Harnessing plant–microbe interactions to promote nitrogen use efficiency in cereal crops

Background: Increasing nitrogen (N) use efficiency (NUE) can enhance cereal yields, improve grain quality and reduce agrochemical inputs. However, several challenges are associated with achieving enhanced NUE, e.g., a frequently poor synchronization between N supply and demand; low grain yields per unit of N input; and inherent trade-offs between grain yield and quality. Scope: To address these challenges, we focus on the temporal perspective of NUE related processes at different growth stages, and propose the utilization of beneficial microbes, e.g. arbuscular mycorrhizal fungi (AMF) for their roles in affecting aspects of NUE particularly at the later development stages. Conclusion: Some evidence suggests that AMF can directly promote N uptake and use in cereals, by regulating N transporters, but the indirect effects of AMF on NUE related processes at different growth stages are poorly known. Here we explore AMF and their potential roles in promoting NUE related processes that enhance crop P and N uptake post-anthesis, when nutrient supply often is low. In order to fully exploit the opportunities for beneficial root-fungal symbiosis, we propose approaches for plant breeding and crop management, and consider the potential of plant-microbe interactions post-anthesis to promote NUE and the sustainable production of especially cereals.