Weed-induced crop allelopathy : deciphering molecular underground interactions

Today, agriculture faces many challenges, including meeting growing demand for food production and reducing arable land. Among them, weeds cause on average 34% yield loss because their presence negatively impacts crop growth by competing for nutrients, space, light and water. To manage weeds, synthetic herbicides are used but represent several dangers for the environment and for human health. In addition, they are implicated in the development of pesticide-resistant weeds. As there is a growing societal demand for greener agriculture, alternative solutions are being explored. Allelopathy, which refers to the inhibition of the growth of one plant by another due to the production of allelochemicals, is a promising approach for weed control. Although the synthesis of allelochemicals by the crop has a metabolic cost, it represents an efficient way to reduce weeds’ growth and germination. In certain cases, allelopathy can even be triggered by the detection of weeds by the crop plant. Nevertheless, the non-self-recognition, underground chemical dialogue and metabolic pathways involved in induced allelopathy are not fully understood. The aim of the present work is to identify the signal molecules from weeds that triggers an allelopathic response in a crop plant. First, model plants will be selected based on literature. Culture systems will be established to allow the study of their allelopathic relationship. The crop plant and weed will be cultivated alone or in co-culture, first under hydroponic conditions and, in a second phase, in rhizoboxes to shift towards more realistic edaphic conditions. Weed’s root exudates will be sampled, fractionated and the bioactive compounds that induce a surge in the production of allelochemicals by crop plant will be identified. In parallel, a transcriptomic analysis will be conducted. Ultimately, a better understanding of plant-plant chemical communication will improve the effectiveness of sustainable weed control.