[Allelopathy: chemical communication between plants].

Today, weed control in agricultural systems is largely based on the use of synthetic pesticides. However, the use of these compounds is increasingly controversial among farmers and consumers, who point to their harmful properties for human health and the environment. In this context, the development of eco-friendly agricultural approaches and practices is becoming essential, and allelopathy represents a promising solution. Allelopathy is the process by which plants release chemical compounds into the environment that alter the development of neighbouring plants. This process has been described since antiquity, but it was not until the 20 century that the first mechanisms were described and a definition given. Allelopathic compounds are mainly specialised metabolites belonging to three main classes: phenolic compounds, terpenoids and nitrogen containing compounds. They are generally specific to a botanical family or even a plant species. Depending on their chemical nature and the site of biosynthesis, they are released into the environment by volatilisation, leaching, exudation or degradation of plant tissues. The synthesis of these compounds is influenced by biotic and abiotic environmental factors. Allelopathic compounds can affect various plant physiological processes such as photosynthesis, mitochondrial activity, cell division and elongation, membrane transport and certain enzymatic activities. Agricultural practices such as crop rotation, intercropping and mulching already exploit the allelopathic properties of plants. Current research aims to gain a deeper understanding of the molecular and biochemical mechanisms of allelopathy by identifying the genes and metabolites involved in this process. Such knowledge improvements will allow the development of innovative and ecological agricultural approaches based on allelopathy to optimise weed management and thus reduce the use of chemical products, while preserving biodiversity within agro-ecosystems.