Emergence of tolerance and avoidance strategies from local and systemic responses to nitrogen: insights from modelling of auxin-mediated root plasticity

A recent study exploring the role of auxin in root plasticity sheds light on how plants optimize nutrient uptake and resist stress. Auxin, a plant hormone, governs various root growth processes, including responses to nitrogen (N) levels. To investigate the impact of local and systemic auxin responses on N uptake and utilization, researchers employed functional-structural-plant (FSP) modeling.

By incorporating a simplified auxin module into an existing FSP model, the study aimed to simulate physiological adaptations in roots based on N availability.

The simulations demonstrated that local auxin responses improved N uptake by encouraging root development in deeper soil layers, thereby increasing the plant's N forage and avoiding nitrogen stress. Conversely, systemic auxin responses led to root growth near the soil surface, reducing plant size and N demand, which enhanced stress tolerance.

However, this systemic strategy resulted in a trade-off with local auxin responses, as both mechanisms compete for biomass and N investment driven by source-sink dynamics within the plant.

The findings highlight the importance of considering both tolerance and avoidance strategies when assessing plant responses to nutrient availability. By representing hormone-mediated root plasticity within an FSP model, scientists can gain valuable insights into the complex mechanisms plants employ to capture resources efficiently.

These insights are particularly relevant for developing suitable crop genotypes for medium to low-input agricultural systems, where understanding root phenotypic plasticity can lead to more sustainable farming practices.