Peace talks: symbiotic signaling molecules in arbuscular mycorrhizas and their potential application

Since the Green Revolution, intensive application of agrochemicals has increased productivity in agriculture, at a great cost in terms of water pollution, loss of soil fertility and biodiversity, and negative effects on human health. Scientific advance and increasing public awareness are driving a change toward sustainable practices. In such a context, the symbiosis between plants and arbuscular mycorrhizal (AM) fungi is extremely promising: AM interaction improves plant mineral nutrition and stress tolerance. In turn, AM fungi receive plant photosynthesis-derived carbon. A complex chemical dialogue mediates plant-fungus recognition and symbiosis establishment: AM fungi perceive root-secreted strigolactones, which promote spore germination, hyphal growth, branching and metabolism. Host roots recognize their symbionts through chitin-derived molecules. Such Myc–factors activate a range of symbiotic responses, preparing the plant to a successful association. Here we review the most recent advances in knowledge of AM signaling molecules, with a focus on their possible application.