Root Exudates: A Means of Communication and Interaction between Plants
Photo: Gabriela Brändle,
Agroscope
Plants release root exudates – compounds that influence the growth of their neighbours – into the soil. Understanding this mechanism allows us to devise new approaches for biological weed control.
Plant roots are capable of adapting to cope with changing environmental conditions. In particular, they can release compounds into the soil that influence the growth of neighbouring plants. Understanding these mechanisms and incorporating them into biological weed control in the field constitutes a promising approach to reducing the use of inputs, in particular herbicides, and minimising tillage.
Interactions between plants in the soil are still largely a mystery. A team of scientists at Agroscope have now explored these interactions as part of a study on buckwheat.
A closer look at buckwheat root exudates
The team examined how buckwheat perceived its neighbours through its roots, as well as the composition of the root exudates it releases into the soil. They also aimed to determine whether the composition of these exudates is specific to the tested species or is a general response to the presence of neighbouring plants, and to evaluate the effects of buckwheat root exudates on the roots of a weed – viz., redroot pigweed.
To do this, the scientists developed an innovative system for collecting root exudates: an ultra-high-performance liquid chromatography analysis method coupled with high-resolution mass spectrometry as well as a biological test enabling the application of root exudates to redroot pigweed.
Direct connection between exudates and weed control
The study revealed that the composition of buckwheat root exudates varied in the presence of a neighbouring plant such as redroot pigweed or another buckwheat plant. In direct competition, i.e. when plants grow next to one another, changes in the root growth of buckwheat and redroot pigweed were observed and characterised. Moreover, even in the absence of direct competition, by applying root exudates of a buckwheat plant from a crop of buckwheat alone or buckwheat that had grown in the presence of redroot pigweed, it was shown that the root growth of redroot pigweed was affected only by the exudates of buckwheat that had grown in the presence of redroot pigweed, and not by the exudates of buckwheat that had grown alone. This suggests that the effect of buckwheat exudates on redroot pigweed was induced by redroot pigweed and that changes in the composition of buckwheat root exudates contributed to the changes in root architecture observed in redroot pigweed.
By establishing a direct link between physical presence, chemical signals and morphological responses, these findings highlight the importance of exudates in biological weed control. They help us understand how plants modify the composition of their root exudates in the presence of neighbouring plants, and how they affect each other’s root systems in this way.
Future research could focus on identifying the compounds in these exudates that are responsible for suppressing weed root growth, thereby facilitating the development of new control strategies.
Conclusions
- Plant roots release compounds into the soil that influence the growth of neighbouring plants.
- The study revealed that in buckwheat, the composition of the root exudates varies in the presence of different neighbouring plants, causing changes in the root growth of the interacting plants.
- These results highlight the importance of exudates in biological weed control. Future research could focus on identifying the compounds responsible for suppressing root growth in weeds.
Bibliographical reference
Neighbour‑induced changes in root exudation patterns of buckwheat results in altered root architecture of redroot pigweed.