Below ground, where roots silently make their way through the earth, a surprisingly complex and clever process takes place. Plants appear to use a kind of internal clean-up system to keep their roots not only clean, but smart. This process - called autophagy - allows plants to grow better, absorb more water and nutrition, and recover faster after difficult weather conditions. A new study from the University of Copenhagen, published May 18, 2025, shows how important this system is, especially for the formation of lateral roots.
The scientists examined a well-known model plant: Arabidopsis thaliana, also called sand rocket. They discovered that the plant receives a signal every few hours to form new lateral roots. Those lateral roots are essential because they allow the plant to access water and nutrients deeper in the soil. The signal comes from a growth hormone called auxin, and an associated protein, ARF7, that helps carry out that message.
But just as a light bulb doesn't keep blinking unless you turn it on and off again and again, the signal to form roots must also be restarted each time. That's where autophagy comes in. This is the process by which the plant neatly clears out obsolete or redundant proteins so that the growth signal can be given again. The protein NBR1 plays an important role in this process: it "tags" ARF7 to be broken down in special parts of the cell, the vacuoles. Thus, the plant makes way for a new cycle of root growth.
What happens when this clearance system doesn't work? The researchers turned off autophagy in some plants, and the result was clear. These plants retained too much of the protein ARF7, so the growth gene no longer came at the right times. The roots formed sloppily or not at all. The plants absorbed less water and did not grow as well. Under the microscope, the researchers saw vacuoles full of waste and debris - a sign that the system had stalled.
Why is this important for agriculture? Because plants with a functioning autophagy process get more powerful roots. Not only can they withstand drought or flooding better, but they also need less fertilizer and water. That's good for farmers as well as the environment. Less fertilizer means less pollution of rivers and oceans, and less water use is crucial in dry areas.
And the benefits go further. Stronger roots can help make food crops - such as rice, wheat or cassava - more resilient at a time when the weather is becoming increasingly erratic. In Denmark, experimental fields are already being tested with crops where the autophagy system has been optimized, for example using soil bacteria that stimulate this process. Those plants recover faster after a dry period and ultimately yield more.
What makes this research so special is that autophagy is not an unknown, complicated trick. It is a basic process present in almost all floral plants. That means we don't have to start from scratch: we can use something that nature itself has already figured out, and improve it in clever ways.
The next step for the researchers is to see if other proteins in the plant are also recycled in the same way, and how factors such as light or temperature affect this process. They will also investigate how autophagy has evolved in evolution, for example in mosses or other simple plants.
What is clear: Those who understand the roots of plants also understand how we can strengthen agriculture. And by re-examining an ancient clearance system, researchers have now found a key to more sustainable, resilient food production.
