Unexpected diversity among small-scale sample replicates of defined plant root compartments.

Area of Science:

• Microbiome Ecology
• Plant-Microbe Interactions
• Community Assembly

Background:

• Community assembly processes dictate species distribution and abundance in microbiomes.
• Traditional whole-root system sampling may obscure crucial intermediate assembly processes.

Purpose of the Study:

• To investigate the relative importance of community assembly processes at a finer spatial scale.
• To examine millimetre-scale sampling for observing intermediate processes in plant root microbiome assembly.

Main Methods:

• Utilized millimetre-scale sampling of the cell elongation zone in individual plant roots.
• Analyzed both rhizosphere and rhizoplane microbiomes in wheat (fibrous) and faba bean (taproot) models.
• Employed randomized null models for comparative analysis.

Main Results:

• Confirmed that plant root microbiome assembly is predominantly driven by plant selection.
• Observed significant variability between replicate millimetre-scale samples.
• Inferred the influence of priority effects or variable selection on microbiome assembly.

Conclusions:

• Finer-scale sampling (millimetre) is crucial for understanding plant root microbiome assembly.
• Priority effects during early colonization and variable selection contribute to microbiome structure.
• Plant selection remains a primary driver, but other factors add complexity at smaller scales.