Structure vs. chemistry: Alternate mechanisms for controlling leaf microbiomes

Area of Science:

• Microbiology
• Plant Science
• Ecology

Background:

• Traditional phyllosphere microbiome analysis uses DNA from whole leaves.
• Investigating distinct microbial communities on upper (adaxial) and lower (abaxial) leaf surfaces is crucial for understanding plant-microbe interactions.

Purpose of the Study:

• To compare microbial communities on the adaxial and abaxial leaf surfaces of Rhapis excelsa and Cordyline fruticosa.
• To determine if microbial diversity varies with time (day/night) and location.
• To explore the factors influencing differential microbial colonization on leaf surfaces.

Main Methods:

• Swab collection from adaxial and abaxial leaf surfaces of two plant species.
• Sampling at different times (noon, midnight) and locations.
• Co-occurrence network analysis to study microbial community structure.

Main Results:

• The abaxial leaf surface consistently showed fewer bacteria compared to the adaxial surface.
• Bacteria were predominantly found on the adaxial surface, while fungi were limited to the abaxial surface.
• Differences in leaf surface microstructure and chemical activity, along with higher stomatal density on the abaxial surface, may influence microbial distribution.

Conclusions:

• The adaxial and abaxial leaf surfaces harbor distinct phyllosphere microbiomes.
• Plant defense mechanisms, including chemical and mechanical strategies, likely shape microbial communities, particularly on the abaxial surface.
• Reduced microbial diversity on the abaxial surface is a result of plant-microbe interactions and specialized leaf surface properties.