Mint fragrance inhibits the growth of weeds

17-Apr-2020 - Germany

In the competition for land, nutrients, and water, some plants are very successful: They impede the growth of their competitors by chemical signals that trigger cell death in the neighboring plant. Scientists at the Botanical Institute of the Karlsruhe Institute of Technology (KIT) are investigating how this effect comes about in order to use it for the development of environmentally friendly bioherbicides.

Hobby gardeners and forest walkers are familiar with the phenomenon that other plants do not thrive in the vicinity of a walnut tree and that wild garlic and mint displace their neighbours. Experts call this chemical warfare allelopathy. "In most cases, these are not poisons but chemical signals that cause the effect in the target plant," explains Peter Nick, Professor of Molecular Cell Biology at the KIT Botanical Institute. While wild garlic and mint themselves are immune to the effect of their chemical signals, biological communication triggers self-regulated cell death in the neighbouring plant. In this mechanism of plant communication, the scientists see a way to develop novel and environmentally friendly bioherbicides whose effect is specific to a particular weed species without affecting the crop plants.

"We walked through nature with an open mind and asked ourselves whether there might be a connection between the strong growth of mint and its distinctive scent, which is different for each mint variety," says Nick. Based on the extensive mint collection at the KIT Botanical Institute, essential oils of different mints were extracted, individual bioactive components were provided with molecular markers and their signalling effect on other plants was investigated. Cell cultures showed that the compound menthone, which is present in the essential oil of mint, activates a process in competing plants by which microtubili - finely branched, tubular protein structures - destroy themselves. "It has been shown that menthone is particularly effective against dock, a weed found on mountain pastures," says Dr. Mohammed Sarheed. The biologist has published the results of his research at the KIT Botanical Institute as a doctoral thesis on "Allelopathic compounds from Mint target the cytoskeleton from cell biology towards application as bioherbicides". In his thesis, he also describes that the scent oil of horse mint targets the protein actin, where it leads to cellular suicide and is thus highly effective against field bindweed. Here, the researchers understand the mechanism, although they have not yet identified the causative substance. Sarheed's investigations at KIT also showed that menthon inhibits the growth of HeLa cells - human cancer cells. "This makes its use as a cancer drug conceivable," said the scientist whose research was funded by scholarships of the Iraqi Ministry of Education and Science as well as the Karlsruhe House of Young Scientists at the KIT.

Weeds are one of the main reasons for crop losses; they compete with crops for the same ecological niche. "If they were not controlled, 30 to 50 percent of agricultural yield would be lost," says Nick. "Conventional herbicides are an ecological burden and weeds soon become resistant. They only work for a limited time," says the biologist. The development of environmentally friendly weed control agents is therefore a global challenge for food security. The aim is to find strategies to control agricultural ecosystems in harmony with evolution. The Swiss Research Institute of Organic Agriculture (FiBL) and the Max Planck Institute for Chemical Ecology in Jena are among the institutions involved in the KIT Botanical Institute's research on mint allelopathy.

Note: This article has been translated using a computer system without human intervention. LUMITOS offers these automatic translations to present a wider range of current news. Since this article has been translated with automatic translation, it is possible that it contains errors in vocabulary, syntax or grammar. The original article in German can be found here.