Nitrogen remobilization during leaf senescence: lessons from Arabidopsis to crops

As a result of climate changes, land use and agriculture have to adapt to new demands. Agriculture is responsible for a large part of the greenhouse gas (GHG) emissions that have to be urgently reduced in order to protect the environment. At the same time, agriculture has to cope with the challenges of sustainably feeding a growing world population. Reducing the use of the ammonia-nitrate fertilizers that are responsible for a large part of the GHGs released and that have a negative impact on carbon balance is one of the objectives of precision agriculture. One way to reduce N fertilizers without dramatically affecting grain yields is to improve the nitrogen recycling and remobilization performances of plants. Mechanisms involved in nitrogen recycling, such as autophagy, are essential for nutrient remobilization at the whole-plant level and for seed quality. Studies on leaf senescence and nutrient recycling provide new perspectives for improvement. The aim of this review is to give an overview of the mechanisms involved in nitrogen recycling and remobilization during leaf senescence and to present the different approaches undertaken to improve nitrogen remobilization efficiency using both model plants and crop species.