Adapted by:
Pablo Martínez-Juarez
WriterEnvironmental economist and science journalist. For a few years, I worked as a researcher on the economics of climate change adaptation. Now I write about that and much more.
Karen Alfaro
WriterCommunications professional with a decade of experience as a copywriter, proofreader, and editor. As a travel and science journalist, I've collaborated with several print and digital outlets around the world. I'm passionate about culture, music, food, history, and innovative technologies.
About a billion years ago, an event changed the planet forever. This wasn’t the first time such an event occurred. When something similar happened millions of years earlier, it set the stage for complex life to emerge on Earth. This time, it was the plants’ turn.
It all happened because one cell engulfed another.
1+1=1. A team of researchers is attempting to recreate the conditions that gave rise to single-celled organisms in a lab. These organisms are the ancestors of all past and present plants. The project, dubbed “1+1=1,” aims to do more than study the evolution of these organisms—it could also lead to new tools for biotechnology and medicine.
The first radical change. To better understand the experiment, you have to go back to two pivotal moments in Earth’s evolutionary history. The first major event occurred about two billion years ago, though estimates vary. A simple prokaryotic cell engulfed another and converted it into an organelle.
The engulfed cell could produce energy from chemical compounds, a functional ability that the host cell turned into its power plant: the mitochondrion. This allowed the cell to evolve, generate a nucleus, and eventually lead to complex life.
Act two. History repeated itself about a billion years after the first eukaryotic cells appeared. One cell engulfed another, again turning it into an organelle. This time, the engulfed cell was a cyanobacterium, an organism capable of photosynthesis.
By merging with a eukaryotic cell, the cyanobacterium became a chloroplast, allowing its host to use photosynthesis. This development gave rise to a new kingdom of life: plants.
From symbiosis to total union. The integration between cells unfolded slowly. Initially, individual cells established a symbiotic relationship. Over the years—perhaps millions—this relationship evolved into total integration. Replicating the entire process in a lab may not be feasible, so researchers are focusing on the early stages: creating a “synthetic symbiosis” to study the steps that led to the formation of complex cells.
The team behind the project aims to observe this synthetic relationship closely under controlled conditions. They chose the bacterium Paramecium bursaria and the single-celled alga Chlorella vulgaris. These organisms naturally form a relationship in which the bacterium hosts the alga.
New tools. The team conducted the experiment using microchips designed specifically for this purpose. These chips let researchers monitor the cells closely while controlling light, temperature, and nutrient availability. To initiate the symbiosis, the team placed the bacteria under stressful conditions and examined their interactions with the other organism. The team explained the methodological details in an article published in Lab on a Chip.
More common than it seems. There are two moments in which advanced symbioses changed the course of life. However, relationships between single-celled organisms that result in endosymbiosis don’t appear to be rare. Scientists have recently discovered similar cases in nature, such as the algae Braarudosphaera bigelowii absorbing a newly identified cyanobacterium called UCYN-A.
Image | Picturepest | Ren Ran (Unsplash)
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