The controversial world of genetically modified (GM) crops has a parallel in nature, where similar processes occur spontaneously. The phenomenon has long baffled scientists, but a recent study offers a glimpse into solving this enigma, potentially reshaping our perspective on evolution and GM crops.
The traditional “tree of life” concept, representing the evolutionary relationships among organisms, suggests that more closely related species are positioned closer together on the tree. However, this model oversimplifies reality. In some groups of organisms, interconnections between branches are common, blurring the notion of a hierarchical tree of life. Bacteria, in particular, exhibit a web-like pattern of evolution, a result of the movement of genetic information between branches.
Horizontal gene transfer, also known as lateral gene transfer, is the process whereby genetic material, including genes, is exchanged between organisms outside of the conventional parent-to-offspring route. It enables the sharing of genetic information across distant branches of the evolutionary tree, and plays a pivotal role in the rapid dissemination of advantageous traits, such as antibiotic resistance among bacteria.
Initially presumed to be confined to microbes, horizontal gene transfer has been observed in a wide array of plants, animals, and fungi. This process can transmit genetic blueprints for advantageous traits, contributing to evolution.
Horizontal gene transfer is particularly fascinating in grasses, a group of plants that encompasses essential crops like rice, wheat, and maize. Grasses cover nearly 40% of the Earth’s landmass and constitute a significant portion of human caloric intake. Evidence of horizontal gene transfer among grass species, in both wild and cultivated varieties, is apparent through alterations in their genomes. Yet, the precise mechanism and frequency of these transfers have remained elusive.
A recent study, published in New Phytologist, delves into this enigma by examining Alloteropsis semialata, a tropical grass. The research aims to estimate the frequency of gene transfers into this species, explore their impact on plant evolution, and ascertain the pace at which they occur.
The study involved sequencing multiple genomes of Alloteropsis semialata to trace the evolutionary history of each gene, identify foreign genes, and determine when and how they were transferred. The research revealed that genes were consistently acquired throughout the species’ evolutionary journey, with a foreign gene being incorporated approximately every 35,000 years. This, however, underestimates the actual transfer rate, as it doesn’t account for transient genes that may have been lost.
Genes that offer recipients an evolutionary advantage, such as disease resistance, stress tolerance, and increased energy production, are more likely to be retained. These genes may have undergone millions of years of refinement in the donor species, allowing recipients to bypass this lengthy optimization process.
The study also raises intriguing parallels between natural horizontal gene transfer and genetic modification (GM) technology. Both processes lead to the integration of foreign genes into an organism’s genome. Horizontal gene transfer could be occurring through mechanisms similar to those used in GM crop creation, potentially through a process called “reproductive contamination.”
Further research will explore the possibility of recreating natural gene transfers observed in the study. If successful, this could prompt a reevaluation of how we perceive GM crops, suggesting they might be more akin to natural processes than previously believed.