Root Form and Function for Improving NUE for Sustainable Agriculture: A Focus on Nitrate

Nitrate, the predominant nitrogen form in aerobic soils, is the most limiting nutrient for plant growth and productivity. The N fertilizers application has achieved large increase in yields, although, its large use is associated with an increase of groundwater pollution due to leaching N losses. Even though, best crop management can contribute to minimize nitrate pollution ensuring high crop yield, plant improvement for nitrate use efficiency (NUE), especially at low nitrate availability, could be considered a challenge for the development of sustainable agriculture. NUE is considered to be a complex trait including N uptake efficiency (NUpE) and N utilization efficiency (NUtE) components, whereby understanding the mechanisms that regulate these processes become crucial for improving NUE in crops. In particular, NUpE component, defined the plant ability to take up N from the soil, is tightly correlated to root form and function relationship in plants. In our laboratory, research has been focused on understanding this relationship in terms of morphology and architecture (form) and nitrate acquisition (function) of the root system aimed to improve NUpE component. The results indicated that higher order lateral roots and greater tip numbers enhancing the ability to absorb nitrate making plant competitive to limiting nitrate. A better understanding of root trait genetic control will provide an important tool to improve NUE by assisted breeding.