create GM crops.

There are several different methods by which you can create a GM plant – some requiring intensive human intervention and some not. Simple techniques such as repeated pollination or pollen tube passage-mediated transfer require minimal human intervention. In these methods, small pieces of DNA from a third person travel into the same pollen tube established by the father to contaminate the embryo in the seed. In principle this could occur naturally.

In the future we plan to test this idea and see if we can recreate some of the natural transfers we documented. If successful, it may be time to rethink how we view GM crops. Perhaps they are closer to natural processes than we think. (talk) GRS GRS


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