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Life is based on signals. Any molecule or process can become a signal, when it transmits information. As laid down by Karl Bühler in his Organon Theory (1934), information depens on the context between sender and recipient. This creates specificity. The same molecule or event can convey different "meanings", when the context changes. Evolution was shaped by communication between cells and organisms being improved, sometimes also hijacked. While our conventional understanding of communication is dominated by signals that are generated by movements (we call that behaviour), most signals are of chemical natures (even in animals, Homo sapiens included). When we succeed to identify and manipulate signals, we gain control about other organisms, and this in a manner that is specific and avoids collateral damage. In other words: When we understand those signals, we can design strategies to steer our agricultural ecosystems in harmony with evolution. We might not get 100% control over the system, but maybe only 90%. However, this 90%-compromise will be more sustainable than our current technological approach, where we basically go for differential poisoning of our ecosystems.

We need plant protection, but our herbicides challenge the environment, poison the groundwater, and cause collateral damage to harmless or even beneficial organisms. We need more specificity. This is possible - all living beings use numerous signals to influence others for their own sake. Can we use this? That is what we did: Mints are very competitive and smell quite differently, depending on the species. We found that these scents are signals, by which they persuade other plants into suicide. For Horsemint we have investigated this in detail and developed on the base of this knowledge an application, by which we can suppress Bindweed, a pertinent problem in organic cereal production.

Publication:

195. Sarheed M, Schärer HJ, Wang-Müller QY, Flury P, Maes C, Genva M, Fauconnier ML, Nick P (2023) Signal, not poison – Horsemint essential oil for weed control. Agriculture 13, 712 - pdf

"Weeds" are often crop wild relatives that thrive in the human-made, artificial environment, while not "paying back" (so-called cultural parasitism). The use two tricks: "Weeds" shed their seeds or fruits, before they can be used by humans, and they germinate at individual and diverse time points (so-called dormancy), such that they are no good for standardised agriculture. However, all our crops were, once upon a time, also "weeds", for instance, oat, rye, or barley. By breeding, humans have "educated" them to stop shedding their seeds or germinate just when they want. The genetic difference between "weed" and "crop" is tiny. Before we try to eliminate "weeds", we should rather learn from evolution and search for more sustainable compromises.

Weedy Red Rice is one of these cultural parasites that meanwhile causes around 30% of global yield loss. Despite its impact, it has remained enigmatic. Using our collection of Weedy Red Rice from all over the world, especially from Northern Italy, where the team of Aldo Ferrero has systematically collected, we could show with genetic markers that Weedy Red Rice evolved from domesticated rice. Hereby, the genes inactivated during domestication were reinstalled by a few specific mutations. Since rice is no longer transplanted, but sown by machines, there is no way to recognise and eliminate the weedy plants during an early stage. Thus, our technical agriculture has made us humans create our own "weeds".

Publications

156. Grimm A, Sahi VP, Amann M, Vidotto F, Fogliatto S, Devos KM, Ferrero A, Nick P (2020) Italian Weedy Rice – A Case of De-Domestication? Ecology and Evolution 10, 8449-8464 - pdf

100. Grimm A, Fogliatto S, Nick P, Ferrero A, Vidotto F (2013) Microsatellite markers reveal multiple origins for Italian Weedy Rice. Ecol Evolution 3, 4786-4798 - pdf