A good way to identify a plant is through its flowers. While there are many kinds of flowers, the flowers of each species tend to be extremely similar. So you’d expect a precise mechanism for developing the flowers. Research by Kong & colleagues suggests that it’s surprisingly chaotic.
The cells that build flowers have genes switched on or off by hormones. Kong & colleagues wanted to see how variable the cell-to-cell response to a hormone, auxin, was. They needed a method of peering inside the cells as the hormone arrived. So, they used a modified form of thale cress. This plant, also known as Arabidopsis thaliana, is the botanists’ equivalent of a lab rat. They gave the plant glowing reporters, molecules that light up with fluorescence when genes turn on, to track three auxin-responsive genes including one called DR5 under a microscope.
Kong & colleagues found that DR5 activity was ‘turned on’ by auxin, it varied wildly from one cell to the next – not because of differences in auxin levels, but due to random fluctuations inside the cells themselves. They saw this in the plant’s sepals.
Sepals are the sturdy green leaf-like organs at the base of the bud that protect the emerging flower. Even though the cells are individually “noisy” and unpredictable, the plant repeatedly produces four protective sepals in a perfect pattern.
“I really thought by the time we got to these four [sepal forming] regions, there would be a lot less randomness – but there’s not,” said lab leader, Adrienne Roeder in a press release. “Somehow, despite the noise, you still get these very clear patches where sepal organs initiate.”
The key is a process called ‘spatial averaging.’ While any individual cell may be doing its own things in response to the hormone, overall groups of cells work together to smooth out the noise. It allows the plant to use randomness when it wants to and ignore it when it doesn’t, says Roeder.
“Ultimately, the research challenges the idea that biological precision requires perfect control,” says Roeder. “Instead, it shows that nature doesn’t eliminate randomness – it builds reliable systems and processes that work despite it.”
The team aren’t just interested in what the plant does well, they also want to know how and why the process breaks down. This could be useful in processes way beyond plants like, for example, cancer, where random gene activity can drive tumor evolution.
Kong, S., Rusnak, B., Zhu, M. and Roeder, A.H.K. (2025) “Stochastic gene expression in auxin signaling in the floral meristem of Arabidopsis thaliana,” Nature Communications, 16(1), p. 4682. https://doi.org/g9k3k
Cross-posted to Bluesky & Mastodon.
The cover image shows flower buds forming from the stem cells of Arabidopsis thaliana. To show how randomly the gene DR5 is turned on, researchers used two identical copies of the gene—one glowing blue, the other yellow. In some cells, both are active (appearing white), while others show only blue or only yellow, highlighting the randomness. Still, DR5 is generally active where the hormone auxin tells it to be. All cell nuclei are marked in magenta. Image credit: Shuyao Kong.
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