It’s generally accepted that seed germination is based on external factors such as humidity, temperature, and light. The chemical reactions caused by these stimuli affect the length of seed dormancy. But what if the seed itself decided when the time was right for germination? A study published in The Proceedings of the National Academy of Sciences (PNAS) tells us more about this possibility, implying that plants may have "brains."

The research team, composed of researchers from the School of Biosciences (University of Birmingham, United Kingdom) and the Department of Cell and Systems Biology (University of Toronto, Canada), wanted to better understand the mechanisms used by the seed to process environmental information in order to regulate and end dormancy. For their study, George Bassel and his colleagues used a genetically modified plant variety, thale cress (or Arabidopsis), in which chemical reactions can be viewed more easily. The team discovered two types of cells in the plant’s embryos that work in harmony: one encourages seed dormancy; the other fosters germination.

The researchers observed an interaction between these cells that resulted in germination at the most opportune time. The dialogue between the two cells allowed for better control over the time of germination. This intercellular “dialogue” ensured that the process was triggered neither too early nor too late. The seeds thus developed a mechanism for processing environmental information by regulating antagonistic hormones that promote dormancy (abscisic acid, ABA) and awakening (gibberellin, AG).

According to the authors: “The responses to both GA and ABA were found to occur within distinct cell types, suggesting cross-talk occurs at the level of hormone transport between these signaling centers.” What’s remarkable is that this configuration shares similarities with certain systems in the human brain. Indeed, this separation between components of the plant’s decision-making center is important because it allows for a wider range of responses to environmental stimuli. In humans, this separation contributes to more precise decision-making (for example by weakening parasitic outside signals). In plants, it helps trigger germination at just the right time.