Getting to the root of weeds and wheat Scientists have started to realise that plants interact with each other at the level of the root system. Now, they are studying whether weeds inhibit the growth of wheat plants through root signalling. Climate Change and Environment © Thinkstock Wheat (Triticum aestivum) is a major European crop, which may be being encroached upon by the blackgrass weed (Alopercurus myosuroides). Many recent studies have found that roots of different plant species influence each other; however, the mechanisms of this interaction remain unclear.The EU-funded project 'Molecular basis for root-root interactions between wheat and weed' (INTERACTROOT) project set out to discover how blackgrass and wheat interact at the root level. The project also looked into any specific compounds (called exudates) that blackgrass may use to signal wheat roots.Project members first developed a system for growing plants that would allow the roots to be studied. This involved growing plants in clear, sterile boxes and a transparent growing medium under controlled growth conditions (nutrients, light, temperature, etc.).Growing wheat and blackgrass together reduced the number and length of lateral roots in wheat plants; when wheat plants were grown together, the length, but not the number, of lateral roots was reduced. Nutrient supply had no effect on these interactions.A model system was used to understand the action of the blackgrass root exudate better. This system showed that blackgrass root exudates increased the concentration of calcium (a common signalling molecule) in plant root cells.This direct evidence that the blackgrass weed influences the growth of wheat roots has long-reaching implications for agricultural productivity. An important next step is to identify the specific exudates responsible for these changes. Keywords Wheat, blackgrass, exudate, plants, root–root interaction
