Genotypic variation and nitrogen stress effects on root anatomy in maize are node specific

Area of Science:

• Agricultural Science
• Plant Biology
• Crop Physiology

Background:

• Root phenotypes are crucial for improving nitrogen acquisition in crops.
• Root anatomy influences resource capture, metabolic costs, hydraulic conductance, anchorage, and soil penetration.
• Current cereal root phenotyping often overlooks the well-developed nodal root system, where critical nitrogen uptake occurs.

Purpose of the Study:

• To investigate root anatomical variations across nodes in field-grown maize (Zea mays L.) under varying nitrogen conditions.
• To identify root anatomical traits associated with high nitrogen use efficiency (NUE).
• To understand the plasticity of root anatomy in response to nitrogen stress.

Main Methods:

• Examined root anatomy across multiple nodes in maize hybrids and inbred lines.
• Compared root phenotypes under high and low nitrogen regimes.
• Analyzed relationships between anatomical features (e.g., root diameter, cortical aerenchyma, metaxylem area) and shoot biomass.

Main Results:

• Genotypes with high NUE showed larger root diameter and less cortical aerenchyma under nitrogen stress compared to low NUE genotypes.
• Root anatomical phenotypes, including cortex, stele, and metaxylem areas, scaled with root diameter.
• Root anatomical traits varied significantly across nodes, with early nodes not being representative of later ones.

Conclusions:

• Nitrogen use efficiency in maize is linked to specific root anatomical traits, such as increased root diameter and reduced cortical aerenchyma under stress.
• Root anatomy exhibits significant nodal variation and plasticity in response to nitrogen availability.
• Targeting nodal root anatomy can lead to the development of maize varieties better adapted to low nitrogen environments.