Locating the microbes along the maize root system under nitrogen limitation: a root phenotypic approach

Area of Science:

• Agricultural Science
• Microbiology
• Plant Science

Background:

• Low nitrogen (LN) uptake efficiency in crops presents significant environmental and economic challenges.
• Root adaptive phenotypes and microbial synergies offer a potential strategy to enhance plant nitrogen acquisition.
• Understanding the spatial distribution of root-associated prokaryotes under LN conditions is crucial but underexplored.

Purpose of the Study:

• To characterize the spatial distribution of maize root prokaryotes under low nitrogen (LN) conditions.
• To investigate correlations between prokaryotic genus abundance and root architectural/anatomical phenotypes.
• To identify potential synergies between root traits and microbes for improved nitrogen cycling in agriculture.

Main Methods:

• Studied 4-week-old maize plants grown in 30 L mesocosms under LN conditions with two sandy soil mixtures.
• Collected root, rhizosphere, and bulk soil samples from various depths, root classes (lateral/axial), and root types (seminal/crown).
• Performed 16S rRNA gene metabarcoding on extracted DNA and analyzed plant growth responses.

Main Results:

• Sampling location was a significant factor influencing root prokaryotic diversity, explaining ~5% of the variance.
• Distinct microbial communities were observed in seminal roots, shallow crown roots, and deep crown roots.
• Lateral root branching density (LRBD) explained 10% of the variance in rhizosphere and root tissue, with 37 genera correlating significantly with architectural phenotypes.

Conclusions:

• Root sampling location and architectural traits are critical factors associated with microbial nitrogen cycling.
• Synergies between root traits and nitrogen-cycling microbes hold promise for enhancing agricultural sustainability.
• This research provides insights into optimizing plant-microbe interactions for improved nitrogen use efficiency.