Elevated O₃ concentrations alter the compartment-specific microbial communities inhabiting rust-infected poplars

Area of Science:

• Plant pathology
• Environmental science
• Microbiome research

Background:

• Elevated ozone (O3) impacts plant susceptibility to pathogens like rust.
• The role of plant-associated microbiomes in O3-pathogen interactions is not well understood.

Purpose of the Study:

• To investigate how ozone exposure and differential sensitivity affect poplar response to Melampsora larici-populina rust.
• To determine the role of microbiomes in four plant compartments (phyllosphere, rhizosphere, root endosphere, bulk soil) in this interaction.

Main Methods:

• Poplar clones with varying ozone sensitivity were exposed to ambient air with or without elevated ozone (40 or 60 ppb).
• Plants were inoculated with Melampsora larici-populina urediniospores.
• Microbiome diversity, composition, and network complexity were analyzed across four plant compartments.

Main Results:

• Higher ozone sensitivity in poplars correlated with significantly lower rust severity.
• Ozone's impact on microbial community diversity and composition was compartment-specific and differed between poplar clones.
• Microbial network complexity patterns were opposite between the two poplar clones.
• Fungal communities in the phyllosphere and root endosphere showed reciprocal derivation, suggesting transmission.

Conclusions:

• Plant ozone sensitivity influences rust pathogen susceptibility, modulated by distinct microbiome responses.
• Ozone stress alters plant microbiomes in a compartment-dependent manner, with potential above- and below-ground microbial exchange.
• Understanding these complex interactions is crucial for predicting plant performance under combined environmental stresses.