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Decision making without a brain – The secret messengers of plants

How can these plants cope with drought and still produce corn for us to eat? CouleurPixabay 

We cannot live without plants: they provide a growing population of people with food and oxygen. But at the same time, we change the climate and thereby create harsh conditions for them to grow in. We depend on plants and with a change in climate, they start to depend on us. We need to increase our knowledge about their life, so that we help them, to help us survive on this planet.

Imagine: how would you get by in life, if you lacked a brain to think, or legs to run. When we are in danger, there is a series of steps that occur in our body to help us deal with the threat. Let’s say you are hiking in the mountains and see a bear. Your brain perceives danger and the hormone adrenaline is released. This travels through the body and causes muscles to release sugar. This gives you the energy to react and either fight or flight.

You might be surprised to hear that plants use hormones as well. But there are some differences in how plant and humans use them hormones. People have lots of different hormones in their body, all with their own specific function. Adrenaline, serotonin, and estrogen are for example all associated with a specialization, namely stress response, mood, and female reproduction, and there are many more. Plants, however, have a very small number of hormones with a big amount of functions. I study one of the few plant hormones: it is called auxin.

Auxin is involved in many aspects of plant life. For instance, it tells the plants to make flowers and helps to turn the flower into a fruit. But it is also important for the plant when it is dealing with stresses such as drought or when it is being eaten by an insect. In my research, I am investigating how one hormone can trigger so many responses, that are so different. It is almost, like there is a secret language of plants that we don’t understand yet. Once we know how the hormone makes the plants react to drought for instance, we can help improving this response.

“Because auxin is so important to plants, understanding how it works could be a key to solving the problems of facing climate crisis and world hunger.”

Scientists already have knowledge of the topic. We know auxin influences how an individual cell uses information, stored on the DNA. Every cell has the same information, like a blueprint for a building. In this example, the building would be an entire plant. A specific section of the blueprint is needed to build a root cell and another section for a cell in the flower. However, the cells need help in knowing which part of the information is important for their construction.

Imagine the hormone as a developer at a construction site. This developer tells a group of architects to read a specific part of the blueprint. The architects are called transcription factors. But the developer only sends the message when it is needed, for instance, if the soil is too dry. The architects then read the part of the plan that has the information on making a root grow. Afterwards they give orders to workers which build root cells based on the plan. This way the plant can find water in deeper layers of the soil.

Auxin (A) controls the activity of a variety of transcription factors (TF). The transcription factors are specialists, each controls a different part of the DNA, with different outcomes for the plant. Graphic by Katrin Heidemeyer.

Sometimes the plant gets a cue from the outside, such as drought, and sometimes from the inside, like the successful ripening of a flower. This results in the release of auxin, which travels through the plant, into certain cells. Then, all it does is activate transcription factors (the architects).

We understand auxin’s function, but we lack knowledge about when it is released exactly and how the effect of it can vary so much (e.g. either fruit or root is built). Because the transcription factors are so important in auxin response, we need to understand them to understand the diversity of response. Only this way, we can help to improve a specific aspect of the hormone message. I want to find out, how a transcription factor knows when to build a fruit or a root. The theory is: there are many different transcription factors, which are all experts in something.

If we go back to the construction-site, there are multiple architects present which we believe are all experts for using a specific part of the blueprint and give respective instructions to construction workers. Thus, one could be an expert in building a kitchen and one in building bedrooms. There are several different kinds of transcription factors in a plant, but we are unsure which part of the DNA blueprint they can read.

In order to understand what a transcription factor specializes in; I remove this architect from the plant. Then I watch what happens. Do construction workers still build a kitchen? And a bedroom? Or rather, are roots and fruits still built like in a normal plant? Does the plant still react the same way if it is stressed? And indeed, if one transcription factor is missing, the plant has problems making a root. If another is missing, the plant has problems making a fruit. These results show that the transcription factors are specialists.

With the information gained by this and other experiments, I hope we can better understand hormone response in plants. If we understand how auxin controls so many different processes, we might in the end be able to change the response in a specific context. We could help plants to make better decisions, when they have to face water scarcity for instance. This way, we could help plants to improve their drought resistance. By learning flora’s secret language, we can make sure the world is still a good place to live in for us and the generations to come.


Published by Katrin Heidemeyer

Katrin Heidemeyer ist Doktorandin im Bereich Biochemie an der Wageningen University and Research. Durch ihre Arbeit möchte sie das Wissen über die Spezifität von Hormon-Signalen in Pflanzen erweitern. Da ihre Interessen über Pflanzenbiologie hinausreichen, schreibt sie in ihrer Freizeit über diverse Themen. Von Ernährung zu Psychologie, der Neugierde sind keine Grenzen gesetzt.

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