Luxembourg National Research Fund

The hidden part of plants – the root systems – play a vital role both in plant survival, and in our ecosystem, as plants store carbon in the soil. Scientists are working to understand how roots are affected by changes in water availability, but how do researchers even approach the study of roots?

Understanding how roots grow to deal with varying resource availability is an important question plant biologists are looking to answer – especially in times of climate change and extreme weather events. One of them is Samuele Ceolin, a plant biologist at the Luxembourg Institute of Science and Technology (LIST), who studies root dynamics to find out how dynamically roots grow so they can get the most out of changes in the availability of water in the soil.

Previous research in natural environments has evaluated the root growth dynamics occurring in the long term – seasons or years – leading to a better understanding of the carbon cycles in different environments.

“Other studies determined how plastic roots are in adapting to limitations of water and nutrients. Such findings contributed to improving the management of irrigation and fertilisation and in plant breeding for the selection of plant strains able to perform well in conditions of water scarcity”, Samuele explains, adding that researchers have also looked at roots on the molecular level to untangle the molecular mechanisms involved in root growth.

Understanding how roots adapt to sudden changes

“One of the main challenges remaining in root science is to understand how dynamically roots adapt when exposed to quick changes in water availability around them, for example after a summer thunderstorm . Roots can adapt to changes in moisture availability occurring over the course of the seasons: but how do roots react whenever these changes occur within days or even hours?”

Root systems are considered the hidden half, making it no easy feat to monitor root growth through time. Despite the availability of techniques to overcome the issue, Samuele explains the sampling process can be difficult, time consuming, prone to errors and expensive.

“On top of this, manipulating the soil moisture locally along a soil profile and the delineation of the water uptake patterns represent an additional challenge.”

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Recreating nature in the lab

As part of his PhD, Samuele carried out experiments on maize plants where he was able to manipulate – in space and time – the amount of water available to the plant.

“By applying water pulses in different parts of the soil in contact with the roots and in different moments in time, I could monitor if and how the roots adapted their growth according to daily changes in water availability.

“This was possible thanks to a MRI technology (at Forschungszentrum Jülich) allowing me to obtain images of the root systems, repeatedly and without destroying them, every 48 hours. These experiments gave me the possibility to shed light on the unknown of the short time scale dynamics.”

While plant biologist Samuele is still in the process of finalising the data analysis from his experiments, the results so far look promising, seemingly indicating that roots do adapt fast and dynamically whenever the conditions in soil moisture quickly vary along the soil profile. These results could contribute to establishing root dynamic responses in improved plant breeding programmes and vegetation modelling.